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/-
Copyright (c) 2022 Chris Birkbeck. All rights reserved.
Released under Apache 2.0 license as described in the file LICENSE.
Authors: Chris Birkbeck
-/
import Mathlib.Algebra.Group.Subgroup.Pointwise
import Mathlib.Data.ZMod.Basic
import Mathlib.GroupTheory.GroupAction.ConjAct
import Mathlib.LinearAlgebra.Matrix.SpecialLinearGroup
#align_import number_theory.modular_forms.congruence_subgroups from "leanprover-community/mathlib"@"ae690b0c236e488a0043f6faa8ce3546e7f2f9c5"
/-!
# Congruence subgroups
This defines congruence subgroups of `SL(2, ℤ)` such as `Γ(N)`, `Γ₀(N)` and `Γ₁(N)` for `N` a
natural number.
It also contains basic results about congruence subgroups.
-/
local notation "SL(" n ", " R ")" => Matrix.SpecialLinearGroup (Fin n) R
attribute [-instance] Matrix.SpecialLinearGroup.instCoeFun
local notation:1024 "↑ₘ" A:1024 => ((A : SL(2, ℤ)) : Matrix (Fin 2) (Fin 2) ℤ)
open Matrix.SpecialLinearGroup Matrix
variable (N : ℕ)
local notation "SLMOD(" N ")" =>
@Matrix.SpecialLinearGroup.map (Fin 2) _ _ _ _ _ _ (Int.castRingHom (ZMod N))
set_option linter.uppercaseLean3 false
@[simp]
theorem SL_reduction_mod_hom_val (N : ℕ) (γ : SL(2, ℤ)) :
∀ i j : Fin 2, (SLMOD(N) γ : Matrix (Fin 2) (Fin 2) (ZMod N)) i j = ((↑ₘγ i j : ℤ) : ZMod N) :=
fun _ _ => rfl
#align SL_reduction_mod_hom_val SL_reduction_mod_hom_val
/-- The full level `N` congruence subgroup of `SL(2, ℤ)` of matrices that reduce to the identity
modulo `N`. -/
def Gamma (N : ℕ) : Subgroup SL(2, ℤ) :=
SLMOD(N).ker
#align Gamma Gamma
theorem Gamma_mem' (N : ℕ) (γ : SL(2, ℤ)) : γ ∈ Gamma N ↔ SLMOD(N) γ = 1 :=
Iff.rfl
#align Gamma_mem' Gamma_mem'
@[simp]
theorem Gamma_mem (N : ℕ) (γ : SL(2, ℤ)) : γ ∈ Gamma N ↔ ((↑ₘγ 0 0 : ℤ) : ZMod N) = 1 ∧
((↑ₘγ 0 1 : ℤ) : ZMod N) = 0 ∧ ((↑ₘγ 1 0 : ℤ) : ZMod N) = 0 ∧ ((↑ₘγ 1 1 : ℤ) : ZMod N) = 1 := by
rw [Gamma_mem']
constructor
· intro h
simp [← SL_reduction_mod_hom_val N γ, h]
· intro h
ext i j
rw [SL_reduction_mod_hom_val N γ]
fin_cases i <;> fin_cases j <;> simp only [h]
exacts [h.1, h.2.1, h.2.2.1, h.2.2.2]
#align Gamma_mem Gamma_mem
theorem Gamma_normal (N : ℕ) : Subgroup.Normal (Gamma N) :=
SLMOD(N).normal_ker
#align Gamma_normal Gamma_normal
| Mathlib/NumberTheory/ModularForms/CongruenceSubgroups.lean | 73 | 75 | theorem Gamma_one_top : Gamma 1 = ⊤ := by |
ext
simp [eq_iff_true_of_subsingleton]
|
/-
Copyright (c) 2018 Kenny Lau. All rights reserved.
Released under Apache 2.0 license as described in the file LICENSE.
Authors: Kenny Lau, Mario Carneiro, Johan Commelin, Amelia Livingston, Anne Baanen
-/
import Mathlib.RingTheory.Localization.FractionRing
import Mathlib.RingTheory.Localization.Ideal
import Mathlib.RingTheory.Noetherian
#align_import ring_theory.localization.submodule from "leanprover-community/mathlib"@"1ebb20602a8caef435ce47f6373e1aa40851a177"
/-!
# Submodules in localizations of commutative rings
## Implementation notes
See `RingTheory/Localization/Basic.lean` for a design overview.
## Tags
localization, ring localization, commutative ring localization, characteristic predicate,
commutative ring, field of fractions
-/
variable {R : Type*} [CommRing R] (M : Submonoid R) (S : Type*) [CommRing S]
variable [Algebra R S] {P : Type*} [CommRing P]
namespace IsLocalization
-- This was previously a `hasCoe` instance, but if `S = R` then this will loop.
-- It could be a `hasCoeT` instance, but we keep it explicit here to avoid slowing down
-- the rest of the library.
/-- Map from ideals of `R` to submodules of `S` induced by `f`. -/
def coeSubmodule (I : Ideal R) : Submodule R S :=
Submodule.map (Algebra.linearMap R S) I
#align is_localization.coe_submodule IsLocalization.coeSubmodule
theorem mem_coeSubmodule (I : Ideal R) {x : S} :
x ∈ coeSubmodule S I ↔ ∃ y : R, y ∈ I ∧ algebraMap R S y = x :=
Iff.rfl
#align is_localization.mem_coe_submodule IsLocalization.mem_coeSubmodule
theorem coeSubmodule_mono {I J : Ideal R} (h : I ≤ J) : coeSubmodule S I ≤ coeSubmodule S J :=
Submodule.map_mono h
#align is_localization.coe_submodule_mono IsLocalization.coeSubmodule_mono
@[simp]
theorem coeSubmodule_bot : coeSubmodule S (⊥ : Ideal R) = ⊥ := by
rw [coeSubmodule, Submodule.map_bot]
#align is_localization.coe_submodule_bot IsLocalization.coeSubmodule_bot
@[simp]
theorem coeSubmodule_top : coeSubmodule S (⊤ : Ideal R) = 1 := by
rw [coeSubmodule, Submodule.map_top, Submodule.one_eq_range]
#align is_localization.coe_submodule_top IsLocalization.coeSubmodule_top
@[simp]
theorem coeSubmodule_sup (I J : Ideal R) :
coeSubmodule S (I ⊔ J) = coeSubmodule S I ⊔ coeSubmodule S J :=
Submodule.map_sup _ _ _
#align is_localization.coe_submodule_sup IsLocalization.coeSubmodule_sup
@[simp]
theorem coeSubmodule_mul (I J : Ideal R) :
coeSubmodule S (I * J) = coeSubmodule S I * coeSubmodule S J :=
Submodule.map_mul _ _ (Algebra.ofId R S)
#align is_localization.coe_submodule_mul IsLocalization.coeSubmodule_mul
theorem coeSubmodule_fg (hS : Function.Injective (algebraMap R S)) (I : Ideal R) :
Submodule.FG (coeSubmodule S I) ↔ Submodule.FG I :=
⟨Submodule.fg_of_fg_map _ (LinearMap.ker_eq_bot.mpr hS), Submodule.FG.map _⟩
#align is_localization.coe_submodule_fg IsLocalization.coeSubmodule_fg
@[simp]
theorem coeSubmodule_span (s : Set R) :
coeSubmodule S (Ideal.span s) = Submodule.span R (algebraMap R S '' s) := by
rw [IsLocalization.coeSubmodule, Ideal.span, Submodule.map_span]
rfl
#align is_localization.coe_submodule_span IsLocalization.coeSubmodule_span
-- @[simp] -- Porting note (#10618): simp can prove this
theorem coeSubmodule_span_singleton (x : R) :
coeSubmodule S (Ideal.span {x}) = Submodule.span R {(algebraMap R S) x} := by
rw [coeSubmodule_span, Set.image_singleton]
#align is_localization.coe_submodule_span_singleton IsLocalization.coeSubmodule_span_singleton
variable {g : R →+* P}
variable {T : Submonoid P} (hy : M ≤ T.comap g) {Q : Type*} [CommRing Q]
variable [Algebra P Q] [IsLocalization T Q]
variable [IsLocalization M S]
section
theorem isNoetherianRing (h : IsNoetherianRing R) : IsNoetherianRing S := by
rw [isNoetherianRing_iff, isNoetherian_iff_wellFounded] at h ⊢
exact OrderEmbedding.wellFounded (IsLocalization.orderEmbedding M S).dual h
#align is_localization.is_noetherian_ring IsLocalization.isNoetherianRing
end
variable {S M}
@[mono]
theorem coeSubmodule_le_coeSubmodule (h : M ≤ nonZeroDivisors R) {I J : Ideal R} :
coeSubmodule S I ≤ coeSubmodule S J ↔ I ≤ J :=
-- Note: #8386 had to specify the value of `f` here:
Submodule.map_le_map_iff_of_injective (f := Algebra.linearMap R S) (IsLocalization.injective _ h)
_ _
#align is_localization.coe_submodule_le_coe_submodule IsLocalization.coeSubmodule_le_coeSubmodule
@[mono]
theorem coeSubmodule_strictMono (h : M ≤ nonZeroDivisors R) :
StrictMono (coeSubmodule S : Ideal R → Submodule R S) :=
strictMono_of_le_iff_le fun _ _ => (coeSubmodule_le_coeSubmodule h).symm
#align is_localization.coe_submodule_strict_mono IsLocalization.coeSubmodule_strictMono
variable (S)
theorem coeSubmodule_injective (h : M ≤ nonZeroDivisors R) :
Function.Injective (coeSubmodule S : Ideal R → Submodule R S) :=
injective_of_le_imp_le _ fun hl => (coeSubmodule_le_coeSubmodule h).mp hl
#align is_localization.coe_submodule_injective IsLocalization.coeSubmodule_injective
| Mathlib/RingTheory/Localization/Submodule.lean | 125 | 133 | theorem coeSubmodule_isPrincipal {I : Ideal R} (h : M ≤ nonZeroDivisors R) :
(coeSubmodule S I).IsPrincipal ↔ I.IsPrincipal := by |
constructor <;> rintro ⟨⟨x, hx⟩⟩
· have x_mem : x ∈ coeSubmodule S I := hx.symm ▸ Submodule.mem_span_singleton_self x
obtain ⟨x, _, rfl⟩ := (mem_coeSubmodule _ _).mp x_mem
refine ⟨⟨x, coeSubmodule_injective S h ?_⟩⟩
rw [Ideal.submodule_span_eq, hx, coeSubmodule_span_singleton]
· refine ⟨⟨algebraMap R S x, ?_⟩⟩
rw [hx, Ideal.submodule_span_eq, coeSubmodule_span_singleton]
|
/-
Copyright (c) 2022 Yury Kudryashov. All rights reserved.
Released under Apache 2.0 license as described in the file LICENSE.
Authors: Yury Kudryashov
-/
import Mathlib.MeasureTheory.Integral.IntervalIntegral
import Mathlib.MeasureTheory.Integral.Average
#align_import measure_theory.integral.interval_average from "leanprover-community/mathlib"@"9003f28797c0664a49e4179487267c494477d853"
/-!
# Integral average over an interval
In this file we introduce notation `⨍ x in a..b, f x` for the average `⨍ x in Ι a b, f x` of `f`
over the interval `Ι a b = Set.Ioc (min a b) (max a b)` w.r.t. the Lebesgue measure, then prove
formulas for this average:
* `interval_average_eq`: `⨍ x in a..b, f x = (b - a)⁻¹ • ∫ x in a..b, f x`;
* `interval_average_eq_div`: `⨍ x in a..b, f x = (∫ x in a..b, f x) / (b - a)`.
We also prove that `⨍ x in a..b, f x = ⨍ x in b..a, f x`, see `interval_average_symm`.
## Notation
`⨍ x in a..b, f x`: average of `f` over the interval `Ι a b` w.r.t. the Lebesgue measure.
-/
open MeasureTheory Set TopologicalSpace
open scoped Interval
variable {E : Type*} [NormedAddCommGroup E] [NormedSpace ℝ E] [CompleteSpace E]
notation3 "⨍ "(...)" in "a".."b",
"r:60:(scoped f => average (Measure.restrict volume (uIoc a b)) f) => r
| Mathlib/MeasureTheory/Integral/IntervalAverage.lean | 39 | 40 | theorem interval_average_symm (f : ℝ → E) (a b : ℝ) : (⨍ x in a..b, f x) = ⨍ x in b..a, f x := by |
rw [setAverage_eq, setAverage_eq, uIoc_comm]
|
/-
Copyright (c) 2021 Scott Morrison. All rights reserved.
Released under Apache 2.0 license as described in the file LICENSE.
Authors: Scott Morrison, Heather Macbeth
-/
import Mathlib.Algebra.Algebra.Subalgebra.Unitization
import Mathlib.Analysis.RCLike.Basic
import Mathlib.Topology.Algebra.StarSubalgebra
import Mathlib.Topology.ContinuousFunction.ContinuousMapZero
import Mathlib.Topology.ContinuousFunction.Weierstrass
#align_import topology.continuous_function.stone_weierstrass from "leanprover-community/mathlib"@"16e59248c0ebafabd5d071b1cd41743eb8698ffb"
/-!
# The Stone-Weierstrass theorem
If a subalgebra `A` of `C(X, ℝ)`, where `X` is a compact topological space,
separates points, then it is dense.
We argue as follows.
* In any subalgebra `A` of `C(X, ℝ)`, if `f ∈ A`, then `abs f ∈ A.topologicalClosure`.
This follows from the Weierstrass approximation theorem on `[-‖f‖, ‖f‖]` by
approximating `abs` uniformly thereon by polynomials.
* This ensures that `A.topologicalClosure` is actually a sublattice:
if it contains `f` and `g`, then it contains the pointwise supremum `f ⊔ g`
and the pointwise infimum `f ⊓ g`.
* Any nonempty sublattice `L` of `C(X, ℝ)` which separates points is dense,
by a nice argument approximating a given `f` above and below using separating functions.
For each `x y : X`, we pick a function `g x y ∈ L` so `g x y x = f x` and `g x y y = f y`.
By continuity these functions remain close to `f` on small patches around `x` and `y`.
We use compactness to identify a certain finitely indexed infimum of finitely indexed supremums
which is then close to `f` everywhere, obtaining the desired approximation.
* Finally we put these pieces together. `L = A.topologicalClosure` is a nonempty sublattice
which separates points since `A` does, and so is dense (in fact equal to `⊤`).
We then prove the complex version for star subalgebras `A`, by separately approximating
the real and imaginary parts using the real subalgebra of real-valued functions in `A`
(which still separates points, by taking the norm-square of a separating function).
## Future work
Extend to cover the case of subalgebras of the continuous functions vanishing at infinity,
on non-compact spaces.
-/
noncomputable section
namespace ContinuousMap
variable {X : Type*} [TopologicalSpace X] [CompactSpace X]
open scoped Polynomial
/-- Turn a function `f : C(X, ℝ)` into a continuous map into `Set.Icc (-‖f‖) (‖f‖)`,
thereby explicitly attaching bounds.
-/
def attachBound (f : C(X, ℝ)) : C(X, Set.Icc (-‖f‖) ‖f‖) where
toFun x := ⟨f x, ⟨neg_norm_le_apply f x, apply_le_norm f x⟩⟩
#align continuous_map.attach_bound ContinuousMap.attachBound
@[simp]
theorem attachBound_apply_coe (f : C(X, ℝ)) (x : X) : ((attachBound f) x : ℝ) = f x :=
rfl
#align continuous_map.attach_bound_apply_coe ContinuousMap.attachBound_apply_coe
theorem polynomial_comp_attachBound (A : Subalgebra ℝ C(X, ℝ)) (f : A) (g : ℝ[X]) :
(g.toContinuousMapOn (Set.Icc (-‖f‖) ‖f‖)).comp (f : C(X, ℝ)).attachBound =
Polynomial.aeval f g := by
ext
simp only [ContinuousMap.coe_comp, Function.comp_apply, ContinuousMap.attachBound_apply_coe,
Polynomial.toContinuousMapOn_apply, Polynomial.aeval_subalgebra_coe,
Polynomial.aeval_continuousMap_apply, Polynomial.toContinuousMap_apply]
-- This used to be `rw`, but we need `erw` after leanprover/lean4#2644
erw [ContinuousMap.attachBound_apply_coe]
#align continuous_map.polynomial_comp_attach_bound ContinuousMap.polynomial_comp_attachBound
/-- Given a continuous function `f` in a subalgebra of `C(X, ℝ)`, postcomposing by a polynomial
gives another function in `A`.
This lemma proves something slightly more subtle than this:
we take `f`, and think of it as a function into the restricted target `Set.Icc (-‖f‖) ‖f‖)`,
and then postcompose with a polynomial function on that interval.
This is in fact the same situation as above, and so also gives a function in `A`.
-/
theorem polynomial_comp_attachBound_mem (A : Subalgebra ℝ C(X, ℝ)) (f : A) (g : ℝ[X]) :
(g.toContinuousMapOn (Set.Icc (-‖f‖) ‖f‖)).comp (f : C(X, ℝ)).attachBound ∈ A := by
rw [polynomial_comp_attachBound]
apply SetLike.coe_mem
#align continuous_map.polynomial_comp_attach_bound_mem ContinuousMap.polynomial_comp_attachBound_mem
| Mathlib/Topology/ContinuousFunction/StoneWeierstrass.lean | 94 | 113 | theorem comp_attachBound_mem_closure (A : Subalgebra ℝ C(X, ℝ)) (f : A)
(p : C(Set.Icc (-‖f‖) ‖f‖, ℝ)) : p.comp (attachBound (f : C(X, ℝ))) ∈ A.topologicalClosure := by |
-- `p` itself is in the closure of polynomials, by the Weierstrass theorem,
have mem_closure : p ∈ (polynomialFunctions (Set.Icc (-‖f‖) ‖f‖)).topologicalClosure :=
continuousMap_mem_polynomialFunctions_closure _ _ p
-- and so there are polynomials arbitrarily close.
have frequently_mem_polynomials := mem_closure_iff_frequently.mp mem_closure
-- To prove `p.comp (attachBound f)` is in the closure of `A`,
-- we show there are elements of `A` arbitrarily close.
apply mem_closure_iff_frequently.mpr
-- To show that, we pull back the polynomials close to `p`,
refine
((compRightContinuousMap ℝ (attachBound (f : C(X, ℝ)))).continuousAt
p).tendsto.frequently_map
_ ?_ frequently_mem_polynomials
-- but need to show that those pullbacks are actually in `A`.
rintro _ ⟨g, ⟨-, rfl⟩⟩
simp only [SetLike.mem_coe, AlgHom.coe_toRingHom, compRightContinuousMap_apply,
Polynomial.toContinuousMapOnAlgHom_apply]
apply polynomial_comp_attachBound_mem
|
/-
Copyright (c) 2016 Jeremy Avigad. All rights reserved.
Released under Apache 2.0 license as described in the file LICENSE.
Authors: Jeremy Avigad, Leonardo de Moura, Mario Carneiro, Johannes Hölzl
-/
import Mathlib.Algebra.Order.Monoid.Defs
import Mathlib.Algebra.Order.Sub.Defs
import Mathlib.Util.AssertExists
#align_import algebra.order.group.defs from "leanprover-community/mathlib"@"b599f4e4e5cf1fbcb4194503671d3d9e569c1fce"
/-!
# Ordered groups
This file develops the basics of ordered groups.
## Implementation details
Unfortunately, the number of `'` appended to lemmas in this file
may differ between the multiplicative and the additive version of a lemma.
The reason is that we did not want to change existing names in the library.
-/
open Function
universe u
variable {α : Type u}
/-- An ordered additive commutative group is an additive commutative group
with a partial order in which addition is strictly monotone. -/
class OrderedAddCommGroup (α : Type u) extends AddCommGroup α, PartialOrder α where
/-- Addition is monotone in an ordered additive commutative group. -/
protected add_le_add_left : ∀ a b : α, a ≤ b → ∀ c : α, c + a ≤ c + b
#align ordered_add_comm_group OrderedAddCommGroup
/-- An ordered commutative group is a commutative group
with a partial order in which multiplication is strictly monotone. -/
class OrderedCommGroup (α : Type u) extends CommGroup α, PartialOrder α where
/-- Multiplication is monotone in an ordered commutative group. -/
protected mul_le_mul_left : ∀ a b : α, a ≤ b → ∀ c : α, c * a ≤ c * b
#align ordered_comm_group OrderedCommGroup
attribute [to_additive] OrderedCommGroup
@[to_additive]
instance OrderedCommGroup.to_covariantClass_left_le (α : Type u) [OrderedCommGroup α] :
CovariantClass α α (· * ·) (· ≤ ·) where
elim a b c bc := OrderedCommGroup.mul_le_mul_left b c bc a
#align ordered_comm_group.to_covariant_class_left_le OrderedCommGroup.to_covariantClass_left_le
#align ordered_add_comm_group.to_covariant_class_left_le OrderedAddCommGroup.to_covariantClass_left_le
-- See note [lower instance priority]
@[to_additive OrderedAddCommGroup.toOrderedCancelAddCommMonoid]
instance (priority := 100) OrderedCommGroup.toOrderedCancelCommMonoid [OrderedCommGroup α] :
OrderedCancelCommMonoid α :=
{ ‹OrderedCommGroup α› with le_of_mul_le_mul_left := fun a b c ↦ le_of_mul_le_mul_left' }
#align ordered_comm_group.to_ordered_cancel_comm_monoid OrderedCommGroup.toOrderedCancelCommMonoid
#align ordered_add_comm_group.to_ordered_cancel_add_comm_monoid OrderedAddCommGroup.toOrderedCancelAddCommMonoid
example (α : Type u) [OrderedAddCommGroup α] : CovariantClass α α (swap (· + ·)) (· < ·) :=
IsRightCancelAdd.covariant_swap_add_lt_of_covariant_swap_add_le α
-- Porting note: this instance is not used,
-- and causes timeouts after lean4#2210.
-- It was introduced in https://github.com/leanprover-community/mathlib/pull/17564
-- but without the motivation clearly explained.
/-- A choice-free shortcut instance. -/
@[to_additive "A choice-free shortcut instance."]
| Mathlib/Algebra/Order/Group/Defs.lean | 71 | 73 | theorem OrderedCommGroup.to_contravariantClass_left_le (α : Type u) [OrderedCommGroup α] :
ContravariantClass α α (· * ·) (· ≤ ·) where
elim a b c bc := by | simpa using mul_le_mul_left' bc a⁻¹
|
/-
Copyright (c) 2021 Eric Wieser. All rights reserved.
Released under Apache 2.0 license as described in the file LICENSE.
Authors: Eric Wieser, Kevin Buzzard, Jujian Zhang
-/
import Mathlib.Algebra.DirectSum.Algebra
import Mathlib.Algebra.DirectSum.Decomposition
import Mathlib.Algebra.DirectSum.Internal
import Mathlib.Algebra.DirectSum.Ring
#align_import ring_theory.graded_algebra.basic from "leanprover-community/mathlib"@"70fd9563a21e7b963887c9360bd29b2393e6225a"
/-!
# Internally-graded rings and algebras
This file defines the typeclass `GradedAlgebra 𝒜`, for working with an algebra `A` that is
internally graded by a collection of submodules `𝒜 : ι → Submodule R A`.
See the docstring of that typeclass for more information.
## Main definitions
* `GradedRing 𝒜`: the typeclass, which is a combination of `SetLike.GradedMonoid`, and
`DirectSum.Decomposition 𝒜`.
* `GradedAlgebra 𝒜`: A convenience alias for `GradedRing` when `𝒜` is a family of submodules.
* `DirectSum.decomposeRingEquiv 𝒜 : A ≃ₐ[R] ⨁ i, 𝒜 i`, a more bundled version of
`DirectSum.decompose 𝒜`.
* `DirectSum.decomposeAlgEquiv 𝒜 : A ≃ₐ[R] ⨁ i, 𝒜 i`, a more bundled version of
`DirectSum.decompose 𝒜`.
* `GradedAlgebra.proj 𝒜 i` is the linear map from `A` to its degree `i : ι` component, such that
`proj 𝒜 i x = decompose 𝒜 x i`.
## Implementation notes
For now, we do not have internally-graded semirings and internally-graded rings; these can be
represented with `𝒜 : ι → Submodule ℕ A` and `𝒜 : ι → Submodule ℤ A` respectively, since all
`Semiring`s are ℕ-algebras via `algebraNat`, and all `Ring`s are `ℤ`-algebras via `algebraInt`.
## Tags
graded algebra, graded ring, graded semiring, decomposition
-/
open DirectSum
variable {ι R A σ : Type*}
section GradedRing
variable [DecidableEq ι] [AddMonoid ι] [CommSemiring R] [Semiring A] [Algebra R A]
variable [SetLike σ A] [AddSubmonoidClass σ A] (𝒜 : ι → σ)
open DirectSum
/-- An internally-graded `R`-algebra `A` is one that can be decomposed into a collection
of `Submodule R A`s indexed by `ι` such that the canonical map `A → ⨁ i, 𝒜 i` is bijective and
respects multiplication, i.e. the product of an element of degree `i` and an element of degree `j`
is an element of degree `i + j`.
Note that the fact that `A` is internally-graded, `GradedAlgebra 𝒜`, implies an externally-graded
algebra structure `DirectSum.GAlgebra R (fun i ↦ ↥(𝒜 i))`, which in turn makes available an
`Algebra R (⨁ i, 𝒜 i)` instance.
-/
class GradedRing (𝒜 : ι → σ) extends SetLike.GradedMonoid 𝒜, DirectSum.Decomposition 𝒜
#align graded_ring GradedRing
variable [GradedRing 𝒜]
namespace DirectSum
/-- If `A` is graded by `ι` with degree `i` component `𝒜 i`, then it is isomorphic as
a ring to a direct sum of components. -/
def decomposeRingEquiv : A ≃+* ⨁ i, 𝒜 i :=
RingEquiv.symm
{ (decomposeAddEquiv 𝒜).symm with
map_mul' := (coeRingHom 𝒜).map_mul }
#align direct_sum.decompose_ring_equiv DirectSum.decomposeRingEquiv
@[simp]
theorem decompose_one : decompose 𝒜 (1 : A) = 1 :=
map_one (decomposeRingEquiv 𝒜)
#align direct_sum.decompose_one DirectSum.decompose_one
@[simp]
theorem decompose_symm_one : (decompose 𝒜).symm 1 = (1 : A) :=
map_one (decomposeRingEquiv 𝒜).symm
#align direct_sum.decompose_symm_one DirectSum.decompose_symm_one
@[simp]
theorem decompose_mul (x y : A) : decompose 𝒜 (x * y) = decompose 𝒜 x * decompose 𝒜 y :=
map_mul (decomposeRingEquiv 𝒜) x y
#align direct_sum.decompose_mul DirectSum.decompose_mul
@[simp]
theorem decompose_symm_mul (x y : ⨁ i, 𝒜 i) :
(decompose 𝒜).symm (x * y) = (decompose 𝒜).symm x * (decompose 𝒜).symm y :=
map_mul (decomposeRingEquiv 𝒜).symm x y
#align direct_sum.decompose_symm_mul DirectSum.decompose_symm_mul
end DirectSum
/-- The projection maps of a graded ring -/
def GradedRing.proj (i : ι) : A →+ A :=
(AddSubmonoidClass.subtype (𝒜 i)).comp <|
(DFinsupp.evalAddMonoidHom i).comp <|
RingHom.toAddMonoidHom <| RingEquiv.toRingHom <| DirectSum.decomposeRingEquiv 𝒜
#align graded_ring.proj GradedRing.proj
@[simp]
theorem GradedRing.proj_apply (i : ι) (r : A) :
GradedRing.proj 𝒜 i r = (decompose 𝒜 r : ⨁ i, 𝒜 i) i :=
rfl
#align graded_ring.proj_apply GradedRing.proj_apply
| Mathlib/RingTheory/GradedAlgebra/Basic.lean | 115 | 117 | theorem GradedRing.proj_recompose (a : ⨁ i, 𝒜 i) (i : ι) :
GradedRing.proj 𝒜 i ((decompose 𝒜).symm a) = (decompose 𝒜).symm (DirectSum.of _ i (a i)) := by |
rw [GradedRing.proj_apply, decompose_symm_of, Equiv.apply_symm_apply]
|
/-
Copyright (c) 2020 Riccardo Brasca. All rights reserved.
Released under Apache 2.0 license as described in the file LICENSE.
Authors: Riccardo Brasca
-/
import Mathlib.Algebra.NeZero
import Mathlib.Algebra.Polynomial.BigOperators
import Mathlib.Algebra.Polynomial.Lifts
import Mathlib.Algebra.Polynomial.Splits
import Mathlib.RingTheory.RootsOfUnity.Complex
import Mathlib.NumberTheory.ArithmeticFunction
import Mathlib.RingTheory.RootsOfUnity.Basic
import Mathlib.FieldTheory.RatFunc.AsPolynomial
#align_import ring_theory.polynomial.cyclotomic.basic from "leanprover-community/mathlib"@"7fdeecc0d03cd40f7a165e6cf00a4d2286db599f"
/-!
# Cyclotomic polynomials.
For `n : ℕ` and an integral domain `R`, we define a modified version of the `n`-th cyclotomic
polynomial with coefficients in `R`, denoted `cyclotomic' n R`, as `∏ (X - μ)`, where `μ` varies
over the primitive `n`th roots of unity. If there is a primitive `n`th root of unity in `R` then
this the standard definition. We then define the standard cyclotomic polynomial `cyclotomic n R`
with coefficients in any ring `R`.
## Main definition
* `cyclotomic n R` : the `n`-th cyclotomic polynomial with coefficients in `R`.
## Main results
* `Polynomial.degree_cyclotomic` : The degree of `cyclotomic n` is `totient n`.
* `Polynomial.prod_cyclotomic_eq_X_pow_sub_one` : `X ^ n - 1 = ∏ (cyclotomic i)`, where `i`
divides `n`.
* `Polynomial.cyclotomic_eq_prod_X_pow_sub_one_pow_moebius` : The Möbius inversion formula for
`cyclotomic n R` over an abstract fraction field for `R[X]`.
## Implementation details
Our definition of `cyclotomic' n R` makes sense in any integral domain `R`, but the interesting
results hold if there is a primitive `n`-th root of unity in `R`. In particular, our definition is
not the standard one unless there is a primitive `n`th root of unity in `R`. For example,
`cyclotomic' 3 ℤ = 1`, since there are no primitive cube roots of unity in `ℤ`. The main example is
`R = ℂ`, we decided to work in general since the difficulties are essentially the same.
To get the standard cyclotomic polynomials, we use `unique_int_coeff_of_cycl`, with `R = ℂ`,
to get a polynomial with integer coefficients and then we map it to `R[X]`, for any ring `R`.
-/
open scoped Polynomial
noncomputable section
universe u
namespace Polynomial
section Cyclotomic'
section IsDomain
variable {R : Type*} [CommRing R] [IsDomain R]
/-- The modified `n`-th cyclotomic polynomial with coefficients in `R`, it is the usual cyclotomic
polynomial if there is a primitive `n`-th root of unity in `R`. -/
def cyclotomic' (n : ℕ) (R : Type*) [CommRing R] [IsDomain R] : R[X] :=
∏ μ ∈ primitiveRoots n R, (X - C μ)
#align polynomial.cyclotomic' Polynomial.cyclotomic'
/-- The zeroth modified cyclotomic polyomial is `1`. -/
@[simp]
theorem cyclotomic'_zero (R : Type*) [CommRing R] [IsDomain R] : cyclotomic' 0 R = 1 := by
simp only [cyclotomic', Finset.prod_empty, primitiveRoots_zero]
#align polynomial.cyclotomic'_zero Polynomial.cyclotomic'_zero
/-- The first modified cyclotomic polyomial is `X - 1`. -/
@[simp]
theorem cyclotomic'_one (R : Type*) [CommRing R] [IsDomain R] : cyclotomic' 1 R = X - 1 := by
simp only [cyclotomic', Finset.prod_singleton, RingHom.map_one,
IsPrimitiveRoot.primitiveRoots_one]
#align polynomial.cyclotomic'_one Polynomial.cyclotomic'_one
/-- The second modified cyclotomic polyomial is `X + 1` if the characteristic of `R` is not `2`. -/
@[simp]
theorem cyclotomic'_two (R : Type*) [CommRing R] [IsDomain R] (p : ℕ) [CharP R p] (hp : p ≠ 2) :
cyclotomic' 2 R = X + 1 := by
rw [cyclotomic']
have prim_root_two : primitiveRoots 2 R = {(-1 : R)} := by
simp only [Finset.eq_singleton_iff_unique_mem, mem_primitiveRoots two_pos]
exact ⟨IsPrimitiveRoot.neg_one p hp, fun x => IsPrimitiveRoot.eq_neg_one_of_two_right⟩
simp only [prim_root_two, Finset.prod_singleton, RingHom.map_neg, RingHom.map_one, sub_neg_eq_add]
#align polynomial.cyclotomic'_two Polynomial.cyclotomic'_two
/-- `cyclotomic' n R` is monic. -/
theorem cyclotomic'.monic (n : ℕ) (R : Type*) [CommRing R] [IsDomain R] :
(cyclotomic' n R).Monic :=
monic_prod_of_monic _ _ fun _ _ => monic_X_sub_C _
#align polynomial.cyclotomic'.monic Polynomial.cyclotomic'.monic
/-- `cyclotomic' n R` is different from `0`. -/
theorem cyclotomic'_ne_zero (n : ℕ) (R : Type*) [CommRing R] [IsDomain R] : cyclotomic' n R ≠ 0 :=
(cyclotomic'.monic n R).ne_zero
#align polynomial.cyclotomic'_ne_zero Polynomial.cyclotomic'_ne_zero
/-- The natural degree of `cyclotomic' n R` is `totient n` if there is a primitive root of
unity in `R`. -/
| Mathlib/RingTheory/Polynomial/Cyclotomic/Basic.lean | 107 | 114 | theorem natDegree_cyclotomic' {ζ : R} {n : ℕ} (h : IsPrimitiveRoot ζ n) :
(cyclotomic' n R).natDegree = Nat.totient n := by |
rw [cyclotomic']
rw [natDegree_prod (primitiveRoots n R) fun z : R => X - C z]
· simp only [IsPrimitiveRoot.card_primitiveRoots h, mul_one, natDegree_X_sub_C, Nat.cast_id,
Finset.sum_const, nsmul_eq_mul]
intro z _
exact X_sub_C_ne_zero z
|
/-
Copyright (c) 2024 Jiecheng Zhao. All rights reserved.
Released under Apache 2.0 license as described in the file LICENSE.
Authors: Jiecheng Zhao
-/
/-!
# Lemmas about `Array.extract`
Some useful lemmas about Array.extract
-/
set_option autoImplicit true
namespace Array
@[simp]
theorem extract_eq_nil_of_start_eq_end {a : Array α} :
a.extract i i = #[] := by
refine extract_empty_of_stop_le_start a ?h
exact Nat.le_refl i
theorem extract_append_left {a b : Array α} {i j : Nat} (h : j ≤ a.size) :
(a ++ b).extract i j = a.extract i j := by
apply ext
· simp only [size_extract, size_append]
omega
· intro h1 h2 h3
rw [get_extract, get_append_left, get_extract]
theorem extract_append_right {a b : Array α} {i j : Nat} (h : a.size ≤ i) :
(a ++ b).extract i j = b.extract (i - a.size) (j - a.size) := by
apply ext
· rw [size_extract, size_extract, size_append]
omega
· intro k hi h2
rw [get_extract, get_extract,
get_append_right (show size a ≤ i + k by omega)]
congr
omega
| Mathlib/Data/Array/ExtractLemmas.lean | 40 | 42 | theorem extract_eq_of_size_le_end {a : Array α} (h : a.size ≤ l) :
a.extract p l = a.extract p a.size := by |
simp only [extract, Nat.min_eq_right h, Nat.sub_eq, mkEmpty_eq, Nat.min_self]
|
/-
Copyright (c) 2022 Violeta Hernández Palacios. All rights reserved.
Released under Apache 2.0 license as described in the file LICENSE.
Authors: Violeta Hernández Palacios
-/
import Mathlib.Order.SuccPred.Basic
import Mathlib.Order.BoundedOrder
#align_import order.succ_pred.limit from "leanprover-community/mathlib"@"1e05171a5e8cf18d98d9cf7b207540acb044acae"
/-!
# Successor and predecessor limits
We define the predicate `Order.IsSuccLimit` for "successor limits", values that don't cover any
others. They are so named since they can't be the successors of anything smaller. We define
`Order.IsPredLimit` analogously, and prove basic results.
## Todo
The plan is to eventually replace `Ordinal.IsLimit` and `Cardinal.IsLimit` with the common
predicate `Order.IsSuccLimit`.
-/
variable {α : Type*}
namespace Order
open Function Set OrderDual
/-! ### Successor limits -/
section LT
variable [LT α]
/-- A successor limit is a value that doesn't cover any other.
It's so named because in a successor order, a successor limit can't be the successor of anything
smaller. -/
def IsSuccLimit (a : α) : Prop :=
∀ b, ¬b ⋖ a
#align order.is_succ_limit Order.IsSuccLimit
| Mathlib/Order/SuccPred/Limit.lean | 46 | 47 | theorem not_isSuccLimit_iff_exists_covBy (a : α) : ¬IsSuccLimit a ↔ ∃ b, b ⋖ a := by |
simp [IsSuccLimit]
|
/-
Copyright (c) 2014 Jeremy Avigad. All rights reserved.
Released under Apache 2.0 license as described in the file LICENSE.
Authors: Jeremy Avigad, Leonardo de Moura
-/
import Mathlib.Algebra.BigOperators.Group.Finset
#align_import data.nat.gcd.big_operators from "leanprover-community/mathlib"@"008205aa645b3f194c1da47025c5f110c8406eab"
/-! # Lemmas about coprimality with big products.
These lemmas are kept separate from `Data.Nat.GCD.Basic` in order to minimize imports.
-/
namespace Nat
variable {ι : Type*}
theorem coprime_list_prod_left_iff {l : List ℕ} {k : ℕ} :
Coprime l.prod k ↔ ∀ n ∈ l, Coprime n k := by
induction l <;> simp [Nat.coprime_mul_iff_left, *]
theorem coprime_list_prod_right_iff {k : ℕ} {l : List ℕ} :
Coprime k l.prod ↔ ∀ n ∈ l, Coprime k n := by
simp_rw [coprime_comm (n := k), coprime_list_prod_left_iff]
theorem coprime_multiset_prod_left_iff {m : Multiset ℕ} {k : ℕ} :
Coprime m.prod k ↔ ∀ n ∈ m, Coprime n k := by
induction m using Quotient.inductionOn; simpa using coprime_list_prod_left_iff
theorem coprime_multiset_prod_right_iff {k : ℕ} {m : Multiset ℕ} :
Coprime k m.prod ↔ ∀ n ∈ m, Coprime k n := by
induction m using Quotient.inductionOn; simpa using coprime_list_prod_right_iff
theorem coprime_prod_left_iff {t : Finset ι} {s : ι → ℕ} {x : ℕ} :
Coprime (∏ i ∈ t, s i) x ↔ ∀ i ∈ t, Coprime (s i) x := by
simpa using coprime_multiset_prod_left_iff (m := t.val.map s)
theorem coprime_prod_right_iff {x : ℕ} {t : Finset ι} {s : ι → ℕ} :
Coprime x (∏ i ∈ t, s i) ↔ ∀ i ∈ t, Coprime x (s i) := by
simpa using coprime_multiset_prod_right_iff (m := t.val.map s)
/-- See `IsCoprime.prod_left` for the corresponding lemma about `IsCoprime` -/
alias ⟨_, Coprime.prod_left⟩ := coprime_prod_left_iff
#align nat.coprime_prod_left Nat.Coprime.prod_left
/-- See `IsCoprime.prod_right` for the corresponding lemma about `IsCoprime` -/
alias ⟨_, Coprime.prod_right⟩ := coprime_prod_right_iff
#align nat.coprime_prod_right Nat.Coprime.prod_right
theorem coprime_fintype_prod_left_iff [Fintype ι] {s : ι → ℕ} {x : ℕ} :
Coprime (∏ i, s i) x ↔ ∀ i, Coprime (s i) x := by
simp [coprime_prod_left_iff]
| Mathlib/Data/Nat/GCD/BigOperators.lean | 56 | 58 | theorem coprime_fintype_prod_right_iff [Fintype ι] {x : ℕ} {s : ι → ℕ} :
Coprime x (∏ i, s i) ↔ ∀ i, Coprime x (s i) := by |
simp [coprime_prod_right_iff]
|
/-
Copyright (c) 2021 Kexing Ying. All rights reserved.
Released under Apache 2.0 license as described in the file LICENSE.
Authors: Kexing Ying
-/
import Mathlib.MeasureTheory.Measure.VectorMeasure
import Mathlib.MeasureTheory.Function.AEEqOfIntegral
#align_import measure_theory.measure.with_density_vector_measure from "leanprover-community/mathlib"@"d1bd9c5df2867c1cb463bc6364446d57bdd9f7f1"
/-!
# Vector measure defined by an integral
Given a measure `μ` and an integrable function `f : α → E`, we can define a vector measure `v` such
that for all measurable set `s`, `v i = ∫ x in s, f x ∂μ`. This definition is useful for
the Radon-Nikodym theorem for signed measures.
## Main definitions
* `MeasureTheory.Measure.withDensityᵥ`: the vector measure formed by integrating a function `f`
with respect to a measure `μ` on some set if `f` is integrable, and `0` otherwise.
-/
noncomputable section
open scoped Classical MeasureTheory NNReal ENNReal
variable {α β : Type*} {m : MeasurableSpace α}
namespace MeasureTheory
open TopologicalSpace
variable {μ ν : Measure α}
variable {E : Type*} [NormedAddCommGroup E] [NormedSpace ℝ E] [CompleteSpace E]
/-- Given a measure `μ` and an integrable function `f`, `μ.withDensityᵥ f` is
the vector measure which maps the set `s` to `∫ₛ f ∂μ`. -/
def Measure.withDensityᵥ {m : MeasurableSpace α} (μ : Measure α) (f : α → E) : VectorMeasure α E :=
if hf : Integrable f μ then
{ measureOf' := fun s => if MeasurableSet s then ∫ x in s, f x ∂μ else 0
empty' := by simp
not_measurable' := fun s hs => if_neg hs
m_iUnion' := fun s hs₁ hs₂ => by
dsimp only
convert hasSum_integral_iUnion hs₁ hs₂ hf.integrableOn with n
· rw [if_pos (hs₁ n)]
· rw [if_pos (MeasurableSet.iUnion hs₁)] }
else 0
#align measure_theory.measure.with_densityᵥ MeasureTheory.Measure.withDensityᵥ
open Measure
variable {f g : α → E}
theorem withDensityᵥ_apply (hf : Integrable f μ) {s : Set α} (hs : MeasurableSet s) :
μ.withDensityᵥ f s = ∫ x in s, f x ∂μ := by rw [withDensityᵥ, dif_pos hf]; exact dif_pos hs
#align measure_theory.with_densityᵥ_apply MeasureTheory.withDensityᵥ_apply
@[simp]
| Mathlib/MeasureTheory/Measure/WithDensityVectorMeasure.lean | 64 | 65 | theorem withDensityᵥ_zero : μ.withDensityᵥ (0 : α → E) = 0 := by |
ext1 s hs; erw [withDensityᵥ_apply (integrable_zero α E μ) hs]; simp
|
/-
Copyright (c) 2022 Aaron Anderson. All rights reserved.
Released under Apache 2.0 license as described in the file LICENSE.
Authors: Aaron Anderson
-/
import Mathlib.ModelTheory.Satisfiability
import Mathlib.Combinatorics.SimpleGraph.Basic
#align_import model_theory.graph from "leanprover-community/mathlib"@"e56b8fea84d60fe434632b9d3b829ee685fb0c8f"
/-!
# First-Order Structures in Graph Theory
This file defines first-order languages, structures, and theories in graph theory.
## Main Definitions
* `FirstOrder.Language.graph` is the language consisting of a single relation representing
adjacency.
* `SimpleGraph.structure` is the first-order structure corresponding to a given simple graph.
* `FirstOrder.Language.Theory.simpleGraph` is the theory of simple graphs.
* `FirstOrder.Language.simpleGraphOfStructure` gives the simple graph corresponding to a model
of the theory of simple graphs.
-/
set_option linter.uppercaseLean3 false
universe u v w w'
namespace FirstOrder
namespace Language
open FirstOrder
open Structure
variable {L : Language.{u, v}} {α : Type w} {V : Type w'} {n : ℕ}
/-! ### Simple Graphs -/
/-- The language consisting of a single relation representing adjacency. -/
protected def graph : Language :=
Language.mk₂ Empty Empty Empty Empty Unit
#align first_order.language.graph FirstOrder.Language.graph
/-- The symbol representing the adjacency relation. -/
def adj : Language.graph.Relations 2 :=
Unit.unit
#align first_order.language.adj FirstOrder.Language.adj
/-- Any simple graph can be thought of as a structure in the language of graphs. -/
def _root_.SimpleGraph.structure (G : SimpleGraph V) : Language.graph.Structure V :=
Structure.mk₂ Empty.elim Empty.elim Empty.elim Empty.elim fun _ => G.Adj
#align simple_graph.Structure SimpleGraph.structure
namespace graph
instance instIsRelational : IsRelational Language.graph :=
Language.isRelational_mk₂
#align first_order.language.graph.first_order.language.is_relational FirstOrder.Language.graph.instIsRelational
instance instSubsingleton : Subsingleton (Language.graph.Relations n) :=
Language.subsingleton_mk₂_relations
#align first_order.language.graph.relations.subsingleton FirstOrder.Language.graph.instSubsingleton
end graph
/-- The theory of simple graphs. -/
protected def Theory.simpleGraph : Language.graph.Theory :=
{adj.irreflexive, adj.symmetric}
#align first_order.language.Theory.simple_graph FirstOrder.Language.Theory.simpleGraph
@[simp]
theorem Theory.simpleGraph_model_iff [Language.graph.Structure V] :
V ⊨ Theory.simpleGraph ↔
(Irreflexive fun x y : V => RelMap adj ![x, y]) ∧
Symmetric fun x y : V => RelMap adj ![x, y] := by
simp [Theory.simpleGraph]
#align first_order.language.Theory.simple_graph_model_iff FirstOrder.Language.Theory.simpleGraph_model_iff
instance simpleGraph_model (G : SimpleGraph V) :
@Theory.Model _ V G.structure Theory.simpleGraph := by
simp only [@Theory.simpleGraph_model_iff _ G.structure, relMap_apply₂]
exact ⟨G.loopless, G.symm⟩
#align first_order.language.simple_graph_model FirstOrder.Language.simpleGraph_model
variable (V)
/-- Any model of the theory of simple graphs represents a simple graph. -/
@[simps]
def simpleGraphOfStructure [Language.graph.Structure V] [V ⊨ Theory.simpleGraph] :
SimpleGraph V where
Adj x y := RelMap adj ![x, y]
symm :=
Relations.realize_symmetric.1
(Theory.realize_sentence_of_mem Theory.simpleGraph
(Set.mem_insert_of_mem _ (Set.mem_singleton _)))
loopless :=
Relations.realize_irreflexive.1
(Theory.realize_sentence_of_mem Theory.simpleGraph (Set.mem_insert _ _))
#align first_order.language.simple_graph_of_structure FirstOrder.Language.simpleGraphOfStructure
variable {V}
@[simp]
| Mathlib/ModelTheory/Graph.lean | 107 | 110 | theorem _root_.SimpleGraph.simpleGraphOfStructure (G : SimpleGraph V) :
@simpleGraphOfStructure V G.structure _ = G := by |
ext
rfl
|
/-
Copyright (c) 2021 Oliver Nash. All rights reserved.
Released under Apache 2.0 license as described in the file LICENSE.
Authors: Oliver Nash
-/
import Mathlib.Analysis.NormedSpace.ContinuousAffineMap
import Mathlib.Analysis.Calculus.ContDiff.Basic
#align_import analysis.calculus.affine_map from "leanprover-community/mathlib"@"839b92fedff9981cf3fe1c1f623e04b0d127f57c"
/-!
# Smooth affine maps
This file contains results about smoothness of affine maps.
## Main definitions:
* `ContinuousAffineMap.contDiff`: a continuous affine map is smooth
-/
namespace ContinuousAffineMap
variable {𝕜 V W : Type*} [NontriviallyNormedField 𝕜]
variable [NormedAddCommGroup V] [NormedSpace 𝕜 V]
variable [NormedAddCommGroup W] [NormedSpace 𝕜 W]
/-- A continuous affine map between normed vector spaces is smooth. -/
| Mathlib/Analysis/Calculus/AffineMap.lean | 30 | 33 | theorem contDiff {n : ℕ∞} (f : V →ᴬ[𝕜] W) : ContDiff 𝕜 n f := by |
rw [f.decomp]
apply f.contLinear.contDiff.add
exact contDiff_const
|
/-
Copyright (c) 2021 Sébastien Gouëzel. All rights reserved.
Released under Apache 2.0 license as described in the file LICENSE.
Authors: Johannes Hölzl, Yury Kudryashov, Sébastien Gouëzel
-/
import Mathlib.MeasureTheory.Constructions.BorelSpace.Order
import Mathlib.Topology.Order.LeftRightLim
#align_import measure_theory.measure.stieltjes from "leanprover-community/mathlib"@"20d5763051978e9bc6428578ed070445df6a18b3"
/-!
# Stieltjes measures on the real line
Consider a function `f : ℝ → ℝ` which is monotone and right-continuous. Then one can define a
corresponding measure, giving mass `f b - f a` to the interval `(a, b]`.
## Main definitions
* `StieltjesFunction` is a structure containing a function from `ℝ → ℝ`, together with the
assertions that it is monotone and right-continuous. To `f : StieltjesFunction`, one associates
a Borel measure `f.measure`.
* `f.measure_Ioc` asserts that `f.measure (Ioc a b) = ofReal (f b - f a)`
* `f.measure_Ioo` asserts that `f.measure (Ioo a b) = ofReal (leftLim f b - f a)`.
* `f.measure_Icc` and `f.measure_Ico` are analogous.
-/
noncomputable section
open scoped Classical
open Set Filter Function ENNReal NNReal Topology MeasureTheory
open ENNReal (ofReal)
/-! ### Basic properties of Stieltjes functions -/
/-- Bundled monotone right-continuous real functions, used to construct Stieltjes measures. -/
structure StieltjesFunction where
toFun : ℝ → ℝ
mono' : Monotone toFun
right_continuous' : ∀ x, ContinuousWithinAt toFun (Ici x) x
#align stieltjes_function StieltjesFunction
#align stieltjes_function.to_fun StieltjesFunction.toFun
#align stieltjes_function.mono' StieltjesFunction.mono'
#align stieltjes_function.right_continuous' StieltjesFunction.right_continuous'
namespace StieltjesFunction
attribute [coe] toFun
instance instCoeFun : CoeFun StieltjesFunction fun _ => ℝ → ℝ :=
⟨toFun⟩
#align stieltjes_function.has_coe_to_fun StieltjesFunction.instCoeFun
initialize_simps_projections StieltjesFunction (toFun → apply)
@[ext] lemma ext {f g : StieltjesFunction} (h : ∀ x, f x = g x) : f = g := by
exact (StieltjesFunction.mk.injEq ..).mpr (funext (by exact h))
variable (f : StieltjesFunction)
theorem mono : Monotone f :=
f.mono'
#align stieltjes_function.mono StieltjesFunction.mono
theorem right_continuous (x : ℝ) : ContinuousWithinAt f (Ici x) x :=
f.right_continuous' x
#align stieltjes_function.right_continuous StieltjesFunction.right_continuous
theorem rightLim_eq (f : StieltjesFunction) (x : ℝ) : Function.rightLim f x = f x := by
rw [← f.mono.continuousWithinAt_Ioi_iff_rightLim_eq, continuousWithinAt_Ioi_iff_Ici]
exact f.right_continuous' x
#align stieltjes_function.right_lim_eq StieltjesFunction.rightLim_eq
| Mathlib/MeasureTheory/Measure/Stieltjes.lean | 76 | 80 | theorem iInf_Ioi_eq (f : StieltjesFunction) (x : ℝ) : ⨅ r : Ioi x, f r = f x := by |
suffices Function.rightLim f x = ⨅ r : Ioi x, f r by rw [← this, f.rightLim_eq]
rw [f.mono.rightLim_eq_sInf, sInf_image']
rw [← neBot_iff]
infer_instance
|
/-
Copyright (c) 2020 Sébastien Gouëzel. All rights reserved.
Released under Apache 2.0 license as described in the file LICENSE.
Authors: Sébastien Gouëzel, Yury Kudryashov
-/
import Mathlib.Analysis.Calculus.Deriv.Inv
import Mathlib.Analysis.Calculus.Deriv.Polynomial
import Mathlib.Analysis.SpecialFunctions.ExpDeriv
import Mathlib.Analysis.SpecialFunctions.PolynomialExp
#align_import analysis.calculus.bump_function_inner from "leanprover-community/mathlib"@"3bce8d800a6f2b8f63fe1e588fd76a9ff4adcebe"
/-!
# Infinitely smooth transition function
In this file we construct two infinitely smooth functions with properties that an analytic function
cannot have:
* `expNegInvGlue` is equal to zero for `x ≤ 0` and is strictly positive otherwise; it is given by
`x ↦ exp (-1/x)` for `x > 0`;
* `Real.smoothTransition` is equal to zero for `x ≤ 0` and is equal to one for `x ≥ 1`; it is given
by `expNegInvGlue x / (expNegInvGlue x + expNegInvGlue (1 - x))`;
-/
noncomputable section
open scoped Classical Topology
open Polynomial Real Filter Set Function
open scoped Polynomial
/-- `expNegInvGlue` is the real function given by `x ↦ exp (-1/x)` for `x > 0` and `0`
for `x ≤ 0`. It is a basic building block to construct smooth partitions of unity. Its main property
is that it vanishes for `x ≤ 0`, it is positive for `x > 0`, and the junction between the two
behaviors is flat enough to retain smoothness. The fact that this function is `C^∞` is proved in
`expNegInvGlue.contDiff`. -/
def expNegInvGlue (x : ℝ) : ℝ :=
if x ≤ 0 then 0 else exp (-x⁻¹)
#align exp_neg_inv_glue expNegInvGlue
namespace expNegInvGlue
/-- The function `expNegInvGlue` vanishes on `(-∞, 0]`. -/
| Mathlib/Analysis/SpecialFunctions/SmoothTransition.lean | 46 | 46 | theorem zero_of_nonpos {x : ℝ} (hx : x ≤ 0) : expNegInvGlue x = 0 := by | simp [expNegInvGlue, hx]
|
/-
Copyright (c) 2020 Sébastien Gouëzel. All rights reserved.
Released under Apache 2.0 license as described in the file LICENSE.
Authors: Sébastien Gouëzel
-/
import Mathlib.Analysis.Calculus.Deriv.Basic
import Mathlib.Analysis.Calculus.ContDiff.Defs
#align_import analysis.calculus.iterated_deriv from "leanprover-community/mathlib"@"3bce8d800a6f2b8f63fe1e588fd76a9ff4adcebe"
/-!
# One-dimensional iterated derivatives
We define the `n`-th derivative of a function `f : 𝕜 → F` as a function
`iteratedDeriv n f : 𝕜 → F`, as well as a version on domains `iteratedDerivWithin n f s : 𝕜 → F`,
and prove their basic properties.
## Main definitions and results
Let `𝕜` be a nontrivially normed field, and `F` a normed vector space over `𝕜`. Let `f : 𝕜 → F`.
* `iteratedDeriv n f` is the `n`-th derivative of `f`, seen as a function from `𝕜` to `F`.
It is defined as the `n`-th Fréchet derivative (which is a multilinear map) applied to the
vector `(1, ..., 1)`, to take advantage of all the existing framework, but we show that it
coincides with the naive iterative definition.
* `iteratedDeriv_eq_iterate` states that the `n`-th derivative of `f` is obtained by starting
from `f` and differentiating it `n` times.
* `iteratedDerivWithin n f s` is the `n`-th derivative of `f` within the domain `s`. It only
behaves well when `s` has the unique derivative property.
* `iteratedDerivWithin_eq_iterate` states that the `n`-th derivative of `f` in the domain `s` is
obtained by starting from `f` and differentiating it `n` times within `s`. This only holds when
`s` has the unique derivative property.
## Implementation details
The results are deduced from the corresponding results for the more general (multilinear) iterated
Fréchet derivative. For this, we write `iteratedDeriv n f` as the composition of
`iteratedFDeriv 𝕜 n f` and a continuous linear equiv. As continuous linear equivs respect
differentiability and commute with differentiation, this makes it possible to prove readily that
the derivative of the `n`-th derivative is the `n+1`-th derivative in `iteratedDerivWithin_succ`,
by translating the corresponding result `iteratedFDerivWithin_succ_apply_left` for the
iterated Fréchet derivative.
-/
noncomputable section
open scoped Classical Topology
open Filter Asymptotics Set
variable {𝕜 : Type*} [NontriviallyNormedField 𝕜]
variable {F : Type*} [NormedAddCommGroup F] [NormedSpace 𝕜 F]
variable {E : Type*} [NormedAddCommGroup E] [NormedSpace 𝕜 E]
/-- The `n`-th iterated derivative of a function from `𝕜` to `F`, as a function from `𝕜` to `F`. -/
def iteratedDeriv (n : ℕ) (f : 𝕜 → F) (x : 𝕜) : F :=
(iteratedFDeriv 𝕜 n f x : (Fin n → 𝕜) → F) fun _ : Fin n => 1
#align iterated_deriv iteratedDeriv
/-- The `n`-th iterated derivative of a function from `𝕜` to `F` within a set `s`, as a function
from `𝕜` to `F`. -/
def iteratedDerivWithin (n : ℕ) (f : 𝕜 → F) (s : Set 𝕜) (x : 𝕜) : F :=
(iteratedFDerivWithin 𝕜 n f s x : (Fin n → 𝕜) → F) fun _ : Fin n => 1
#align iterated_deriv_within iteratedDerivWithin
variable {n : ℕ} {f : 𝕜 → F} {s : Set 𝕜} {x : 𝕜}
theorem iteratedDerivWithin_univ : iteratedDerivWithin n f univ = iteratedDeriv n f := by
ext x
rw [iteratedDerivWithin, iteratedDeriv, iteratedFDerivWithin_univ]
#align iterated_deriv_within_univ iteratedDerivWithin_univ
/-! ### Properties of the iterated derivative within a set -/
theorem iteratedDerivWithin_eq_iteratedFDerivWithin : iteratedDerivWithin n f s x =
(iteratedFDerivWithin 𝕜 n f s x : (Fin n → 𝕜) → F) fun _ : Fin n => 1 :=
rfl
#align iterated_deriv_within_eq_iterated_fderiv_within iteratedDerivWithin_eq_iteratedFDerivWithin
/-- Write the iterated derivative as the composition of a continuous linear equiv and the iterated
Fréchet derivative -/
theorem iteratedDerivWithin_eq_equiv_comp : iteratedDerivWithin n f s =
(ContinuousMultilinearMap.piFieldEquiv 𝕜 (Fin n) F).symm ∘ iteratedFDerivWithin 𝕜 n f s := by
ext x; rfl
#align iterated_deriv_within_eq_equiv_comp iteratedDerivWithin_eq_equiv_comp
/-- Write the iterated Fréchet derivative as the composition of a continuous linear equiv and the
iterated derivative. -/
| Mathlib/Analysis/Calculus/IteratedDeriv/Defs.lean | 91 | 95 | theorem iteratedFDerivWithin_eq_equiv_comp :
iteratedFDerivWithin 𝕜 n f s =
ContinuousMultilinearMap.piFieldEquiv 𝕜 (Fin n) F ∘ iteratedDerivWithin n f s := by |
rw [iteratedDerivWithin_eq_equiv_comp, ← Function.comp.assoc, LinearIsometryEquiv.self_comp_symm,
Function.id_comp]
|
/-
Copyright (c) 2018 Chris Hughes. All rights reserved.
Released under Apache 2.0 license as described in the file LICENSE.
Authors: Chris Hughes, Johannes Hölzl, Scott Morrison, Jens Wagemaker, Johan Commelin
-/
import Mathlib.Algebra.Polynomial.AlgebraMap
import Mathlib.Algebra.Polynomial.BigOperators
import Mathlib.Algebra.Polynomial.Degree.Lemmas
import Mathlib.Algebra.Polynomial.Div
#align_import data.polynomial.ring_division from "leanprover-community/mathlib"@"8efcf8022aac8e01df8d302dcebdbc25d6a886c8"
/-!
# Theory of univariate polynomials
We prove basic results about univariate polynomials.
-/
noncomputable section
open Polynomial
open Finset
namespace Polynomial
universe u v w z
variable {R : Type u} {S : Type v} {T : Type w} {a b : R} {n : ℕ}
section CommRing
variable [CommRing R] {p q : R[X]}
section
variable [Semiring S]
theorem natDegree_pos_of_aeval_root [Algebra R S] {p : R[X]} (hp : p ≠ 0) {z : S}
(hz : aeval z p = 0) (inj : ∀ x : R, algebraMap R S x = 0 → x = 0) : 0 < p.natDegree :=
natDegree_pos_of_eval₂_root hp (algebraMap R S) hz inj
#align polynomial.nat_degree_pos_of_aeval_root Polynomial.natDegree_pos_of_aeval_root
theorem degree_pos_of_aeval_root [Algebra R S] {p : R[X]} (hp : p ≠ 0) {z : S} (hz : aeval z p = 0)
(inj : ∀ x : R, algebraMap R S x = 0 → x = 0) : 0 < p.degree :=
natDegree_pos_iff_degree_pos.mp (natDegree_pos_of_aeval_root hp hz inj)
#align polynomial.degree_pos_of_aeval_root Polynomial.degree_pos_of_aeval_root
theorem modByMonic_eq_of_dvd_sub (hq : q.Monic) {p₁ p₂ : R[X]} (h : q ∣ p₁ - p₂) :
p₁ %ₘ q = p₂ %ₘ q := by
nontriviality R
obtain ⟨f, sub_eq⟩ := h
refine (div_modByMonic_unique (p₂ /ₘ q + f) _ hq ⟨?_, degree_modByMonic_lt _ hq⟩).2
rw [sub_eq_iff_eq_add.mp sub_eq, mul_add, ← add_assoc, modByMonic_add_div _ hq, add_comm]
#align polynomial.mod_by_monic_eq_of_dvd_sub Polynomial.modByMonic_eq_of_dvd_sub
theorem add_modByMonic (p₁ p₂ : R[X]) : (p₁ + p₂) %ₘ q = p₁ %ₘ q + p₂ %ₘ q := by
by_cases hq : q.Monic
· cases' subsingleton_or_nontrivial R with hR hR
· simp only [eq_iff_true_of_subsingleton]
· exact
(div_modByMonic_unique (p₁ /ₘ q + p₂ /ₘ q) _ hq
⟨by
rw [mul_add, add_left_comm, add_assoc, modByMonic_add_div _ hq, ← add_assoc,
add_comm (q * _), modByMonic_add_div _ hq],
(degree_add_le _ _).trans_lt
(max_lt (degree_modByMonic_lt _ hq) (degree_modByMonic_lt _ hq))⟩).2
· simp_rw [modByMonic_eq_of_not_monic _ hq]
#align polynomial.add_mod_by_monic Polynomial.add_modByMonic
theorem smul_modByMonic (c : R) (p : R[X]) : c • p %ₘ q = c • (p %ₘ q) := by
by_cases hq : q.Monic
· cases' subsingleton_or_nontrivial R with hR hR
· simp only [eq_iff_true_of_subsingleton]
· exact
(div_modByMonic_unique (c • (p /ₘ q)) (c • (p %ₘ q)) hq
⟨by rw [mul_smul_comm, ← smul_add, modByMonic_add_div p hq],
(degree_smul_le _ _).trans_lt (degree_modByMonic_lt _ hq)⟩).2
· simp_rw [modByMonic_eq_of_not_monic _ hq]
#align polynomial.smul_mod_by_monic Polynomial.smul_modByMonic
/-- `_ %ₘ q` as an `R`-linear map. -/
@[simps]
def modByMonicHom (q : R[X]) : R[X] →ₗ[R] R[X] where
toFun p := p %ₘ q
map_add' := add_modByMonic
map_smul' := smul_modByMonic
#align polynomial.mod_by_monic_hom Polynomial.modByMonicHom
theorem neg_modByMonic (p mod : R[X]) : (-p) %ₘ mod = - (p %ₘ mod) :=
(modByMonicHom mod).map_neg p
theorem sub_modByMonic (a b mod : R[X]) : (a - b) %ₘ mod = a %ₘ mod - b %ₘ mod :=
(modByMonicHom mod).map_sub a b
end
section
variable [Ring S]
theorem aeval_modByMonic_eq_self_of_root [Algebra R S] {p q : R[X]} (hq : q.Monic) {x : S}
(hx : aeval x q = 0) : aeval x (p %ₘ q) = aeval x p := by
--`eval₂_modByMonic_eq_self_of_root` doesn't work here as it needs commutativity
rw [modByMonic_eq_sub_mul_div p hq, _root_.map_sub, _root_.map_mul, hx, zero_mul,
sub_zero]
#align polynomial.aeval_mod_by_monic_eq_self_of_root Polynomial.aeval_modByMonic_eq_self_of_root
end
end CommRing
section NoZeroDivisors
variable [Semiring R] [NoZeroDivisors R] {p q : R[X]}
instance : NoZeroDivisors R[X] where
eq_zero_or_eq_zero_of_mul_eq_zero h := by
rw [← leadingCoeff_eq_zero, ← leadingCoeff_eq_zero]
refine eq_zero_or_eq_zero_of_mul_eq_zero ?_
rw [← leadingCoeff_zero, ← leadingCoeff_mul, h]
| Mathlib/Algebra/Polynomial/RingDivision.lean | 124 | 126 | theorem natDegree_mul (hp : p ≠ 0) (hq : q ≠ 0) : (p*q).natDegree = p.natDegree + q.natDegree := by |
rw [← Nat.cast_inj (R := WithBot ℕ), ← degree_eq_natDegree (mul_ne_zero hp hq),
Nat.cast_add, ← degree_eq_natDegree hp, ← degree_eq_natDegree hq, degree_mul]
|
/-
Copyright (c) 2022 Joël Riou. All rights reserved.
Released under Apache 2.0 license as described in the file LICENSE.
Authors: Joël Riou
-/
import Mathlib.CategoryTheory.Equivalence
#align_import algebraic_topology.dold_kan.compatibility from "leanprover-community/mathlib"@"32a7e535287f9c73f2e4d2aef306a39190f0b504"
/-! Tools for compatibilities between Dold-Kan equivalences
The purpose of this file is to introduce tools which will enable the
construction of the Dold-Kan equivalence `SimplicialObject C ≌ ChainComplex C ℕ`
for a pseudoabelian category `C` from the equivalence
`Karoubi (SimplicialObject C) ≌ Karoubi (ChainComplex C ℕ)` and the two
equivalences `simplicial_object C ≅ Karoubi (SimplicialObject C)` and
`ChainComplex C ℕ ≅ Karoubi (ChainComplex C ℕ)`.
It is certainly possible to get an equivalence `SimplicialObject C ≌ ChainComplex C ℕ`
using a compositions of the three equivalences above, but then neither the functor
nor the inverse would have good definitional properties. For example, it would be better
if the inverse functor of the equivalence was exactly the functor
`Γ₀ : SimplicialObject C ⥤ ChainComplex C ℕ` which was constructed in `FunctorGamma.lean`.
In this file, given four categories `A`, `A'`, `B`, `B'`, equivalences `eA : A ≅ A'`,
`eB : B ≅ B'`, `e' : A' ≅ B'`, functors `F : A ⥤ B'`, `G : B ⥤ A` equipped with certain
compatibilities, we construct successive equivalences:
- `equivalence₀` from `A` to `B'`, which is the composition of `eA` and `e'`.
- `equivalence₁` from `A` to `B'`, with the same inverse functor as `equivalence₀`,
but whose functor is `F`.
- `equivalence₂` from `A` to `B`, which is the composition of `equivalence₁` and the
inverse of `eB`:
- `equivalence` from `A` to `B`, which has the same functor `F ⋙ eB.inverse` as `equivalence₂`,
but whose inverse functor is `G`.
When extra assumptions are given, we shall also provide simplification lemmas for the
unit and counit isomorphisms of `equivalence`.
(See `Equivalence.lean` for the general strategy of proof of the Dold-Kan equivalence.)
-/
open CategoryTheory CategoryTheory.Category
namespace AlgebraicTopology
namespace DoldKan
namespace Compatibility
variable {A A' B B' : Type*} [Category A] [Category A'] [Category B] [Category B'] (eA : A ≌ A')
(eB : B ≌ B') (e' : A' ≌ B') {F : A ⥤ B'} (hF : eA.functor ⋙ e'.functor ≅ F) {G : B ⥤ A}
(hG : eB.functor ⋙ e'.inverse ≅ G ⋙ eA.functor)
/-- A basic equivalence `A ≅ B'` obtained by composing `eA : A ≅ A'` and `e' : A' ≅ B'`. -/
@[simps! functor inverse unitIso_hom_app]
def equivalence₀ : A ≌ B' :=
eA.trans e'
#align algebraic_topology.dold_kan.compatibility.equivalence₀ AlgebraicTopology.DoldKan.Compatibility.equivalence₀
variable {eA} {e'}
/-- An intermediate equivalence `A ≅ B'` whose functor is `F` and whose inverse is
`e'.inverse ⋙ eA.inverse`. -/
@[simps! functor]
def equivalence₁ : A ≌ B' := (equivalence₀ eA e').changeFunctor hF
#align algebraic_topology.dold_kan.compatibility.equivalence₁ AlgebraicTopology.DoldKan.Compatibility.equivalence₁
theorem equivalence₁_inverse : (equivalence₁ hF).inverse = e'.inverse ⋙ eA.inverse :=
rfl
#align algebraic_topology.dold_kan.compatibility.equivalence₁_inverse AlgebraicTopology.DoldKan.Compatibility.equivalence₁_inverse
/-- The counit isomorphism of the equivalence `equivalence₁` between `A` and `B'`. -/
@[simps!]
def equivalence₁CounitIso : (e'.inverse ⋙ eA.inverse) ⋙ F ≅ 𝟭 B' :=
calc
(e'.inverse ⋙ eA.inverse) ⋙ F ≅ (e'.inverse ⋙ eA.inverse) ⋙ eA.functor ⋙ e'.functor :=
isoWhiskerLeft _ hF.symm
_ ≅ e'.inverse ⋙ (eA.inverse ⋙ eA.functor) ⋙ e'.functor := Iso.refl _
_ ≅ e'.inverse ⋙ 𝟭 _ ⋙ e'.functor := isoWhiskerLeft _ (isoWhiskerRight eA.counitIso _)
_ ≅ e'.inverse ⋙ e'.functor := Iso.refl _
_ ≅ 𝟭 B' := e'.counitIso
#align algebraic_topology.dold_kan.compatibility.equivalence₁_counit_iso AlgebraicTopology.DoldKan.Compatibility.equivalence₁CounitIso
theorem equivalence₁CounitIso_eq : (equivalence₁ hF).counitIso = equivalence₁CounitIso hF := by
ext Y
simp [equivalence₁, equivalence₀]
#align algebraic_topology.dold_kan.compatibility.equivalence₁_counit_iso_eq AlgebraicTopology.DoldKan.Compatibility.equivalence₁CounitIso_eq
/-- The unit isomorphism of the equivalence `equivalence₁` between `A` and `B'`. -/
@[simps!]
def equivalence₁UnitIso : 𝟭 A ≅ F ⋙ e'.inverse ⋙ eA.inverse :=
calc
𝟭 A ≅ eA.functor ⋙ eA.inverse := eA.unitIso
_ ≅ eA.functor ⋙ 𝟭 A' ⋙ eA.inverse := Iso.refl _
_ ≅ eA.functor ⋙ (e'.functor ⋙ e'.inverse) ⋙ eA.inverse :=
isoWhiskerLeft _ (isoWhiskerRight e'.unitIso _)
_ ≅ (eA.functor ⋙ e'.functor) ⋙ e'.inverse ⋙ eA.inverse := Iso.refl _
_ ≅ F ⋙ e'.inverse ⋙ eA.inverse := isoWhiskerRight hF _
#align algebraic_topology.dold_kan.compatibility.equivalence₁_unit_iso AlgebraicTopology.DoldKan.Compatibility.equivalence₁UnitIso
| Mathlib/AlgebraicTopology/DoldKan/Compatibility.lean | 103 | 105 | theorem equivalence₁UnitIso_eq : (equivalence₁ hF).unitIso = equivalence₁UnitIso hF := by |
ext X
simp [equivalence₁]
|
/-
Copyright (c) 2021 Riccardo Brasca. All rights reserved.
Released under Apache 2.0 license as described in the file LICENSE.
Authors: Riccardo Brasca
-/
import Mathlib.LinearAlgebra.FreeModule.Finite.Basic
import Mathlib.LinearAlgebra.Matrix.Charpoly.Coeff
import Mathlib.FieldTheory.Minpoly.Field
#align_import linear_algebra.charpoly.basic from "leanprover-community/mathlib"@"d3e8e0a0237c10c2627bf52c246b15ff8e7df4c0"
/-!
# Characteristic polynomial
We define the characteristic polynomial of `f : M →ₗ[R] M`, where `M` is a finite and
free `R`-module. The proof that `f.charpoly` is the characteristic polynomial of the matrix of `f`
in any basis is in `LinearAlgebra/Charpoly/ToMatrix`.
## Main definition
* `LinearMap.charpoly f` : the characteristic polynomial of `f : M →ₗ[R] M`.
-/
universe u v w
variable {R : Type u} {M : Type v} [CommRing R] [Nontrivial R]
variable [AddCommGroup M] [Module R M] [Module.Free R M] [Module.Finite R M] (f : M →ₗ[R] M)
open Matrix Polynomial
noncomputable section
open Module.Free Polynomial Matrix
namespace LinearMap
section Basic
/-- The characteristic polynomial of `f : M →ₗ[R] M`. -/
def charpoly : R[X] :=
(toMatrix (chooseBasis R M) (chooseBasis R M) f).charpoly
#align linear_map.charpoly LinearMap.charpoly
theorem charpoly_def : f.charpoly = (toMatrix (chooseBasis R M) (chooseBasis R M) f).charpoly :=
rfl
#align linear_map.charpoly_def LinearMap.charpoly_def
end Basic
section Coeff
theorem charpoly_monic : f.charpoly.Monic :=
Matrix.charpoly_monic _
#align linear_map.charpoly_monic LinearMap.charpoly_monic
open FiniteDimensional in
lemma charpoly_natDegree [StrongRankCondition R] : natDegree (charpoly f) = finrank R M := by
rw [charpoly, Matrix.charpoly_natDegree_eq_dim, finrank_eq_card_chooseBasisIndex]
end Coeff
section CayleyHamilton
/-- The **Cayley-Hamilton Theorem**, that the characteristic polynomial of a linear map, applied
to the linear map itself, is zero.
See `Matrix.aeval_self_charpoly` for the equivalent statement about matrices. -/
| Mathlib/LinearAlgebra/Charpoly/Basic.lean | 71 | 75 | theorem aeval_self_charpoly : aeval f f.charpoly = 0 := by |
apply (LinearEquiv.map_eq_zero_iff (algEquivMatrix (chooseBasis R M)).toLinearEquiv).1
rw [AlgEquiv.toLinearEquiv_apply, ← AlgEquiv.coe_algHom, ← Polynomial.aeval_algHom_apply _ _ _,
charpoly_def]
exact Matrix.aeval_self_charpoly _
|
/-
Copyright (c) 2021 Anne Baanen. All rights reserved.
Released under Apache 2.0 license as described in the file LICENSE.
Authors: Anne Baanen
-/
import Mathlib.FieldTheory.RatFunc.AsPolynomial
import Mathlib.RingTheory.EuclideanDomain
import Mathlib.RingTheory.Localization.FractionRing
import Mathlib.RingTheory.Polynomial.Content
/-!
# The degree of rational functions
## Main definitions
We define the degree of a rational function, with values in `ℤ`:
- `intDegree` is the degree of a rational function, defined as the difference between the
`natDegree` of its numerator and the `natDegree` of its denominator. In particular,
`intDegree 0 = 0`.
-/
noncomputable section
universe u
variable {K : Type u}
namespace RatFunc
section IntDegree
open Polynomial
variable [Field K]
/-- `intDegree x` is the degree of the rational function `x`, defined as the difference between
the `natDegree` of its numerator and the `natDegree` of its denominator. In particular,
`intDegree 0 = 0`. -/
def intDegree (x : RatFunc K) : ℤ :=
natDegree x.num - natDegree x.denom
#align ratfunc.int_degree RatFunc.intDegree
@[simp]
theorem intDegree_zero : intDegree (0 : RatFunc K) = 0 := by
rw [intDegree, num_zero, natDegree_zero, denom_zero, natDegree_one, sub_self]
#align ratfunc.int_degree_zero RatFunc.intDegree_zero
@[simp]
theorem intDegree_one : intDegree (1 : RatFunc K) = 0 := by
rw [intDegree, num_one, denom_one, sub_self]
#align ratfunc.int_degree_one RatFunc.intDegree_one
@[simp]
theorem intDegree_C (k : K) : intDegree (C k) = 0 := by
rw [intDegree, num_C, natDegree_C, denom_C, natDegree_one, sub_self]
set_option linter.uppercaseLean3 false in #align ratfunc.int_degree_C RatFunc.intDegree_C
@[simp]
theorem intDegree_X : intDegree (X : RatFunc K) = 1 := by
rw [intDegree, num_X, Polynomial.natDegree_X, denom_X, Polynomial.natDegree_one,
Int.ofNat_one, Int.ofNat_zero, sub_zero]
set_option linter.uppercaseLean3 false in #align ratfunc.int_degree_X RatFunc.intDegree_X
@[simp]
| Mathlib/FieldTheory/RatFunc/Degree.lean | 65 | 68 | theorem intDegree_polynomial {p : K[X]} :
intDegree (algebraMap K[X] (RatFunc K) p) = natDegree p := by |
rw [intDegree, RatFunc.num_algebraMap, RatFunc.denom_algebraMap, Polynomial.natDegree_one,
Int.ofNat_zero, sub_zero]
|
/-
Copyright (c) 2018 Chris Hughes. All rights reserved.
Released under Apache 2.0 license as described in the file LICENSE.
Authors: Chris Hughes, Abhimanyu Pallavi Sudhir, Jean Lo, Calle Sönne, Sébastien Gouëzel,
Rémy Degenne, David Loeffler
-/
import Mathlib.Analysis.SpecialFunctions.Pow.Complex
import Qq
#align_import analysis.special_functions.pow.real from "leanprover-community/mathlib"@"4fa54b337f7d52805480306db1b1439c741848c8"
/-! # Power function on `ℝ`
We construct the power functions `x ^ y`, where `x` and `y` are real numbers.
-/
noncomputable section
open scoped Classical
open Real ComplexConjugate
open Finset Set
/-
## Definitions
-/
namespace Real
variable {x y z : ℝ}
/-- The real power function `x ^ y`, defined as the real part of the complex power function.
For `x > 0`, it is equal to `exp (y log x)`. For `x = 0`, one sets `0 ^ 0=1` and `0 ^ y=0` for
`y ≠ 0`. For `x < 0`, the definition is somewhat arbitrary as it depends on the choice of a complex
determination of the logarithm. With our conventions, it is equal to `exp (y log x) cos (π y)`. -/
noncomputable def rpow (x y : ℝ) :=
((x : ℂ) ^ (y : ℂ)).re
#align real.rpow Real.rpow
noncomputable instance : Pow ℝ ℝ := ⟨rpow⟩
@[simp]
theorem rpow_eq_pow (x y : ℝ) : rpow x y = x ^ y := rfl
#align real.rpow_eq_pow Real.rpow_eq_pow
theorem rpow_def (x y : ℝ) : x ^ y = ((x : ℂ) ^ (y : ℂ)).re := rfl
#align real.rpow_def Real.rpow_def
theorem rpow_def_of_nonneg {x : ℝ} (hx : 0 ≤ x) (y : ℝ) :
x ^ y = if x = 0 then if y = 0 then 1 else 0 else exp (log x * y) := by
simp only [rpow_def, Complex.cpow_def]; split_ifs <;>
simp_all [(Complex.ofReal_log hx).symm, -Complex.ofReal_mul, -RCLike.ofReal_mul,
(Complex.ofReal_mul _ _).symm, Complex.exp_ofReal_re, Complex.ofReal_eq_zero]
#align real.rpow_def_of_nonneg Real.rpow_def_of_nonneg
theorem rpow_def_of_pos {x : ℝ} (hx : 0 < x) (y : ℝ) : x ^ y = exp (log x * y) := by
rw [rpow_def_of_nonneg (le_of_lt hx), if_neg (ne_of_gt hx)]
#align real.rpow_def_of_pos Real.rpow_def_of_pos
theorem exp_mul (x y : ℝ) : exp (x * y) = exp x ^ y := by rw [rpow_def_of_pos (exp_pos _), log_exp]
#align real.exp_mul Real.exp_mul
@[simp, norm_cast]
theorem rpow_intCast (x : ℝ) (n : ℤ) : x ^ (n : ℝ) = x ^ n := by
simp only [rpow_def, ← Complex.ofReal_zpow, Complex.cpow_intCast, Complex.ofReal_intCast,
Complex.ofReal_re]
#align real.rpow_int_cast Real.rpow_intCast
@[deprecated (since := "2024-04-17")]
alias rpow_int_cast := rpow_intCast
@[simp, norm_cast]
theorem rpow_natCast (x : ℝ) (n : ℕ) : x ^ (n : ℝ) = x ^ n := by simpa using rpow_intCast x n
#align real.rpow_nat_cast Real.rpow_natCast
@[deprecated (since := "2024-04-17")]
alias rpow_nat_cast := rpow_natCast
@[simp]
theorem exp_one_rpow (x : ℝ) : exp 1 ^ x = exp x := by rw [← exp_mul, one_mul]
#align real.exp_one_rpow Real.exp_one_rpow
@[simp] lemma exp_one_pow (n : ℕ) : exp 1 ^ n = exp n := by rw [← rpow_natCast, exp_one_rpow]
theorem rpow_eq_zero_iff_of_nonneg (hx : 0 ≤ x) : x ^ y = 0 ↔ x = 0 ∧ y ≠ 0 := by
simp only [rpow_def_of_nonneg hx]
split_ifs <;> simp [*, exp_ne_zero]
#align real.rpow_eq_zero_iff_of_nonneg Real.rpow_eq_zero_iff_of_nonneg
@[simp]
lemma rpow_eq_zero (hx : 0 ≤ x) (hy : y ≠ 0) : x ^ y = 0 ↔ x = 0 := by
simp [rpow_eq_zero_iff_of_nonneg, *]
@[simp]
lemma rpow_ne_zero (hx : 0 ≤ x) (hy : y ≠ 0) : x ^ y ≠ 0 ↔ x ≠ 0 :=
Real.rpow_eq_zero hx hy |>.not
open Real
| Mathlib/Analysis/SpecialFunctions/Pow/Real.lean | 100 | 112 | theorem rpow_def_of_neg {x : ℝ} (hx : x < 0) (y : ℝ) : x ^ y = exp (log x * y) * cos (y * π) := by |
rw [rpow_def, Complex.cpow_def, if_neg]
· have : Complex.log x * y = ↑(log (-x) * y) + ↑(y * π) * Complex.I := by
simp only [Complex.log, abs_of_neg hx, Complex.arg_ofReal_of_neg hx, Complex.abs_ofReal,
Complex.ofReal_mul]
ring
rw [this, Complex.exp_add_mul_I, ← Complex.ofReal_exp, ← Complex.ofReal_cos, ←
Complex.ofReal_sin, mul_add, ← Complex.ofReal_mul, ← mul_assoc, ← Complex.ofReal_mul,
Complex.add_re, Complex.ofReal_re, Complex.mul_re, Complex.I_re, Complex.ofReal_im,
Real.log_neg_eq_log]
ring
· rw [Complex.ofReal_eq_zero]
exact ne_of_lt hx
|
/-
Copyright (c) 2014 Jeremy Avigad. All rights reserved.
Released under Apache 2.0 license as described in the file LICENSE.
Authors: Jeremy Avigad, Leonardo de Moura
-/
import Mathlib.Algebra.GroupWithZero.Divisibility
import Mathlib.Algebra.Order.Ring.Nat
import Mathlib.Tactic.NthRewrite
#align_import data.nat.gcd.basic from "leanprover-community/mathlib"@"e8638a0fcaf73e4500469f368ef9494e495099b3"
/-!
# Definitions and properties of `Nat.gcd`, `Nat.lcm`, and `Nat.coprime`
Generalizations of these are provided in a later file as `GCDMonoid.gcd` and
`GCDMonoid.lcm`.
Note that the global `IsCoprime` is not a straightforward generalization of `Nat.coprime`, see
`Nat.isCoprime_iff_coprime` for the connection between the two.
-/
namespace Nat
/-! ### `gcd` -/
theorem gcd_greatest {a b d : ℕ} (hda : d ∣ a) (hdb : d ∣ b) (hd : ∀ e : ℕ, e ∣ a → e ∣ b → e ∣ d) :
d = a.gcd b :=
(dvd_antisymm (hd _ (gcd_dvd_left a b) (gcd_dvd_right a b)) (dvd_gcd hda hdb)).symm
#align nat.gcd_greatest Nat.gcd_greatest
/-! Lemmas where one argument consists of addition of a multiple of the other -/
@[simp]
theorem gcd_add_mul_right_right (m n k : ℕ) : gcd m (n + k * m) = gcd m n := by
simp [gcd_rec m (n + k * m), gcd_rec m n]
#align nat.gcd_add_mul_right_right Nat.gcd_add_mul_right_right
@[simp]
theorem gcd_add_mul_left_right (m n k : ℕ) : gcd m (n + m * k) = gcd m n := by
simp [gcd_rec m (n + m * k), gcd_rec m n]
#align nat.gcd_add_mul_left_right Nat.gcd_add_mul_left_right
@[simp]
theorem gcd_mul_right_add_right (m n k : ℕ) : gcd m (k * m + n) = gcd m n := by simp [add_comm _ n]
#align nat.gcd_mul_right_add_right Nat.gcd_mul_right_add_right
@[simp]
theorem gcd_mul_left_add_right (m n k : ℕ) : gcd m (m * k + n) = gcd m n := by simp [add_comm _ n]
#align nat.gcd_mul_left_add_right Nat.gcd_mul_left_add_right
@[simp]
theorem gcd_add_mul_right_left (m n k : ℕ) : gcd (m + k * n) n = gcd m n := by
rw [gcd_comm, gcd_add_mul_right_right, gcd_comm]
#align nat.gcd_add_mul_right_left Nat.gcd_add_mul_right_left
@[simp]
theorem gcd_add_mul_left_left (m n k : ℕ) : gcd (m + n * k) n = gcd m n := by
rw [gcd_comm, gcd_add_mul_left_right, gcd_comm]
#align nat.gcd_add_mul_left_left Nat.gcd_add_mul_left_left
@[simp]
theorem gcd_mul_right_add_left (m n k : ℕ) : gcd (k * n + m) n = gcd m n := by
rw [gcd_comm, gcd_mul_right_add_right, gcd_comm]
#align nat.gcd_mul_right_add_left Nat.gcd_mul_right_add_left
@[simp]
| Mathlib/Data/Nat/GCD/Basic.lean | 68 | 69 | theorem gcd_mul_left_add_left (m n k : ℕ) : gcd (n * k + m) n = gcd m n := by |
rw [gcd_comm, gcd_mul_left_add_right, gcd_comm]
|
/-
Copyright (c) 2021 Riccardo Brasca. All rights reserved.
Released under Apache 2.0 license as described in the file LICENSE.
Authors: Riccardo Brasca
-/
import Mathlib.RingTheory.IntegrallyClosed
import Mathlib.RingTheory.Trace
import Mathlib.RingTheory.Norm
#align_import ring_theory.discriminant from "leanprover-community/mathlib"@"3e068ece210655b7b9a9477c3aff38a492400aa1"
/-!
# Discriminant of a family of vectors
Given an `A`-algebra `B` and `b`, an `ι`-indexed family of elements of `B`, we define the
*discriminant* of `b` as the determinant of the matrix whose `(i j)`-th element is the trace of
`b i * b j`.
## Main definition
* `Algebra.discr A b` : the discriminant of `b : ι → B`.
## Main results
* `Algebra.discr_zero_of_not_linearIndependent` : if `b` is not linear independent, then
`Algebra.discr A b = 0`.
* `Algebra.discr_of_matrix_vecMul` and `Algebra.discr_of_matrix_mulVec` : formulas relating
`Algebra.discr A ι b` with `Algebra.discr A (b ᵥ* P.map (algebraMap A B))` and
`Algebra.discr A (P.map (algebraMap A B) *ᵥ b)`.
* `Algebra.discr_not_zero_of_basis` : over a field, if `b` is a basis, then
`Algebra.discr K b ≠ 0`.
* `Algebra.discr_eq_det_embeddingsMatrixReindex_pow_two` : if `L/K` is a field extension and
`b : ι → L`, then `discr K b` is the square of the determinant of the matrix whose `(i, j)`
coefficient is `σⱼ (b i)`, where `σⱼ : L →ₐ[K] E` is the embedding in an algebraically closed
field `E` corresponding to `j : ι` via a bijection `e : ι ≃ (L →ₐ[K] E)`.
* `Algebra.discr_powerBasis_eq_prod` : the discriminant of a power basis.
* `Algebra.discr_isIntegral` : if `K` and `L` are fields and `IsScalarTower R K L`, if
`b : ι → L` satisfies `∀ i, IsIntegral R (b i)`, then `IsIntegral R (discr K b)`.
* `Algebra.discr_mul_isIntegral_mem_adjoin` : let `K` be the fraction field of an integrally
closed domain `R` and let `L` be a finite separable extension of `K`. Let `B : PowerBasis K L`
be such that `IsIntegral R B.gen`. Then for all, `z : L` we have
`(discr K B.basis) • z ∈ adjoin R ({B.gen} : Set L)`.
## Implementation details
Our definition works for any `A`-algebra `B`, but note that if `B` is not free as an `A`-module,
then `trace A B = 0` by definition, so `discr A b = 0` for any `b`.
-/
universe u v w z
open scoped Matrix
open Matrix FiniteDimensional Fintype Polynomial Finset IntermediateField
namespace Algebra
variable (A : Type u) {B : Type v} (C : Type z) {ι : Type w} [DecidableEq ι]
variable [CommRing A] [CommRing B] [Algebra A B] [CommRing C] [Algebra A C]
section Discr
/-- Given an `A`-algebra `B` and `b`, an `ι`-indexed family of elements of `B`, we define
`discr A ι b` as the determinant of `traceMatrix A ι b`. -/
-- Porting note: using `[DecidableEq ι]` instead of `by classical...` did not work in
-- mathlib3.
noncomputable def discr (A : Type u) {B : Type v} [CommRing A] [CommRing B] [Algebra A B]
[Fintype ι] (b : ι → B) := (traceMatrix A b).det
#align algebra.discr Algebra.discr
theorem discr_def [Fintype ι] (b : ι → B) : discr A b = (traceMatrix A b).det := rfl
variable {A C} in
/-- Mapping a family of vectors along an `AlgEquiv` preserves the discriminant. -/
theorem discr_eq_discr_of_algEquiv [Fintype ι] (b : ι → B) (f : B ≃ₐ[A] C) :
Algebra.discr A b = Algebra.discr A (f ∘ b) := by
rw [discr_def]; congr; ext
simp_rw [traceMatrix_apply, traceForm_apply, Function.comp, ← map_mul f, trace_eq_of_algEquiv]
#align algebra.discr_def Algebra.discr_def
variable {ι' : Type*} [Fintype ι'] [Fintype ι] [DecidableEq ι']
section Basic
@[simp]
theorem discr_reindex (b : Basis ι A B) (f : ι ≃ ι') : discr A (b ∘ ⇑f.symm) = discr A b := by
classical rw [← Basis.coe_reindex, discr_def, traceMatrix_reindex, det_reindex_self, ← discr_def]
#align algebra.discr_reindex Algebra.discr_reindex
/-- If `b` is not linear independent, then `Algebra.discr A b = 0`. -/
theorem discr_zero_of_not_linearIndependent [IsDomain A] {b : ι → B}
(hli : ¬LinearIndependent A b) : discr A b = 0 := by
classical
obtain ⟨g, hg, i, hi⟩ := Fintype.not_linearIndependent_iff.1 hli
have : (traceMatrix A b) *ᵥ g = 0 := by
ext i
have : ∀ j, (trace A B) (b i * b j) * g j = (trace A B) (g j • b j * b i) := by
intro j;
simp [mul_comm]
simp only [mulVec, dotProduct, traceMatrix_apply, Pi.zero_apply, traceForm_apply, fun j =>
this j, ← map_sum, ← sum_mul, hg, zero_mul, LinearMap.map_zero]
by_contra h
rw [discr_def] at h
simp [Matrix.eq_zero_of_mulVec_eq_zero h this] at hi
#align algebra.discr_zero_of_not_linear_independent Algebra.discr_zero_of_not_linearIndependent
variable {A}
/-- Relation between `Algebra.discr A ι b` and
`Algebra.discr A (b ᵥ* P.map (algebraMap A B))`. -/
| Mathlib/RingTheory/Discriminant.lean | 113 | 116 | theorem discr_of_matrix_vecMul (b : ι → B) (P : Matrix ι ι A) :
discr A (b ᵥ* P.map (algebraMap A B)) = P.det ^ 2 * discr A b := by |
rw [discr_def, traceMatrix_of_matrix_vecMul, det_mul, det_mul, det_transpose, mul_comm, ←
mul_assoc, discr_def, pow_two]
|
/-
Copyright (c) 2021 Riccardo Brasca. All rights reserved.
Released under Apache 2.0 license as described in the file LICENSE.
Authors: Riccardo Brasca
-/
import Mathlib.LinearAlgebra.Dimension.LinearMap
import Mathlib.LinearAlgebra.FreeModule.StrongRankCondition
#align_import linear_algebra.free_module.finite.matrix from "leanprover-community/mathlib"@"b1c23399f01266afe392a0d8f71f599a0dad4f7b"
/-!
# Finite and free modules using matrices
We provide some instances for finite and free modules involving matrices.
## Main results
* `Module.Free.linearMap` : if `M` and `N` are finite and free, then `M →ₗ[R] N` is free.
* `Module.Finite.ofBasis` : A free module with a basis indexed by a `Fintype` is finite.
* `Module.Finite.linearMap` : if `M` and `N` are finite and free, then `M →ₗ[R] N`
is finite.
-/
universe u u' v w
variable (R : Type u) (S : Type u') (M : Type v) (N : Type w)
open Module.Free (chooseBasis ChooseBasisIndex)
open FiniteDimensional (finrank)
section Ring
variable [Ring R] [Ring S] [AddCommGroup M] [Module R M] [Module.Free R M] [Module.Finite R M]
variable [AddCommGroup N] [Module R N] [Module S N] [SMulCommClass R S N]
private noncomputable def linearMapEquivFun : (M →ₗ[R] N) ≃ₗ[S] ChooseBasisIndex R M → N :=
(chooseBasis R M).repr.congrLeft N S ≪≫ₗ (Finsupp.lsum S).symm ≪≫ₗ
LinearEquiv.piCongrRight fun _ ↦ LinearMap.ringLmapEquivSelf R S N
instance Module.Free.linearMap [Module.Free S N] : Module.Free S (M →ₗ[R] N) :=
Module.Free.of_equiv (linearMapEquivFun R S M N).symm
#align module.free.linear_map Module.Free.linearMap
instance Module.Finite.linearMap [Module.Finite S N] : Module.Finite S (M →ₗ[R] N) :=
Module.Finite.equiv (linearMapEquivFun R S M N).symm
#align module.finite.linear_map Module.Finite.linearMap
variable [StrongRankCondition R] [StrongRankCondition S] [Module.Free S N]
open Cardinal
theorem FiniteDimensional.rank_linearMap :
Module.rank S (M →ₗ[R] N) = lift.{w} (Module.rank R M) * lift.{v} (Module.rank S N) := by
rw [(linearMapEquivFun R S M N).rank_eq, rank_fun_eq_lift_mul,
← finrank_eq_card_chooseBasisIndex, ← finrank_eq_rank R, lift_natCast]
/-- The finrank of `M →ₗ[R] N` as an `S`-module is `(finrank R M) * (finrank S N)`. -/
theorem FiniteDimensional.finrank_linearMap :
finrank S (M →ₗ[R] N) = finrank R M * finrank S N := by
simp_rw [finrank, rank_linearMap, toNat_mul, toNat_lift]
#align finite_dimensional.finrank_linear_map FiniteDimensional.finrank_linearMap
variable [Module R S] [SMulCommClass R S S]
theorem FiniteDimensional.rank_linearMap_self :
Module.rank S (M →ₗ[R] S) = lift.{u'} (Module.rank R M) := by
rw [rank_linearMap, rank_self, lift_one, mul_one]
theorem FiniteDimensional.finrank_linearMap_self : finrank S (M →ₗ[R] S) = finrank R M := by
rw [finrank_linearMap, finrank_self, mul_one]
end Ring
section AlgHom
variable (K M : Type*) (L : Type v) [CommRing K] [Ring M] [Algebra K M]
[Module.Free K M] [Module.Finite K M] [CommRing L] [IsDomain L] [Algebra K L]
instance Finite.algHom : Finite (M →ₐ[K] L) :=
(linearIndependent_algHom_toLinearMap K M L).finite
open Cardinal
| Mathlib/LinearAlgebra/FreeModule/Finite/Matrix.lean | 85 | 89 | theorem cardinal_mk_algHom_le_rank : #(M →ₐ[K] L) ≤ lift.{v} (Module.rank K M) := by |
convert (linearIndependent_algHom_toLinearMap K M L).cardinal_lift_le_rank
· rw [lift_id]
· have := Module.nontrivial K L
rw [lift_id, FiniteDimensional.rank_linearMap_self]
|
/-
Copyright (c) 2018 Mario Carneiro. All rights reserved.
Released under Apache 2.0 license as described in the file LICENSE.
Authors: Mario Carneiro, James Gallicchio
-/
import Batteries.Data.List.Count
import Batteries.Data.Fin.Lemmas
/-!
# Pairwise relations on a list
This file provides basic results about `List.Pairwise` and `List.pwFilter` (definitions are in
`Batteries.Data.List.Basic`).
`Pairwise r [a 0, ..., a (n - 1)]` means `∀ i j, i < j → r (a i) (a j)`. For example,
`Pairwise (≠) l` means that all elements of `l` are distinct, and `Pairwise (<) l` means that `l`
is strictly increasing.
`pwFilter r l` is the list obtained by iteratively adding each element of `l` that doesn't break
the pairwiseness of the list we have so far. It thus yields `l'` a maximal sublist of `l` such that
`Pairwise r l'`.
## Tags
sorted, nodup
-/
open Nat Function
namespace List
/-! ### Pairwise -/
theorem rel_of_pairwise_cons (p : (a :: l).Pairwise R) : ∀ {a'}, a' ∈ l → R a a' :=
(pairwise_cons.1 p).1 _
theorem Pairwise.of_cons (p : (a :: l).Pairwise R) : Pairwise R l :=
(pairwise_cons.1 p).2
theorem Pairwise.tail : ∀ {l : List α} (_p : Pairwise R l), Pairwise R l.tail
| [], h => h
| _ :: _, h => h.of_cons
theorem Pairwise.drop : ∀ {l : List α} {n : Nat}, List.Pairwise R l → List.Pairwise R (l.drop n)
| _, 0, h => h
| [], _ + 1, _ => List.Pairwise.nil
| _ :: _, n + 1, h => Pairwise.drop (n := n) (pairwise_cons.mp h).right
theorem Pairwise.imp_of_mem {S : α → α → Prop}
(H : ∀ {a b}, a ∈ l → b ∈ l → R a b → S a b) (p : Pairwise R l) : Pairwise S l := by
induction p with
| nil => constructor
| @cons a l r _ ih =>
constructor
· exact fun x h => H (mem_cons_self ..) (mem_cons_of_mem _ h) <| r x h
· exact ih fun m m' => H (mem_cons_of_mem _ m) (mem_cons_of_mem _ m')
theorem Pairwise.and (hR : Pairwise R l) (hS : Pairwise S l) :
l.Pairwise fun a b => R a b ∧ S a b := by
induction hR with
| nil => simp only [Pairwise.nil]
| cons R1 _ IH =>
simp only [Pairwise.nil, pairwise_cons] at hS ⊢
exact ⟨fun b bl => ⟨R1 b bl, hS.1 b bl⟩, IH hS.2⟩
theorem pairwise_and_iff : l.Pairwise (fun a b => R a b ∧ S a b) ↔ Pairwise R l ∧ Pairwise S l :=
⟨fun h => ⟨h.imp fun h => h.1, h.imp fun h => h.2⟩, fun ⟨hR, hS⟩ => hR.and hS⟩
theorem Pairwise.imp₂ (H : ∀ a b, R a b → S a b → T a b)
(hR : Pairwise R l) (hS : l.Pairwise S) : l.Pairwise T :=
(hR.and hS).imp fun ⟨h₁, h₂⟩ => H _ _ h₁ h₂
theorem Pairwise.iff_of_mem {S : α → α → Prop} {l : List α}
(H : ∀ {a b}, a ∈ l → b ∈ l → (R a b ↔ S a b)) : Pairwise R l ↔ Pairwise S l :=
⟨Pairwise.imp_of_mem fun m m' => (H m m').1, Pairwise.imp_of_mem fun m m' => (H m m').2⟩
theorem Pairwise.iff {S : α → α → Prop} (H : ∀ a b, R a b ↔ S a b) {l : List α} :
Pairwise R l ↔ Pairwise S l :=
Pairwise.iff_of_mem fun _ _ => H ..
theorem pairwise_of_forall {l : List α} (H : ∀ x y, R x y) : Pairwise R l := by
induction l <;> simp [*]
theorem Pairwise.and_mem {l : List α} :
Pairwise R l ↔ Pairwise (fun x y => x ∈ l ∧ y ∈ l ∧ R x y) l :=
Pairwise.iff_of_mem <| by simp (config := { contextual := true })
theorem Pairwise.imp_mem {l : List α} :
Pairwise R l ↔ Pairwise (fun x y => x ∈ l → y ∈ l → R x y) l :=
Pairwise.iff_of_mem <| by simp (config := { contextual := true })
theorem Pairwise.forall_of_forall_of_flip (h₁ : ∀ x ∈ l, R x x) (h₂ : Pairwise R l)
(h₃ : l.Pairwise (flip R)) : ∀ ⦃x⦄, x ∈ l → ∀ ⦃y⦄, y ∈ l → R x y := by
induction l with
| nil => exact forall_mem_nil _
| cons a l ih =>
rw [pairwise_cons] at h₂ h₃
simp only [mem_cons]
rintro x (rfl | hx) y (rfl | hy)
· exact h₁ _ (l.mem_cons_self _)
· exact h₂.1 _ hy
· exact h₃.1 _ hx
· exact ih (fun x hx => h₁ _ <| mem_cons_of_mem _ hx) h₂.2 h₃.2 hx hy
theorem pairwise_singleton (R) (a : α) : Pairwise R [a] := by simp
theorem pairwise_pair {a b : α} : Pairwise R [a, b] ↔ R a b := by simp
| .lake/packages/batteries/Batteries/Data/List/Pairwise.lean | 108 | 112 | theorem pairwise_append_comm {R : α → α → Prop} (s : ∀ {x y}, R x y → R y x) {l₁ l₂ : List α} :
Pairwise R (l₁ ++ l₂) ↔ Pairwise R (l₂ ++ l₁) := by |
have (l₁ l₂ : List α) (H : ∀ x : α, x ∈ l₁ → ∀ y : α, y ∈ l₂ → R x y)
(x : α) (xm : x ∈ l₂) (y : α) (ym : y ∈ l₁) : R x y := s (H y ym x xm)
simp only [pairwise_append, and_left_comm]; rw [Iff.intro (this l₁ l₂) (this l₂ l₁)]
|
/-
Copyright (c) 2020 Yury Kudryashov. All rights reserved.
Released under Apache 2.0 license as described in the file LICENSE.
Authors: Yury Kudryashov
-/
import Mathlib.Topology.UniformSpace.CompleteSeparated
import Mathlib.Topology.EMetricSpace.Lipschitz
import Mathlib.Topology.MetricSpace.Basic
import Mathlib.Topology.MetricSpace.Bounded
#align_import topology.metric_space.antilipschitz from "leanprover-community/mathlib"@"c8f305514e0d47dfaa710f5a52f0d21b588e6328"
/-!
# Antilipschitz functions
We say that a map `f : α → β` between two (extended) metric spaces is
`AntilipschitzWith K`, `K ≥ 0`, if for all `x, y` we have `edist x y ≤ K * edist (f x) (f y)`.
For a metric space, the latter inequality is equivalent to `dist x y ≤ K * dist (f x) (f y)`.
## Implementation notes
The parameter `K` has type `ℝ≥0`. This way we avoid conjunction in the definition and have
coercions both to `ℝ` and `ℝ≥0∞`. We do not require `0 < K` in the definition, mostly because
we do not have a `posreal` type.
-/
variable {α β γ : Type*}
open scoped NNReal ENNReal Uniformity Topology
open Set Filter Bornology
/-- We say that `f : α → β` is `AntilipschitzWith K` if for any two points `x`, `y` we have
`edist x y ≤ K * edist (f x) (f y)`. -/
def AntilipschitzWith [PseudoEMetricSpace α] [PseudoEMetricSpace β] (K : ℝ≥0) (f : α → β) :=
∀ x y, edist x y ≤ K * edist (f x) (f y)
#align antilipschitz_with AntilipschitzWith
theorem AntilipschitzWith.edist_lt_top [PseudoEMetricSpace α] [PseudoMetricSpace β] {K : ℝ≥0}
{f : α → β} (h : AntilipschitzWith K f) (x y : α) : edist x y < ⊤ :=
(h x y).trans_lt <| ENNReal.mul_lt_top ENNReal.coe_ne_top (edist_ne_top _ _)
#align antilipschitz_with.edist_lt_top AntilipschitzWith.edist_lt_top
theorem AntilipschitzWith.edist_ne_top [PseudoEMetricSpace α] [PseudoMetricSpace β] {K : ℝ≥0}
{f : α → β} (h : AntilipschitzWith K f) (x y : α) : edist x y ≠ ⊤ :=
(h.edist_lt_top x y).ne
#align antilipschitz_with.edist_ne_top AntilipschitzWith.edist_ne_top
section Metric
variable [PseudoMetricSpace α] [PseudoMetricSpace β] {K : ℝ≥0} {f : α → β}
theorem antilipschitzWith_iff_le_mul_nndist :
AntilipschitzWith K f ↔ ∀ x y, nndist x y ≤ K * nndist (f x) (f y) := by
simp only [AntilipschitzWith, edist_nndist]
norm_cast
#align antilipschitz_with_iff_le_mul_nndist antilipschitzWith_iff_le_mul_nndist
alias ⟨AntilipschitzWith.le_mul_nndist, AntilipschitzWith.of_le_mul_nndist⟩ :=
antilipschitzWith_iff_le_mul_nndist
#align antilipschitz_with.le_mul_nndist AntilipschitzWith.le_mul_nndist
#align antilipschitz_with.of_le_mul_nndist AntilipschitzWith.of_le_mul_nndist
theorem antilipschitzWith_iff_le_mul_dist :
AntilipschitzWith K f ↔ ∀ x y, dist x y ≤ K * dist (f x) (f y) := by
simp only [antilipschitzWith_iff_le_mul_nndist, dist_nndist]
norm_cast
#align antilipschitz_with_iff_le_mul_dist antilipschitzWith_iff_le_mul_dist
alias ⟨AntilipschitzWith.le_mul_dist, AntilipschitzWith.of_le_mul_dist⟩ :=
antilipschitzWith_iff_le_mul_dist
#align antilipschitz_with.le_mul_dist AntilipschitzWith.le_mul_dist
#align antilipschitz_with.of_le_mul_dist AntilipschitzWith.of_le_mul_dist
namespace AntilipschitzWith
| Mathlib/Topology/MetricSpace/Antilipschitz.lean | 77 | 79 | theorem mul_le_nndist (hf : AntilipschitzWith K f) (x y : α) :
K⁻¹ * nndist x y ≤ nndist (f x) (f y) := by |
simpa only [div_eq_inv_mul] using NNReal.div_le_of_le_mul' (hf.le_mul_nndist x y)
|
/-
Copyright (c) 2020 Scott Morrison. All rights reserved.
Released under Apache 2.0 license as described in the file LICENSE.
Authors: Scott Morrison
-/
import Mathlib.RepresentationTheory.Action.Limits
import Mathlib.RepresentationTheory.Action.Concrete
import Mathlib.CategoryTheory.Monoidal.FunctorCategory
import Mathlib.CategoryTheory.Monoidal.Transport
import Mathlib.CategoryTheory.Monoidal.Rigid.OfEquivalence
import Mathlib.CategoryTheory.Monoidal.Rigid.FunctorCategory
import Mathlib.CategoryTheory.Monoidal.Linear
import Mathlib.CategoryTheory.Monoidal.Braided.Basic
import Mathlib.CategoryTheory.Monoidal.Types.Basic
/-!
# Induced monoidal structure on `Action V G`
We show:
* When `V` is monoidal, braided, or symmetric, so is `Action V G`.
-/
universe u v
open CategoryTheory Limits
variable {V : Type (u + 1)} [LargeCategory V] {G : MonCat.{u}}
namespace Action
section Monoidal
open MonoidalCategory
variable [MonoidalCategory V]
instance instMonoidalCategory : MonoidalCategory (Action V G) :=
Monoidal.transport (Action.functorCategoryEquivalence _ _).symm
@[simp]
theorem tensorUnit_v : (𝟙_ (Action V G)).V = 𝟙_ V :=
rfl
set_option linter.uppercaseLean3 false in
#align Action.tensor_unit_V Action.tensorUnit_v
-- Porting note: removed @[simp] as the simpNF linter complains
theorem tensorUnit_rho {g : G} : (𝟙_ (Action V G)).ρ g = 𝟙 (𝟙_ V) :=
rfl
set_option linter.uppercaseLean3 false in
#align Action.tensor_unit_rho Action.tensorUnit_rho
@[simp]
theorem tensor_v {X Y : Action V G} : (X ⊗ Y).V = X.V ⊗ Y.V :=
rfl
set_option linter.uppercaseLean3 false in
#align Action.tensor_V Action.tensor_v
-- Porting note: removed @[simp] as the simpNF linter complains
theorem tensor_rho {X Y : Action V G} {g : G} : (X ⊗ Y).ρ g = X.ρ g ⊗ Y.ρ g :=
rfl
set_option linter.uppercaseLean3 false in
#align Action.tensor_rho Action.tensor_rho
@[simp]
theorem tensor_hom {W X Y Z : Action V G} (f : W ⟶ X) (g : Y ⟶ Z) : (f ⊗ g).hom = f.hom ⊗ g.hom :=
rfl
set_option linter.uppercaseLean3 false in
#align Action.tensor_hom Action.tensor_hom
@[simp]
theorem whiskerLeft_hom (X : Action V G) {Y Z : Action V G} (f : Y ⟶ Z) :
(X ◁ f).hom = X.V ◁ f.hom :=
rfl
@[simp]
theorem whiskerRight_hom {X Y : Action V G} (f : X ⟶ Y) (Z : Action V G) :
(f ▷ Z).hom = f.hom ▷ Z.V :=
rfl
-- Porting note: removed @[simp] as the simpNF linter complains
theorem associator_hom_hom {X Y Z : Action V G} :
Hom.hom (α_ X Y Z).hom = (α_ X.V Y.V Z.V).hom := by
dsimp
simp
set_option linter.uppercaseLean3 false in
#align Action.associator_hom_hom Action.associator_hom_hom
-- Porting note: removed @[simp] as the simpNF linter complains
theorem associator_inv_hom {X Y Z : Action V G} :
Hom.hom (α_ X Y Z).inv = (α_ X.V Y.V Z.V).inv := by
dsimp
simp
set_option linter.uppercaseLean3 false in
#align Action.associator_inv_hom Action.associator_inv_hom
-- Porting note: removed @[simp] as the simpNF linter complains
| Mathlib/RepresentationTheory/Action/Monoidal.lean | 98 | 100 | theorem leftUnitor_hom_hom {X : Action V G} : Hom.hom (λ_ X).hom = (λ_ X.V).hom := by |
dsimp
simp
|
/-
Copyright (c) 2022 Aaron Anderson. All rights reserved.
Released under Apache 2.0 license as described in the file LICENSE.
Authors: Aaron Anderson
-/
import Mathlib.Data.Fintype.Basic
import Mathlib.ModelTheory.Substructures
#align_import model_theory.elementary_maps from "leanprover-community/mathlib"@"d11893b411025250c8e61ff2f12ccbd7ee35ab15"
/-!
# Elementary Maps Between First-Order Structures
## Main Definitions
* A `FirstOrder.Language.ElementaryEmbedding` is an embedding that commutes with the
realizations of formulas.
* The `FirstOrder.Language.elementaryDiagram` of a structure is the set of all sentences with
parameters that the structure satisfies.
* `FirstOrder.Language.ElementaryEmbedding.ofModelsElementaryDiagram` is the canonical
elementary embedding of any structure into a model of its elementary diagram.
## Main Results
* The Tarski-Vaught Test for embeddings: `FirstOrder.Language.Embedding.isElementary_of_exists`
gives a simple criterion for an embedding to be elementary.
-/
open FirstOrder
namespace FirstOrder
namespace Language
open Structure
variable (L : Language) (M : Type*) (N : Type*) {P : Type*} {Q : Type*}
variable [L.Structure M] [L.Structure N] [L.Structure P] [L.Structure Q]
/-- An elementary embedding of first-order structures is an embedding that commutes with the
realizations of formulas. -/
structure ElementaryEmbedding where
toFun : M → N
-- Porting note:
-- The autoparam here used to be `obviously`. We would like to replace it with `aesop`
-- but that isn't currently sufficient.
-- See https://leanprover.zulipchat.com/#narrow/stream/287929-mathlib4/topic/Aesop.20and.20cases
-- If that can be improved, we should change this to `by aesop` and remove the proofs below.
map_formula' :
∀ ⦃n⦄ (φ : L.Formula (Fin n)) (x : Fin n → M), φ.Realize (toFun ∘ x) ↔ φ.Realize x := by
intros; trivial
#align first_order.language.elementary_embedding FirstOrder.Language.ElementaryEmbedding
#align first_order.language.elementary_embedding.to_fun FirstOrder.Language.ElementaryEmbedding.toFun
#align first_order.language.elementary_embedding.map_formula' FirstOrder.Language.ElementaryEmbedding.map_formula'
@[inherit_doc FirstOrder.Language.ElementaryEmbedding]
scoped[FirstOrder] notation:25 A " ↪ₑ[" L "] " B => FirstOrder.Language.ElementaryEmbedding L A B
variable {L} {M} {N}
namespace ElementaryEmbedding
attribute [coe] toFun
instance instFunLike : FunLike (M ↪ₑ[L] N) M N where
coe f := f.toFun
coe_injective' f g h := by
cases f
cases g
simp only [ElementaryEmbedding.mk.injEq]
ext x
exact Function.funext_iff.1 h x
#align first_order.language.elementary_embedding.fun_like FirstOrder.Language.ElementaryEmbedding.instFunLike
instance : CoeFun (M ↪ₑ[L] N) fun _ => M → N :=
DFunLike.hasCoeToFun
@[simp]
theorem map_boundedFormula (f : M ↪ₑ[L] N) {α : Type*} {n : ℕ} (φ : L.BoundedFormula α n)
(v : α → M) (xs : Fin n → M) : φ.Realize (f ∘ v) (f ∘ xs) ↔ φ.Realize v xs := by
classical
rw [← BoundedFormula.realize_restrictFreeVar Set.Subset.rfl, Set.inclusion_eq_id, iff_eq_eq]
have h :=
f.map_formula' ((φ.restrictFreeVar id).toFormula.relabel (Fintype.equivFin _))
(Sum.elim (v ∘ (↑)) xs ∘ (Fintype.equivFin _).symm)
simp only [Formula.realize_relabel, BoundedFormula.realize_toFormula, iff_eq_eq] at h
rw [← Function.comp.assoc _ _ (Fintype.equivFin _).symm,
Function.comp.assoc _ (Fintype.equivFin _).symm (Fintype.equivFin _),
_root_.Equiv.symm_comp_self, Function.comp_id, Function.comp.assoc, Sum.elim_comp_inl,
Function.comp.assoc _ _ Sum.inr, Sum.elim_comp_inr, ← Function.comp.assoc] at h
refine h.trans ?_
erw [Function.comp.assoc _ _ (Fintype.equivFin _), _root_.Equiv.symm_comp_self,
Function.comp_id, Sum.elim_comp_inl, Sum.elim_comp_inr (v ∘ Subtype.val) xs,
← Set.inclusion_eq_id (s := (BoundedFormula.freeVarFinset φ : Set α)) Set.Subset.rfl,
BoundedFormula.realize_restrictFreeVar Set.Subset.rfl]
#align first_order.language.elementary_embedding.map_bounded_formula FirstOrder.Language.ElementaryEmbedding.map_boundedFormula
@[simp]
| Mathlib/ModelTheory/ElementaryMaps.lean | 98 | 100 | theorem map_formula (f : M ↪ₑ[L] N) {α : Type*} (φ : L.Formula α) (x : α → M) :
φ.Realize (f ∘ x) ↔ φ.Realize x := by |
rw [Formula.Realize, Formula.Realize, ← f.map_boundedFormula, Unique.eq_default (f ∘ default)]
|
/-
Copyright (c) 2020 Anne Baanen. All rights reserved.
Released under Apache 2.0 license as described in the file LICENSE.
Authors: Anne Baanen, Devon Tuma
-/
import Mathlib.Algebra.GroupWithZero.NonZeroDivisors
import Mathlib.Algebra.Polynomial.AlgebraMap
import Mathlib.RingTheory.Coprime.Basic
import Mathlib.Tactic.AdaptationNote
#align_import ring_theory.polynomial.scale_roots from "leanprover-community/mathlib"@"40ac1b258344e0c2b4568dc37bfad937ec35a727"
/-!
# Scaling the roots of a polynomial
This file defines `scaleRoots p s` for a polynomial `p` in one variable and a ring element `s` to
be the polynomial with root `r * s` for each root `r` of `p` and proves some basic results about it.
-/
variable {R S A K : Type*}
namespace Polynomial
open Polynomial
section Semiring
variable [Semiring R] [Semiring S]
/-- `scaleRoots p s` is a polynomial with root `r * s` for each root `r` of `p`. -/
noncomputable def scaleRoots (p : R[X]) (s : R) : R[X] :=
∑ i ∈ p.support, monomial i (p.coeff i * s ^ (p.natDegree - i))
#align polynomial.scale_roots Polynomial.scaleRoots
@[simp]
theorem coeff_scaleRoots (p : R[X]) (s : R) (i : ℕ) :
(scaleRoots p s).coeff i = coeff p i * s ^ (p.natDegree - i) := by
simp (config := { contextual := true }) [scaleRoots, coeff_monomial]
#align polynomial.coeff_scale_roots Polynomial.coeff_scaleRoots
theorem coeff_scaleRoots_natDegree (p : R[X]) (s : R) :
(scaleRoots p s).coeff p.natDegree = p.leadingCoeff := by
rw [leadingCoeff, coeff_scaleRoots, tsub_self, pow_zero, mul_one]
#align polynomial.coeff_scale_roots_nat_degree Polynomial.coeff_scaleRoots_natDegree
@[simp]
theorem zero_scaleRoots (s : R) : scaleRoots 0 s = 0 := by
ext
simp
#align polynomial.zero_scale_roots Polynomial.zero_scaleRoots
theorem scaleRoots_ne_zero {p : R[X]} (hp : p ≠ 0) (s : R) : scaleRoots p s ≠ 0 := by
intro h
have : p.coeff p.natDegree ≠ 0 := mt leadingCoeff_eq_zero.mp hp
have : (scaleRoots p s).coeff p.natDegree = 0 :=
congr_fun (congr_arg (coeff : R[X] → ℕ → R) h) p.natDegree
rw [coeff_scaleRoots_natDegree] at this
contradiction
#align polynomial.scale_roots_ne_zero Polynomial.scaleRoots_ne_zero
theorem support_scaleRoots_le (p : R[X]) (s : R) : (scaleRoots p s).support ≤ p.support := by
intro
simpa using left_ne_zero_of_mul
#align polynomial.support_scale_roots_le Polynomial.support_scaleRoots_le
theorem support_scaleRoots_eq (p : R[X]) {s : R} (hs : s ∈ nonZeroDivisors R) :
(scaleRoots p s).support = p.support :=
le_antisymm (support_scaleRoots_le p s)
(by intro i
simp only [coeff_scaleRoots, Polynomial.mem_support_iff]
intro p_ne_zero ps_zero
have := pow_mem hs (p.natDegree - i) _ ps_zero
contradiction)
#align polynomial.support_scale_roots_eq Polynomial.support_scaleRoots_eq
@[simp]
theorem degree_scaleRoots (p : R[X]) {s : R} : degree (scaleRoots p s) = degree p := by
haveI := Classical.propDecidable
by_cases hp : p = 0
· rw [hp, zero_scaleRoots]
refine le_antisymm (Finset.sup_mono (support_scaleRoots_le p s)) (degree_le_degree ?_)
rw [coeff_scaleRoots_natDegree]
intro h
have := leadingCoeff_eq_zero.mp h
contradiction
#align polynomial.degree_scale_roots Polynomial.degree_scaleRoots
@[simp]
theorem natDegree_scaleRoots (p : R[X]) (s : R) : natDegree (scaleRoots p s) = natDegree p := by
simp only [natDegree, degree_scaleRoots]
#align polynomial.nat_degree_scale_roots Polynomial.natDegree_scaleRoots
theorem monic_scaleRoots_iff {p : R[X]} (s : R) : Monic (scaleRoots p s) ↔ Monic p := by
simp only [Monic, leadingCoeff, natDegree_scaleRoots, coeff_scaleRoots_natDegree]
#align polynomial.monic_scale_roots_iff Polynomial.monic_scaleRoots_iff
| Mathlib/RingTheory/Polynomial/ScaleRoots.lean | 98 | 101 | theorem map_scaleRoots (p : R[X]) (x : R) (f : R →+* S) (h : f p.leadingCoeff ≠ 0) :
(p.scaleRoots x).map f = (p.map f).scaleRoots (f x) := by |
ext
simp [Polynomial.natDegree_map_of_leadingCoeff_ne_zero _ h]
|
/-
Copyright (c) 2020 Johan Commelin. All rights reserved.
Released under Apache 2.0 license as described in the file LICENSE.
Authors: Johan Commelin
-/
import Mathlib.RingTheory.WittVector.Frobenius
import Mathlib.RingTheory.WittVector.Verschiebung
import Mathlib.RingTheory.WittVector.MulP
#align_import ring_theory.witt_vector.identities from "leanprover-community/mathlib"@"0798037604b2d91748f9b43925fb7570a5f3256c"
/-!
## Identities between operations on the ring of Witt vectors
In this file we derive common identities between the Frobenius and Verschiebung operators.
## Main declarations
* `frobenius_verschiebung`: the composition of Frobenius and Verschiebung is multiplication by `p`
* `verschiebung_mul_frobenius`: the “projection formula”: `V(x * F y) = V x * y`
* `iterate_verschiebung_mul_coeff`: an identity from [Haze09] 6.2
## References
* [Hazewinkel, *Witt Vectors*][Haze09]
* [Commelin and Lewis, *Formalizing the Ring of Witt Vectors*][CL21]
-/
namespace WittVector
variable {p : ℕ} {R : Type*} [hp : Fact p.Prime] [CommRing R]
-- type as `\bbW`
local notation "𝕎" => WittVector p
noncomputable section
-- Porting note: `ghost_calc` failure: `simp only []` and the manual instances had to be added.
/-- The composition of Frobenius and Verschiebung is multiplication by `p`. -/
theorem frobenius_verschiebung (x : 𝕎 R) : frobenius (verschiebung x) = x * p := by
have : IsPoly p fun {R} [CommRing R] x ↦ frobenius (verschiebung x) :=
IsPoly.comp (hg := frobenius_isPoly p) (hf := verschiebung_isPoly)
have : IsPoly p fun {R} [CommRing R] x ↦ x * p := mulN_isPoly p p
ghost_calc x
ghost_simp [mul_comm]
#align witt_vector.frobenius_verschiebung WittVector.frobenius_verschiebung
/-- Verschiebung is the same as multiplication by `p` on the ring of Witt vectors of `ZMod p`. -/
theorem verschiebung_zmod (x : 𝕎 (ZMod p)) : verschiebung x = x * p := by
rw [← frobenius_verschiebung, frobenius_zmodp]
#align witt_vector.verschiebung_zmod WittVector.verschiebung_zmod
variable (p R)
| Mathlib/RingTheory/WittVector/Identities.lean | 57 | 61 | theorem coeff_p_pow [CharP R p] (i : ℕ) : ((p : 𝕎 R) ^ i).coeff i = 1 := by |
induction' i with i h
· simp only [Nat.zero_eq, one_coeff_zero, Ne, pow_zero]
· rw [pow_succ, ← frobenius_verschiebung, coeff_frobenius_charP,
verschiebung_coeff_succ, h, one_pow]
|
/-
Copyright (c) 2020 Anne Baanen. All rights reserved.
Released under Apache 2.0 license as described in the file LICENSE.
Authors: Anne Baanen, Filippo A. E. Nuccio
-/
import Mathlib.RingTheory.IntegralClosure
import Mathlib.RingTheory.FractionalIdeal.Basic
#align_import ring_theory.fractional_ideal from "leanprover-community/mathlib"@"ed90a7d327c3a5caf65a6faf7e8a0d63c4605df7"
/-!
# More operations on fractional ideals
## Main definitions
* `map` is the pushforward of a fractional ideal along an algebra morphism
Let `K` be the localization of `R` at `R⁰ = R \ {0}` (i.e. the field of fractions).
* `FractionalIdeal R⁰ K` is the type of fractional ideals in the field of fractions
* `Div (FractionalIdeal R⁰ K)` instance:
the ideal quotient `I / J` (typically written $I : J$, but a `:` operator cannot be defined)
## Main statement
* `isNoetherian` states that every fractional ideal of a noetherian integral domain is noetherian
## References
* https://en.wikipedia.org/wiki/Fractional_ideal
## Tags
fractional ideal, fractional ideals, invertible ideal
-/
open IsLocalization Pointwise nonZeroDivisors
namespace FractionalIdeal
open Set Submodule
variable {R : Type*} [CommRing R] {S : Submonoid R} {P : Type*} [CommRing P]
variable [Algebra R P] [loc : IsLocalization S P]
section
variable {P' : Type*} [CommRing P'] [Algebra R P'] [loc' : IsLocalization S P']
variable {P'' : Type*} [CommRing P''] [Algebra R P''] [loc'' : IsLocalization S P'']
theorem _root_.IsFractional.map (g : P →ₐ[R] P') {I : Submodule R P} :
IsFractional S I → IsFractional S (Submodule.map g.toLinearMap I)
| ⟨a, a_nonzero, hI⟩ =>
⟨a, a_nonzero, fun b hb => by
obtain ⟨b', b'_mem, hb'⟩ := Submodule.mem_map.mp hb
rw [AlgHom.toLinearMap_apply] at hb'
obtain ⟨x, hx⟩ := hI b' b'_mem
use x
rw [← g.commutes, hx, g.map_smul, hb']⟩
#align is_fractional.map IsFractional.map
/-- `I.map g` is the pushforward of the fractional ideal `I` along the algebra morphism `g` -/
def map (g : P →ₐ[R] P') : FractionalIdeal S P → FractionalIdeal S P' := fun I =>
⟨Submodule.map g.toLinearMap I, I.isFractional.map g⟩
#align fractional_ideal.map FractionalIdeal.map
@[simp, norm_cast]
theorem coe_map (g : P →ₐ[R] P') (I : FractionalIdeal S P) :
↑(map g I) = Submodule.map g.toLinearMap I :=
rfl
#align fractional_ideal.coe_map FractionalIdeal.coe_map
@[simp]
theorem mem_map {I : FractionalIdeal S P} {g : P →ₐ[R] P'} {y : P'} :
y ∈ I.map g ↔ ∃ x, x ∈ I ∧ g x = y :=
Submodule.mem_map
#align fractional_ideal.mem_map FractionalIdeal.mem_map
variable (I J : FractionalIdeal S P) (g : P →ₐ[R] P')
@[simp]
theorem map_id : I.map (AlgHom.id _ _) = I :=
coeToSubmodule_injective (Submodule.map_id (I : Submodule R P))
#align fractional_ideal.map_id FractionalIdeal.map_id
@[simp]
theorem map_comp (g' : P' →ₐ[R] P'') : I.map (g'.comp g) = (I.map g).map g' :=
coeToSubmodule_injective (Submodule.map_comp g.toLinearMap g'.toLinearMap I)
#align fractional_ideal.map_comp FractionalIdeal.map_comp
@[simp, norm_cast]
theorem map_coeIdeal (I : Ideal R) : (I : FractionalIdeal S P).map g = I := by
ext x
simp only [mem_coeIdeal]
constructor
· rintro ⟨_, ⟨y, hy, rfl⟩, rfl⟩
exact ⟨y, hy, (g.commutes y).symm⟩
· rintro ⟨y, hy, rfl⟩
exact ⟨_, ⟨y, hy, rfl⟩, g.commutes y⟩
#align fractional_ideal.map_coe_ideal FractionalIdeal.map_coeIdeal
@[simp]
theorem map_one : (1 : FractionalIdeal S P).map g = 1 :=
map_coeIdeal g ⊤
#align fractional_ideal.map_one FractionalIdeal.map_one
@[simp]
theorem map_zero : (0 : FractionalIdeal S P).map g = 0 :=
map_coeIdeal g 0
#align fractional_ideal.map_zero FractionalIdeal.map_zero
@[simp]
theorem map_add : (I + J).map g = I.map g + J.map g :=
coeToSubmodule_injective (Submodule.map_sup _ _ _)
#align fractional_ideal.map_add FractionalIdeal.map_add
@[simp]
theorem map_mul : (I * J).map g = I.map g * J.map g := by
simp only [mul_def]
exact coeToSubmodule_injective (Submodule.map_mul _ _ _)
#align fractional_ideal.map_mul FractionalIdeal.map_mul
@[simp]
theorem map_map_symm (g : P ≃ₐ[R] P') : (I.map (g : P →ₐ[R] P')).map (g.symm : P' →ₐ[R] P) = I := by
rw [← map_comp, g.symm_comp, map_id]
#align fractional_ideal.map_map_symm FractionalIdeal.map_map_symm
@[simp]
| Mathlib/RingTheory/FractionalIdeal/Operations.lean | 128 | 130 | theorem map_symm_map (I : FractionalIdeal S P') (g : P ≃ₐ[R] P') :
(I.map (g.symm : P' →ₐ[R] P)).map (g : P →ₐ[R] P') = I := by |
rw [← map_comp, g.comp_symm, map_id]
|
/-
Copyright (c) 2017 Johannes Hölzl. All rights reserved.
Released under Apache 2.0 license as described in the file LICENSE.
Authors: Johannes Hölzl, Mario Carneiro, Kevin Buzzard, Yury Kudryashov, Eric Wieser
-/
import Mathlib.GroupTheory.GroupAction.BigOperators
import Mathlib.Logic.Equiv.Fin
import Mathlib.Algebra.BigOperators.Pi
import Mathlib.Algebra.Module.Prod
import Mathlib.Algebra.Module.Submodule.Ker
#align_import linear_algebra.pi from "leanprover-community/mathlib"@"dc6c365e751e34d100e80fe6e314c3c3e0fd2988"
/-!
# Pi types of modules
This file defines constructors for linear maps whose domains or codomains are pi types.
It contains theorems relating these to each other, as well as to `LinearMap.ker`.
## Main definitions
- pi types in the codomain:
- `LinearMap.pi`
- `LinearMap.single`
- pi types in the domain:
- `LinearMap.proj`
- `LinearMap.diag`
-/
universe u v w x y z u' v' w' x' y'
variable {R : Type u} {K : Type u'} {M : Type v} {V : Type v'} {M₂ : Type w} {V₂ : Type w'}
variable {M₃ : Type y} {V₃ : Type y'} {M₄ : Type z} {ι : Type x} {ι' : Type x'}
open Function Submodule
namespace LinearMap
universe i
variable [Semiring R] [AddCommMonoid M₂] [Module R M₂] [AddCommMonoid M₃] [Module R M₃]
{φ : ι → Type i} [(i : ι) → AddCommMonoid (φ i)] [(i : ι) → Module R (φ i)]
/-- `pi` construction for linear functions. From a family of linear functions it produces a linear
function into a family of modules. -/
def pi (f : (i : ι) → M₂ →ₗ[R] φ i) : M₂ →ₗ[R] (i : ι) → φ i :=
{ Pi.addHom fun i => (f i).toAddHom with
toFun := fun c i => f i c
map_smul' := fun _ _ => funext fun i => (f i).map_smul _ _ }
#align linear_map.pi LinearMap.pi
@[simp]
theorem pi_apply (f : (i : ι) → M₂ →ₗ[R] φ i) (c : M₂) (i : ι) : pi f c i = f i c :=
rfl
#align linear_map.pi_apply LinearMap.pi_apply
theorem ker_pi (f : (i : ι) → M₂ →ₗ[R] φ i) : ker (pi f) = ⨅ i : ι, ker (f i) := by
ext c; simp [funext_iff]
#align linear_map.ker_pi LinearMap.ker_pi
| Mathlib/LinearAlgebra/Pi.lean | 64 | 66 | theorem pi_eq_zero (f : (i : ι) → M₂ →ₗ[R] φ i) : pi f = 0 ↔ ∀ i, f i = 0 := by |
simp only [LinearMap.ext_iff, pi_apply, funext_iff];
exact ⟨fun h a b => h b a, fun h a b => h b a⟩
|
/-
Copyright (c) 2023 Yury Kudryashov. All rights reserved.
Released under Apache 2.0 license as described in the file LICENSE.
Authors: Yury Kudryashov, Joseph Myers
-/
import Mathlib.Analysis.InnerProductSpace.Orthogonal
import Mathlib.Analysis.Normed.Group.AddTorsor
#align_import geometry.euclidean.basic from "leanprover-community/mathlib"@"2de9c37fa71dde2f1c6feff19876dd6a7b1519f0"
/-!
# Perpendicular bisector of a segment
We define `AffineSubspace.perpBisector p₁ p₂` to be the perpendicular bisector of the segment
`[p₁, p₂]`, as a bundled affine subspace. We also prove that a point belongs to the perpendicular
bisector if and only if it is equidistant from `p₁` and `p₂`, as well as a few linear equations that
define this subspace.
## Keywords
euclidean geometry, perpendicular, perpendicular bisector, line segment bisector, equidistant
-/
open Set
open scoped RealInnerProductSpace
variable {V P : Type*} [NormedAddCommGroup V] [InnerProductSpace ℝ V] [MetricSpace P]
variable [NormedAddTorsor V P]
noncomputable section
namespace AffineSubspace
variable {c c₁ c₂ p₁ p₂ : P}
/-- Perpendicular bisector of a segment in a Euclidean affine space. -/
def perpBisector (p₁ p₂ : P) : AffineSubspace ℝ P :=
.comap ((AffineEquiv.vaddConst ℝ (midpoint ℝ p₁ p₂)).symm : P →ᵃ[ℝ] V) <|
(LinearMap.ker (innerₛₗ ℝ (p₂ -ᵥ p₁))).toAffineSubspace
/-- A point `c` belongs the perpendicular bisector of `[p₁, p₂] iff `p₂ -ᵥ p₁` is orthogonal to
`c -ᵥ midpoint ℝ p₁ p₂`. -/
theorem mem_perpBisector_iff_inner_eq_zero' :
c ∈ perpBisector p₁ p₂ ↔ ⟪p₂ -ᵥ p₁, c -ᵥ midpoint ℝ p₁ p₂⟫ = 0 :=
Iff.rfl
/-- A point `c` belongs the perpendicular bisector of `[p₁, p₂] iff `c -ᵥ midpoint ℝ p₁ p₂` is
orthogonal to `p₂ -ᵥ p₁`. -/
theorem mem_perpBisector_iff_inner_eq_zero :
c ∈ perpBisector p₁ p₂ ↔ ⟪c -ᵥ midpoint ℝ p₁ p₂, p₂ -ᵥ p₁⟫ = 0 :=
inner_eq_zero_symm
theorem mem_perpBisector_iff_inner_pointReflection_vsub_eq_zero :
c ∈ perpBisector p₁ p₂ ↔ ⟪Equiv.pointReflection c p₁ -ᵥ p₂, p₂ -ᵥ p₁⟫ = 0 := by
rw [mem_perpBisector_iff_inner_eq_zero, Equiv.pointReflection_apply,
vsub_midpoint, invOf_eq_inv, ← smul_add, real_inner_smul_left, vadd_vsub_assoc]
simp
theorem mem_perpBisector_pointReflection_iff_inner_eq_zero :
c ∈ perpBisector p₁ (Equiv.pointReflection p₂ p₁) ↔ ⟪c -ᵥ p₂, p₁ -ᵥ p₂⟫ = 0 := by
rw [mem_perpBisector_iff_inner_eq_zero, midpoint_pointReflection_right,
Equiv.pointReflection_apply, vadd_vsub_assoc, inner_add_right, add_self_eq_zero,
← neg_eq_zero, ← inner_neg_right, neg_vsub_eq_vsub_rev]
theorem midpoint_mem_perpBisector (p₁ p₂ : P) :
midpoint ℝ p₁ p₂ ∈ perpBisector p₁ p₂ := by
simp [mem_perpBisector_iff_inner_eq_zero]
theorem perpBisector_nonempty : (perpBisector p₁ p₂ : Set P).Nonempty :=
⟨_, midpoint_mem_perpBisector _ _⟩
@[simp]
theorem direction_perpBisector (p₁ p₂ : P) :
(perpBisector p₁ p₂).direction = (ℝ ∙ (p₂ -ᵥ p₁))ᗮ := by
erw [perpBisector, comap_symm, map_direction, Submodule.map_id,
Submodule.toAffineSubspace_direction]
ext x
exact Submodule.mem_orthogonal_singleton_iff_inner_right.symm
theorem mem_perpBisector_iff_inner_eq_inner :
c ∈ perpBisector p₁ p₂ ↔ ⟪c -ᵥ p₁, p₂ -ᵥ p₁⟫ = ⟪c -ᵥ p₂, p₁ -ᵥ p₂⟫ := by
rw [Iff.comm, mem_perpBisector_iff_inner_eq_zero, ← add_neg_eq_zero, ← inner_neg_right,
neg_vsub_eq_vsub_rev, ← inner_add_left, vsub_midpoint, invOf_eq_inv, ← smul_add,
real_inner_smul_left]; simp
theorem mem_perpBisector_iff_inner_eq :
c ∈ perpBisector p₁ p₂ ↔ ⟪c -ᵥ p₁, p₂ -ᵥ p₁⟫ = (dist p₁ p₂) ^ 2 / 2 := by
rw [mem_perpBisector_iff_inner_eq_zero, ← vsub_sub_vsub_cancel_right _ _ p₁, inner_sub_left,
sub_eq_zero, midpoint_vsub_left, invOf_eq_inv, real_inner_smul_left, real_inner_self_eq_norm_sq,
dist_eq_norm_vsub' V, div_eq_inv_mul]
| Mathlib/Geometry/Euclidean/PerpBisector.lean | 92 | 95 | theorem mem_perpBisector_iff_dist_eq : c ∈ perpBisector p₁ p₂ ↔ dist c p₁ = dist c p₂ := by |
rw [dist_eq_norm_vsub V, dist_eq_norm_vsub V, ← real_inner_add_sub_eq_zero_iff,
vsub_sub_vsub_cancel_left, inner_add_left, add_eq_zero_iff_eq_neg, ← inner_neg_right,
neg_vsub_eq_vsub_rev, mem_perpBisector_iff_inner_eq_inner]
|
/-
Copyright (c) 2017 Mario Carneiro. All rights reserved.
Released under Apache 2.0 license as described in the file LICENSE.
Authors: Mario Carneiro
-/
import Mathlib.Algebra.Order.Ring.Defs
import Mathlib.Algebra.Group.Int
import Mathlib.Data.Nat.Dist
import Mathlib.Data.Ordmap.Ordnode
import Mathlib.Tactic.Abel
import Mathlib.Tactic.Linarith
#align_import data.ordmap.ordset from "leanprover-community/mathlib"@"47b51515e69f59bca5cf34ef456e6000fe205a69"
/-!
# Verification of the `Ordnode α` datatype
This file proves the correctness of the operations in `Data.Ordmap.Ordnode`.
The public facing version is the type `Ordset α`, which is a wrapper around
`Ordnode α` which includes the correctness invariant of the type, and it exposes
parallel operations like `insert` as functions on `Ordset` that do the same
thing but bundle the correctness proofs. The advantage is that it is possible
to, for example, prove that the result of `find` on `insert` will actually find
the element, while `Ordnode` cannot guarantee this if the input tree did not
satisfy the type invariants.
## Main definitions
* `Ordset α`: A well formed set of values of type `α`
## Implementation notes
The majority of this file is actually in the `Ordnode` namespace, because we first
have to prove the correctness of all the operations (and defining what correctness
means here is actually somewhat subtle). So all the actual `Ordset` operations are
at the very end, once we have all the theorems.
An `Ordnode α` is an inductive type which describes a tree which stores the `size` at
internal nodes. The correctness invariant of an `Ordnode α` is:
* `Ordnode.Sized t`: All internal `size` fields must match the actual measured
size of the tree. (This is not hard to satisfy.)
* `Ordnode.Balanced t`: Unless the tree has the form `()` or `((a) b)` or `(a (b))`
(that is, nil or a single singleton subtree), the two subtrees must satisfy
`size l ≤ δ * size r` and `size r ≤ δ * size l`, where `δ := 3` is a global
parameter of the data structure (and this property must hold recursively at subtrees).
This is why we say this is a "size balanced tree" data structure.
* `Ordnode.Bounded lo hi t`: The members of the tree must be in strictly increasing order,
meaning that if `a` is in the left subtree and `b` is the root, then `a ≤ b` and
`¬ (b ≤ a)`. We enforce this using `Ordnode.Bounded` which includes also a global
upper and lower bound.
Because the `Ordnode` file was ported from Haskell, the correctness invariants of some
of the functions have not been spelled out, and some theorems like
`Ordnode.Valid'.balanceL_aux` show very intricate assumptions on the sizes,
which may need to be revised if it turns out some operations violate these assumptions,
because there is a decent amount of slop in the actual data structure invariants, so the
theorem will go through with multiple choices of assumption.
**Note:** This file is incomplete, in the sense that the intent is to have verified
versions and lemmas about all the definitions in `Ordnode.lean`, but at the moment only
a few operations are verified (the hard part should be out of the way, but still).
Contributors are encouraged to pick this up and finish the job, if it appeals to you.
## Tags
ordered map, ordered set, data structure, verified programming
-/
variable {α : Type*}
namespace Ordnode
/-! ### delta and ratio -/
theorem not_le_delta {s} (H : 1 ≤ s) : ¬s ≤ delta * 0 :=
not_le_of_gt H
#align ordnode.not_le_delta Ordnode.not_le_delta
theorem delta_lt_false {a b : ℕ} (h₁ : delta * a < b) (h₂ : delta * b < a) : False :=
not_le_of_lt (lt_trans ((mul_lt_mul_left (by decide)).2 h₁) h₂) <| by
simpa [mul_assoc] using Nat.mul_le_mul_right a (by decide : 1 ≤ delta * delta)
#align ordnode.delta_lt_false Ordnode.delta_lt_false
/-! ### `singleton` -/
/-! ### `size` and `empty` -/
/-- O(n). Computes the actual number of elements in the set, ignoring the cached `size` field. -/
def realSize : Ordnode α → ℕ
| nil => 0
| node _ l _ r => realSize l + realSize r + 1
#align ordnode.real_size Ordnode.realSize
/-! ### `Sized` -/
/-- The `Sized` property asserts that all the `size` fields in nodes match the actual size of the
respective subtrees. -/
def Sized : Ordnode α → Prop
| nil => True
| node s l _ r => s = size l + size r + 1 ∧ Sized l ∧ Sized r
#align ordnode.sized Ordnode.Sized
theorem Sized.node' {l x r} (hl : @Sized α l) (hr : Sized r) : Sized (node' l x r) :=
⟨rfl, hl, hr⟩
#align ordnode.sized.node' Ordnode.Sized.node'
| Mathlib/Data/Ordmap/Ordset.lean | 114 | 115 | theorem Sized.eq_node' {s l x r} (h : @Sized α (node s l x r)) : node s l x r = .node' l x r := by |
rw [h.1]
|
/-
Copyright (c) 2022 Ivan Sadofschi Costa. All rights reserved.
Released under Apache 2.0 license as described in the file LICENSE.
Authors: Ivan Sadofschi Costa
-/
import Mathlib.Topology.Order
import Mathlib.Topology.Sets.Opens
import Mathlib.Topology.ContinuousFunction.Basic
#align_import topology.continuous_function.t0_sierpinski from "leanprover-community/mathlib"@"dc6c365e751e34d100e80fe6e314c3c3e0fd2988"
/-!
# Any T0 space embeds in a product of copies of the Sierpinski space.
We consider `Prop` with the Sierpinski topology. If `X` is a topological space, there is a
continuous map `productOfMemOpens` from `X` to `Opens X → Prop` which is the product of the maps
`X → Prop` given by `x ↦ x ∈ u`.
The map `productOfMemOpens` is always inducing. Whenever `X` is T0, `productOfMemOpens` is
also injective and therefore an embedding.
-/
noncomputable section
namespace TopologicalSpace
theorem eq_induced_by_maps_to_sierpinski (X : Type*) [t : TopologicalSpace X] :
t = ⨅ u : Opens X, sierpinskiSpace.induced (· ∈ u) := by
apply le_antisymm
· rw [le_iInf_iff]
exact fun u => Continuous.le_induced (isOpen_iff_continuous_mem.mp u.2)
· intro u h
rw [← generateFrom_iUnion_isOpen]
apply isOpen_generateFrom_of_mem
simp only [Set.mem_iUnion, Set.mem_setOf_eq, isOpen_induced_iff]
exact ⟨⟨u, h⟩, {True}, isOpen_singleton_true, by simp [Set.preimage]⟩
#align topological_space.eq_induced_by_maps_to_sierpinski TopologicalSpace.eq_induced_by_maps_to_sierpinski
variable (X : Type*) [TopologicalSpace X]
/-- The continuous map from `X` to the product of copies of the Sierpinski space, (one copy for each
open subset `u` of `X`). The `u` coordinate of `productOfMemOpens x` is given by `x ∈ u`.
-/
def productOfMemOpens : C(X, Opens X → Prop) where
toFun x u := x ∈ u
continuous_toFun := continuous_pi_iff.2 fun u => continuous_Prop.2 u.isOpen
#align topological_space.product_of_mem_opens TopologicalSpace.productOfMemOpens
theorem productOfMemOpens_inducing : Inducing (productOfMemOpens X) := by
convert inducing_iInf_to_pi fun (u : Opens X) (x : X) => x ∈ u
apply eq_induced_by_maps_to_sierpinski
#align topological_space.product_of_mem_opens_inducing TopologicalSpace.productOfMemOpens_inducing
| Mathlib/Topology/ContinuousFunction/T0Sierpinski.lean | 55 | 58 | theorem productOfMemOpens_injective [T0Space X] : Function.Injective (productOfMemOpens X) := by |
intro x1 x2 h
apply Inseparable.eq
rw [← Inducing.inseparable_iff (productOfMemOpens_inducing X), h]
|
/-
Copyright (c) 2014 Jeremy Avigad. All rights reserved.
Released under Apache 2.0 license as described in the file LICENSE.
Authors: Jeremy Avigad, Leonardo de Moura, Floris van Doorn, Yury Kudryashov, Neil Strickland
-/
import Mathlib.Algebra.Ring.InjSurj
import Mathlib.Algebra.Group.Units.Hom
import Mathlib.Algebra.Ring.Hom.Defs
#align_import algebra.ring.units from "leanprover-community/mathlib"@"2ed7e4aec72395b6a7c3ac4ac7873a7a43ead17c"
/-!
# Units in semirings and rings
-/
universe u v w x
variable {α : Type u} {β : Type v} {γ : Type w} {R : Type x}
open Function
namespace Units
section HasDistribNeg
variable [Monoid α] [HasDistribNeg α] {a b : α}
/-- Each element of the group of units of a ring has an additive inverse. -/
instance : Neg αˣ :=
⟨fun u => ⟨-↑u, -↑u⁻¹, by simp, by simp⟩⟩
/-- Representing an element of a ring's unit group as an element of the ring commutes with
mapping this element to its additive inverse. -/
@[simp, norm_cast]
protected theorem val_neg (u : αˣ) : (↑(-u) : α) = -u :=
rfl
#align units.coe_neg Units.val_neg
@[simp, norm_cast]
protected theorem coe_neg_one : ((-1 : αˣ) : α) = -1 :=
rfl
#align units.coe_neg_one Units.coe_neg_one
instance : HasDistribNeg αˣ :=
Units.ext.hasDistribNeg _ Units.val_neg Units.val_mul
@[field_simps]
| Mathlib/Algebra/Ring/Units.lean | 50 | 50 | theorem neg_divp (a : α) (u : αˣ) : -(a /ₚ u) = -a /ₚ u := by | simp only [divp, neg_mul]
|
/-
Copyright (c) 2014 Jeremy Avigad. All rights reserved.
Released under Apache 2.0 license as described in the file LICENSE.
Authors: Jeremy Avigad, Leonardo de Moura, Mario Carneiro
-/
import Batteries.Data.Nat.Gcd
import Mathlib.Init.Data.Nat.Notation
import Mathlib.Mathport.Rename
#align_import init.data.nat.gcd from "leanprover-community/lean"@"855e5b74e3a52a40552e8f067169d747d48743fd"
/-!
# Definitions and properties of gcd, lcm, and coprime
-/
open WellFounded
namespace Nat
/-! gcd -/
#align nat.gcd Nat.gcd
#align nat.gcd_zero_left Nat.gcd_zero_left
#align nat.gcd_succ Nat.gcd_succ
#align nat.gcd_one_left Nat.gcd_one_left
#align nat.gcd_self Nat.gcd_self
#align nat.gcd_zero_right Nat.gcd_zero_right
#align nat.gcd_rec Nat.gcd_rec
#align nat.gcd.induction Nat.gcd.induction
#align nat.lcm Nat.lcm
| Mathlib/Init/Data/Nat/GCD.lean | 35 | 36 | theorem gcd_def (x y : ℕ) : gcd x y = if x = 0 then y else gcd (y % x) x := by |
cases x <;> simp [Nat.gcd_succ]
|
/-
Copyright (c) 2019 Kevin Kappelmann. All rights reserved.
Released under Apache 2.0 license as described in the file LICENSE.
Authors: Kevin Kappelmann
-/
import Mathlib.Algebra.ContinuedFractions.Translations
#align_import algebra.continued_fractions.continuants_recurrence from "leanprover-community/mathlib"@"5f11361a98ae4acd77f5c1837686f6f0102cdc25"
/-!
# Recurrence Lemmas for the `continuants` Function of Continued Fractions.
## Summary
Given a generalized continued fraction `g`, for all `n ≥ 1`, we prove that the `continuants`
function indeed satisfies the following recurrences:
- `Aₙ = bₙ * Aₙ₋₁ + aₙ * Aₙ₋₂`, and
- `Bₙ = bₙ * Bₙ₋₁ + aₙ * Bₙ₋₂`.
-/
namespace GeneralizedContinuedFraction
variable {K : Type*} {g : GeneralizedContinuedFraction K} {n : ℕ} [DivisionRing K]
theorem continuantsAux_recurrence {gp ppred pred : Pair K} (nth_s_eq : g.s.get? n = some gp)
(nth_conts_aux_eq : g.continuantsAux n = ppred)
(succ_nth_conts_aux_eq : g.continuantsAux (n + 1) = pred) :
g.continuantsAux (n + 2) = ⟨gp.b * pred.a + gp.a * ppred.a, gp.b * pred.b + gp.a * ppred.b⟩ :=
by simp [*, continuantsAux, nextContinuants, nextDenominator, nextNumerator]
#align generalized_continued_fraction.continuants_aux_recurrence GeneralizedContinuedFraction.continuantsAux_recurrence
| Mathlib/Algebra/ContinuedFractions/ContinuantsRecurrence.lean | 33 | 38 | theorem continuants_recurrenceAux {gp ppred pred : Pair K} (nth_s_eq : g.s.get? n = some gp)
(nth_conts_aux_eq : g.continuantsAux n = ppred)
(succ_nth_conts_aux_eq : g.continuantsAux (n + 1) = pred) :
g.continuants (n + 1) = ⟨gp.b * pred.a + gp.a * ppred.a, gp.b * pred.b + gp.a * ppred.b⟩ := by |
simp [nth_cont_eq_succ_nth_cont_aux,
continuantsAux_recurrence nth_s_eq nth_conts_aux_eq succ_nth_conts_aux_eq]
|
/-
Copyright (c) 2022 Violeta Hernández Palacios. All rights reserved.
Released under Apache 2.0 license as described in the file LICENSE.
Authors: Violeta Hernández Palacios
-/
import Mathlib.SetTheory.Game.Ordinal
import Mathlib.SetTheory.Ordinal.NaturalOps
#align_import set_theory.game.birthday from "leanprover-community/mathlib"@"a347076985674932c0e91da09b9961ed0a79508c"
/-!
# Birthdays of games
The birthday of a game is an ordinal that represents at which "step" the game was constructed. We
define it recursively as the least ordinal larger than the birthdays of its left and right games. We
prove the basic properties about these.
# Main declarations
- `SetTheory.PGame.birthday`: The birthday of a pre-game.
# Todo
- Define the birthdays of `SetTheory.Game`s and `Surreal`s.
- Characterize the birthdays of basic arithmetical operations.
-/
universe u
open Ordinal
namespace SetTheory
open scoped NaturalOps PGame
namespace PGame
/-- The birthday of a pre-game is inductively defined as the least strict upper bound of the
birthdays of its left and right games. It may be thought as the "step" in which a certain game is
constructed. -/
noncomputable def birthday : PGame.{u} → Ordinal.{u}
| ⟨_, _, xL, xR⟩ =>
max (lsub.{u, u} fun i => birthday (xL i)) (lsub.{u, u} fun i => birthday (xR i))
#align pgame.birthday SetTheory.PGame.birthday
theorem birthday_def (x : PGame) :
birthday x =
max (lsub.{u, u} fun i => birthday (x.moveLeft i))
(lsub.{u, u} fun i => birthday (x.moveRight i)) := by
cases x; rw [birthday]; rfl
#align pgame.birthday_def SetTheory.PGame.birthday_def
| Mathlib/SetTheory/Game/Birthday.lean | 54 | 56 | theorem birthday_moveLeft_lt {x : PGame} (i : x.LeftMoves) :
(x.moveLeft i).birthday < x.birthday := by |
cases x; rw [birthday]; exact lt_max_of_lt_left (lt_lsub _ i)
|
/-
Copyright (c) 2022 Yury Kudryashov. All rights reserved.
Released under Apache 2.0 license as described in the file LICENSE.
Authors: Yury Kudryashov
-/
import Mathlib.Analysis.Calculus.FDeriv.Analytic
import Mathlib.Analysis.Asymptotics.SpecificAsymptotics
import Mathlib.Analysis.Complex.CauchyIntegral
#align_import analysis.complex.removable_singularity from "leanprover-community/mathlib"@"f2ce6086713c78a7f880485f7917ea547a215982"
/-!
# Removable singularity theorem
In this file we prove Riemann's removable singularity theorem: if `f : ℂ → E` is complex
differentiable in a punctured neighborhood of a point `c` and is bounded in a punctured neighborhood
of `c` (or, more generally, $f(z) - f(c)=o((z-c)^{-1})$), then it has a limit at `c` and the
function `update f c (limUnder (𝓝[≠] c) f)` is complex differentiable in a neighborhood of `c`.
-/
open TopologicalSpace Metric Set Filter Asymptotics Function
open scoped Topology Filter NNReal Real
universe u
variable {E : Type u} [NormedAddCommGroup E] [NormedSpace ℂ E] [CompleteSpace E]
namespace Complex
/-- **Removable singularity** theorem, weak version. If `f : ℂ → E` is differentiable in a punctured
neighborhood of a point and is continuous at this point, then it is analytic at this point. -/
theorem analyticAt_of_differentiable_on_punctured_nhds_of_continuousAt {f : ℂ → E} {c : ℂ}
(hd : ∀ᶠ z in 𝓝[≠] c, DifferentiableAt ℂ f z) (hc : ContinuousAt f c) : AnalyticAt ℂ f c := by
rcases (nhdsWithin_hasBasis nhds_basis_closedBall _).mem_iff.1 hd with ⟨R, hR0, hRs⟩
lift R to ℝ≥0 using hR0.le
replace hc : ContinuousOn f (closedBall c R) := by
refine fun z hz => ContinuousAt.continuousWithinAt ?_
rcases eq_or_ne z c with (rfl | hne)
exacts [hc, (hRs ⟨hz, hne⟩).continuousAt]
exact (hasFPowerSeriesOnBall_of_differentiable_off_countable (countable_singleton c) hc
(fun z hz => hRs (diff_subset_diff_left ball_subset_closedBall hz)) hR0).analyticAt
#align complex.analytic_at_of_differentiable_on_punctured_nhds_of_continuous_at Complex.analyticAt_of_differentiable_on_punctured_nhds_of_continuousAt
theorem differentiableOn_compl_singleton_and_continuousAt_iff {f : ℂ → E} {s : Set ℂ} {c : ℂ}
(hs : s ∈ 𝓝 c) :
DifferentiableOn ℂ f (s \ {c}) ∧ ContinuousAt f c ↔ DifferentiableOn ℂ f s := by
refine ⟨?_, fun hd => ⟨hd.mono diff_subset, (hd.differentiableAt hs).continuousAt⟩⟩
rintro ⟨hd, hc⟩ x hx
rcases eq_or_ne x c with (rfl | hne)
· refine (analyticAt_of_differentiable_on_punctured_nhds_of_continuousAt
?_ hc).differentiableAt.differentiableWithinAt
refine eventually_nhdsWithin_iff.2 ((eventually_mem_nhds.2 hs).mono fun z hz hzx => ?_)
exact hd.differentiableAt (inter_mem hz (isOpen_ne.mem_nhds hzx))
· simpa only [DifferentiableWithinAt, HasFDerivWithinAt, hne.nhdsWithin_diff_singleton] using
hd x ⟨hx, hne⟩
#align complex.differentiable_on_compl_singleton_and_continuous_at_iff Complex.differentiableOn_compl_singleton_and_continuousAt_iff
theorem differentiableOn_dslope {f : ℂ → E} {s : Set ℂ} {c : ℂ} (hc : s ∈ 𝓝 c) :
DifferentiableOn ℂ (dslope f c) s ↔ DifferentiableOn ℂ f s :=
⟨fun h => h.of_dslope, fun h =>
(differentiableOn_compl_singleton_and_continuousAt_iff hc).mp <|
⟨Iff.mpr (differentiableOn_dslope_of_nmem fun h => h.2 rfl) (h.mono diff_subset),
continuousAt_dslope_same.2 <| h.differentiableAt hc⟩⟩
#align complex.differentiable_on_dslope Complex.differentiableOn_dslope
/-- **Removable singularity** theorem: if `s` is a neighborhood of `c : ℂ`, a function `f : ℂ → E`
is complex differentiable on `s \ {c}`, and $f(z) - f(c)=o((z-c)^{-1})$, then `f` redefined to be
equal to `limUnder (𝓝[≠] c) f` at `c` is complex differentiable on `s`. -/
| Mathlib/Analysis/Complex/RemovableSingularity.lean | 71 | 87 | theorem differentiableOn_update_limUnder_of_isLittleO {f : ℂ → E} {s : Set ℂ} {c : ℂ} (hc : s ∈ 𝓝 c)
(hd : DifferentiableOn ℂ f (s \ {c}))
(ho : (fun z => f z - f c) =o[𝓝[≠] c] fun z => (z - c)⁻¹) :
DifferentiableOn ℂ (update f c (limUnder (𝓝[≠] c) f)) s := by |
set F : ℂ → E := fun z => (z - c) • f z
suffices DifferentiableOn ℂ F (s \ {c}) ∧ ContinuousAt F c by
rw [differentiableOn_compl_singleton_and_continuousAt_iff hc, ← differentiableOn_dslope hc,
dslope_sub_smul] at this
have hc : Tendsto f (𝓝[≠] c) (𝓝 (deriv F c)) :=
continuousAt_update_same.mp (this.continuousOn.continuousAt hc)
rwa [hc.limUnder_eq]
refine ⟨(differentiableOn_id.sub_const _).smul hd, ?_⟩
rw [← continuousWithinAt_compl_self]
have H := ho.tendsto_inv_smul_nhds_zero
have H' : Tendsto (fun z => (z - c) • f c) (𝓝[≠] c) (𝓝 (F c)) :=
(continuousWithinAt_id.tendsto.sub tendsto_const_nhds).smul tendsto_const_nhds
simpa [← smul_add, ContinuousWithinAt] using H.add H'
|
/-
Copyright (c) 2019 Jeremy Avigad. All rights reserved.
Released under Apache 2.0 license as described in the file LICENSE.
Authors: Jeremy Avigad, Yury Kudryashov
-/
import Mathlib.Analysis.Normed.Group.InfiniteSum
import Mathlib.Analysis.Normed.MulAction
import Mathlib.Topology.Algebra.Order.LiminfLimsup
import Mathlib.Topology.PartialHomeomorph
#align_import analysis.asymptotics.asymptotics from "leanprover-community/mathlib"@"f2ce6086713c78a7f880485f7917ea547a215982"
/-!
# Asymptotics
We introduce these relations:
* `IsBigOWith c l f g` : "f is big O of g along l with constant c";
* `f =O[l] g` : "f is big O of g along l";
* `f =o[l] g` : "f is little o of g along l".
Here `l` is any filter on the domain of `f` and `g`, which are assumed to be the same. The codomains
of `f` and `g` do not need to be the same; all that is needed that there is a norm associated with
these types, and it is the norm that is compared asymptotically.
The relation `IsBigOWith c` is introduced to factor out common algebraic arguments in the proofs of
similar properties of `IsBigO` and `IsLittleO`. Usually proofs outside of this file should use
`IsBigO` instead.
Often the ranges of `f` and `g` will be the real numbers, in which case the norm is the absolute
value. In general, we have
`f =O[l] g ↔ (fun x ↦ ‖f x‖) =O[l] (fun x ↦ ‖g x‖)`,
and similarly for `IsLittleO`. But our setup allows us to use the notions e.g. with functions
to the integers, rationals, complex numbers, or any normed vector space without mentioning the
norm explicitly.
If `f` and `g` are functions to a normed field like the reals or complex numbers and `g` is always
nonzero, we have
`f =o[l] g ↔ Tendsto (fun x ↦ f x / (g x)) l (𝓝 0)`.
In fact, the right-to-left direction holds without the hypothesis on `g`, and in the other direction
it suffices to assume that `f` is zero wherever `g` is. (This generalization is useful in defining
the Fréchet derivative.)
-/
open Filter Set
open scoped Classical
open Topology Filter NNReal
namespace Asymptotics
set_option linter.uppercaseLean3 false
variable {α : Type*} {β : Type*} {E : Type*} {F : Type*} {G : Type*} {E' : Type*}
{F' : Type*} {G' : Type*} {E'' : Type*} {F'' : Type*} {G'' : Type*} {E''' : Type*}
{R : Type*} {R' : Type*} {𝕜 : Type*} {𝕜' : Type*}
variable [Norm E] [Norm F] [Norm G]
variable [SeminormedAddCommGroup E'] [SeminormedAddCommGroup F'] [SeminormedAddCommGroup G']
[NormedAddCommGroup E''] [NormedAddCommGroup F''] [NormedAddCommGroup G''] [SeminormedRing R]
[SeminormedAddGroup E''']
[SeminormedRing R']
variable [NormedDivisionRing 𝕜] [NormedDivisionRing 𝕜']
variable {c c' c₁ c₂ : ℝ} {f : α → E} {g : α → F} {k : α → G}
variable {f' : α → E'} {g' : α → F'} {k' : α → G'}
variable {f'' : α → E''} {g'' : α → F''} {k'' : α → G''}
variable {l l' : Filter α}
section Defs
/-! ### Definitions -/
/-- This version of the Landau notation `IsBigOWith C l f g` where `f` and `g` are two functions on
a type `α` and `l` is a filter on `α`, means that eventually for `l`, `‖f‖` is bounded by `C * ‖g‖`.
In other words, `‖f‖ / ‖g‖` is eventually bounded by `C`, modulo division by zero issues that are
avoided by this definition. Probably you want to use `IsBigO` instead of this relation. -/
irreducible_def IsBigOWith (c : ℝ) (l : Filter α) (f : α → E) (g : α → F) : Prop :=
∀ᶠ x in l, ‖f x‖ ≤ c * ‖g x‖
#align asymptotics.is_O_with Asymptotics.IsBigOWith
/-- Definition of `IsBigOWith`. We record it in a lemma as `IsBigOWith` is irreducible. -/
theorem isBigOWith_iff : IsBigOWith c l f g ↔ ∀ᶠ x in l, ‖f x‖ ≤ c * ‖g x‖ := by rw [IsBigOWith_def]
#align asymptotics.is_O_with_iff Asymptotics.isBigOWith_iff
alias ⟨IsBigOWith.bound, IsBigOWith.of_bound⟩ := isBigOWith_iff
#align asymptotics.is_O_with.bound Asymptotics.IsBigOWith.bound
#align asymptotics.is_O_with.of_bound Asymptotics.IsBigOWith.of_bound
/-- The Landau notation `f =O[l] g` where `f` and `g` are two functions on a type `α` and `l` is
a filter on `α`, means that eventually for `l`, `‖f‖` is bounded by a constant multiple of `‖g‖`.
In other words, `‖f‖ / ‖g‖` is eventually bounded, modulo division by zero issues that are avoided
by this definition. -/
irreducible_def IsBigO (l : Filter α) (f : α → E) (g : α → F) : Prop :=
∃ c : ℝ, IsBigOWith c l f g
#align asymptotics.is_O Asymptotics.IsBigO
@[inherit_doc]
notation:100 f " =O[" l "] " g:100 => IsBigO l f g
/-- Definition of `IsBigO` in terms of `IsBigOWith`. We record it in a lemma as `IsBigO` is
irreducible. -/
| Mathlib/Analysis/Asymptotics/Asymptotics.lean | 109 | 109 | theorem isBigO_iff_isBigOWith : f =O[l] g ↔ ∃ c : ℝ, IsBigOWith c l f g := by | rw [IsBigO_def]
|
/-
Copyright (c) 2014 Robert Lewis. All rights reserved.
Released under Apache 2.0 license as described in the file LICENSE.
Authors: Robert Lewis, Leonardo de Moura, Johannes Hölzl, Mario Carneiro
-/
import Mathlib.Algebra.Field.Defs
import Mathlib.Algebra.GroupWithZero.Units.Lemmas
import Mathlib.Algebra.Ring.Commute
import Mathlib.Algebra.Ring.Invertible
import Mathlib.Order.Synonym
#align_import algebra.field.basic from "leanprover-community/mathlib"@"05101c3df9d9cfe9430edc205860c79b6d660102"
/-!
# Lemmas about division (semi)rings and (semi)fields
-/
open Function OrderDual Set
universe u
variable {α β K : Type*}
section DivisionSemiring
variable [DivisionSemiring α] {a b c d : α}
theorem add_div (a b c : α) : (a + b) / c = a / c + b / c := by simp_rw [div_eq_mul_inv, add_mul]
#align add_div add_div
@[field_simps]
theorem div_add_div_same (a b c : α) : a / c + b / c = (a + b) / c :=
(add_div _ _ _).symm
#align div_add_div_same div_add_div_same
theorem same_add_div (h : b ≠ 0) : (b + a) / b = 1 + a / b := by rw [← div_self h, add_div]
#align same_add_div same_add_div
theorem div_add_same (h : b ≠ 0) : (a + b) / b = a / b + 1 := by rw [← div_self h, add_div]
#align div_add_same div_add_same
theorem one_add_div (h : b ≠ 0) : 1 + a / b = (b + a) / b :=
(same_add_div h).symm
#align one_add_div one_add_div
theorem div_add_one (h : b ≠ 0) : a / b + 1 = (a + b) / b :=
(div_add_same h).symm
#align div_add_one div_add_one
/-- See `inv_add_inv` for the more convenient version when `K` is commutative. -/
theorem inv_add_inv' (ha : a ≠ 0) (hb : b ≠ 0) :
a⁻¹ + b⁻¹ = a⁻¹ * (a + b) * b⁻¹ :=
let _ := invertibleOfNonzero ha; let _ := invertibleOfNonzero hb; invOf_add_invOf a b
theorem one_div_mul_add_mul_one_div_eq_one_div_add_one_div (ha : a ≠ 0) (hb : b ≠ 0) :
1 / a * (a + b) * (1 / b) = 1 / a + 1 / b := by
simpa only [one_div] using (inv_add_inv' ha hb).symm
#align one_div_mul_add_mul_one_div_eq_one_div_add_one_div one_div_mul_add_mul_one_div_eq_one_div_add_one_div
theorem add_div_eq_mul_add_div (a b : α) (hc : c ≠ 0) : a + b / c = (a * c + b) / c :=
(eq_div_iff_mul_eq hc).2 <| by rw [right_distrib, div_mul_cancel₀ _ hc]
#align add_div_eq_mul_add_div add_div_eq_mul_add_div
@[field_simps]
theorem add_div' (a b c : α) (hc : c ≠ 0) : b + a / c = (b * c + a) / c := by
rw [add_div, mul_div_cancel_right₀ _ hc]
#align add_div' add_div'
@[field_simps]
theorem div_add' (a b c : α) (hc : c ≠ 0) : a / c + b = (a + b * c) / c := by
rwa [add_comm, add_div', add_comm]
#align div_add' div_add'
protected theorem Commute.div_add_div (hbc : Commute b c) (hbd : Commute b d) (hb : b ≠ 0)
(hd : d ≠ 0) : a / b + c / d = (a * d + b * c) / (b * d) := by
rw [add_div, mul_div_mul_right _ b hd, hbc.eq, hbd.eq, mul_div_mul_right c d hb]
#align commute.div_add_div Commute.div_add_div
protected theorem Commute.one_div_add_one_div (hab : Commute a b) (ha : a ≠ 0) (hb : b ≠ 0) :
1 / a + 1 / b = (a + b) / (a * b) := by
rw [(Commute.one_right a).div_add_div hab ha hb, one_mul, mul_one, add_comm]
#align commute.one_div_add_one_div Commute.one_div_add_one_div
protected theorem Commute.inv_add_inv (hab : Commute a b) (ha : a ≠ 0) (hb : b ≠ 0) :
a⁻¹ + b⁻¹ = (a + b) / (a * b) := by
rw [inv_eq_one_div, inv_eq_one_div, hab.one_div_add_one_div ha hb]
#align commute.inv_add_inv Commute.inv_add_inv
end DivisionSemiring
section DivisionMonoid
variable [DivisionMonoid K] [HasDistribNeg K] {a b : K}
theorem one_div_neg_one_eq_neg_one : (1 : K) / -1 = -1 :=
have : -1 * -1 = (1 : K) := by rw [neg_mul_neg, one_mul]
Eq.symm (eq_one_div_of_mul_eq_one_right this)
#align one_div_neg_one_eq_neg_one one_div_neg_one_eq_neg_one
| Mathlib/Algebra/Field/Basic.lean | 101 | 106 | theorem one_div_neg_eq_neg_one_div (a : K) : 1 / -a = -(1 / a) :=
calc
1 / -a = 1 / (-1 * a) := by | rw [neg_eq_neg_one_mul]
_ = 1 / a * (1 / -1) := by rw [one_div_mul_one_div_rev]
_ = 1 / a * -1 := by rw [one_div_neg_one_eq_neg_one]
_ = -(1 / a) := by rw [mul_neg, mul_one]
|
/-
Copyright (c) 2022 Andrew Yang. All rights reserved.
Released under Apache 2.0 license as described in the file LICENSE.
Authors: Andrew Yang
-/
import Mathlib.Data.ENat.Lattice
import Mathlib.Order.OrderIsoNat
import Mathlib.Tactic.TFAE
#align_import order.height from "leanprover-community/mathlib"@"bf27744463e9620ca4e4ebe951fe83530ae6949b"
/-!
# Maximal length of chains
This file contains lemmas to work with the maximal length of strictly descending finite
sequences (chains) in a partial order.
## Main definition
- `Set.subchain`: The set of strictly ascending lists of `α` contained in a `Set α`.
- `Set.chainHeight`: The maximal length of a strictly ascending sequence in a partial order.
This is defined as the maximum of the lengths of `Set.subchain`s, valued in `ℕ∞`.
## Main results
- `Set.exists_chain_of_le_chainHeight`: For each `n : ℕ` such that `n ≤ s.chainHeight`, there
exists `s.subchain` of length `n`.
- `Set.chainHeight_mono`: If `s ⊆ t` then `s.chainHeight ≤ t.chainHeight`.
- `Set.chainHeight_image`: If `f` is an order embedding, then
`(f '' s).chainHeight = s.chainHeight`.
- `Set.chainHeight_insert_of_forall_lt`: If `∀ y ∈ s, y < x`, then
`(insert x s).chainHeight = s.chainHeight + 1`.
- `Set.chainHeight_insert_of_forall_gt`: If `∀ y ∈ s, x < y`, then
`(insert x s).chainHeight = s.chainHeight + 1`.
- `Set.chainHeight_union_eq`: If `∀ x ∈ s, ∀ y ∈ t, s ≤ t`, then
`(s ∪ t).chainHeight = s.chainHeight + t.chainHeight`.
- `Set.wellFoundedGT_of_chainHeight_ne_top`:
If `s` has finite height, then `>` is well-founded on `s`.
- `Set.wellFoundedLT_of_chainHeight_ne_top`:
If `s` has finite height, then `<` is well-founded on `s`.
-/
open List hiding le_antisymm
open OrderDual
universe u v
variable {α β : Type*}
namespace Set
section LT
variable [LT α] [LT β] (s t : Set α)
/-- The set of strictly ascending lists of `α` contained in a `Set α`. -/
def subchain : Set (List α) :=
{ l | l.Chain' (· < ·) ∧ ∀ i ∈ l, i ∈ s }
#align set.subchain Set.subchain
@[simp] -- porting note: new `simp`
theorem nil_mem_subchain : [] ∈ s.subchain := ⟨trivial, fun _ ↦ nofun⟩
#align set.nil_mem_subchain Set.nil_mem_subchain
variable {s} {l : List α} {a : α}
theorem cons_mem_subchain_iff :
(a::l) ∈ s.subchain ↔ a ∈ s ∧ l ∈ s.subchain ∧ ∀ b ∈ l.head?, a < b := by
simp only [subchain, mem_setOf_eq, forall_mem_cons, chain'_cons', and_left_comm, and_comm,
and_assoc]
#align set.cons_mem_subchain_iff Set.cons_mem_subchain_iff
@[simp] -- Porting note (#10756): new lemma + `simp`
theorem singleton_mem_subchain_iff : [a] ∈ s.subchain ↔ a ∈ s := by simp [cons_mem_subchain_iff]
instance : Nonempty s.subchain :=
⟨⟨[], s.nil_mem_subchain⟩⟩
variable (s)
/-- The maximal length of a strictly ascending sequence in a partial order. -/
noncomputable def chainHeight : ℕ∞ :=
⨆ l ∈ s.subchain, length l
#align set.chain_height Set.chainHeight
theorem chainHeight_eq_iSup_subtype : s.chainHeight = ⨆ l : s.subchain, ↑l.1.length :=
iSup_subtype'
#align set.chain_height_eq_supr_subtype Set.chainHeight_eq_iSup_subtype
theorem exists_chain_of_le_chainHeight {n : ℕ} (hn : ↑n ≤ s.chainHeight) :
∃ l ∈ s.subchain, length l = n := by
rcases (le_top : s.chainHeight ≤ ⊤).eq_or_lt with ha | ha <;>
rw [chainHeight_eq_iSup_subtype] at ha
· obtain ⟨_, ⟨⟨l, h₁, h₂⟩, rfl⟩, h₃⟩ :=
not_bddAbove_iff'.mp (WithTop.iSup_coe_eq_top.1 ha) n
exact ⟨l.take n, ⟨h₁.take _, fun x h ↦ h₂ _ <| take_subset _ _ h⟩,
(l.length_take n).trans <| min_eq_left <| le_of_not_ge h₃⟩
· rw [ENat.iSup_coe_lt_top] at ha
obtain ⟨⟨l, h₁, h₂⟩, e : l.length = _⟩ := Nat.sSup_mem (Set.range_nonempty _) ha
refine
⟨l.take n, ⟨h₁.take _, fun x h ↦ h₂ _ <| take_subset _ _ h⟩,
(l.length_take n).trans <| min_eq_left <| ?_⟩
rwa [e, ← Nat.cast_le (α := ℕ∞), sSup_range, ENat.coe_iSup ha, ← chainHeight_eq_iSup_subtype]
#align set.exists_chain_of_le_chain_height Set.exists_chain_of_le_chainHeight
| Mathlib/Order/Height.lean | 109 | 114 | theorem le_chainHeight_TFAE (n : ℕ) :
TFAE [↑n ≤ s.chainHeight, ∃ l ∈ s.subchain, length l = n, ∃ l ∈ s.subchain, n ≤ length l] := by |
tfae_have 1 → 2; · exact s.exists_chain_of_le_chainHeight
tfae_have 2 → 3; · rintro ⟨l, hls, he⟩; exact ⟨l, hls, he.ge⟩
tfae_have 3 → 1; · rintro ⟨l, hs, hn⟩; exact le_iSup₂_of_le l hs (WithTop.coe_le_coe.2 hn)
tfae_finish
|
/-
Copyright (c) 2017 Johannes Hölzl. All rights reserved.
Released under Apache 2.0 license as described in the file LICENSE.
Authors: Shing Tak Lam, Yury Kudryashov
-/
import Mathlib.Algebra.MvPolynomial.Derivation
import Mathlib.Algebra.MvPolynomial.Variables
#align_import data.mv_polynomial.pderiv from "leanprover-community/mathlib"@"2f5b500a507264de86d666a5f87ddb976e2d8de4"
/-!
# Partial derivatives of polynomials
This file defines the notion of the formal *partial derivative* of a polynomial,
the derivative with respect to a single variable.
This derivative is not connected to the notion of derivative from analysis.
It is based purely on the polynomial exponents and coefficients.
## Main declarations
* `MvPolynomial.pderiv i p` : the partial derivative of `p` with respect to `i`, as a bundled
derivation of `MvPolynomial σ R`.
## Notation
As in other polynomial files, we typically use the notation:
+ `σ : Type*` (indexing the variables)
+ `R : Type*` `[CommRing R]` (the coefficients)
+ `s : σ →₀ ℕ`, a function from `σ` to `ℕ` which is zero away from a finite set.
This will give rise to a monomial in `MvPolynomial σ R` which mathematicians might call `X^s`
+ `a : R`
+ `i : σ`, with corresponding monomial `X i`, often denoted `X_i` by mathematicians
+ `p : MvPolynomial σ R`
-/
noncomputable section
universe u v
namespace MvPolynomial
open Set Function Finsupp
variable {R : Type u} {σ : Type v} {a a' a₁ a₂ : R} {s : σ →₀ ℕ}
section PDeriv
variable [CommSemiring R]
/-- `pderiv i p` is the partial derivative of `p` with respect to `i` -/
def pderiv (i : σ) : Derivation R (MvPolynomial σ R) (MvPolynomial σ R) :=
letI := Classical.decEq σ
mkDerivation R <| Pi.single i 1
#align mv_polynomial.pderiv MvPolynomial.pderiv
theorem pderiv_def [DecidableEq σ] (i : σ) : pderiv i = mkDerivation R (Pi.single i 1) := by
unfold pderiv; congr!
#align mv_polynomial.pderiv_def MvPolynomial.pderiv_def
@[simp]
| Mathlib/Algebra/MvPolynomial/PDeriv.lean | 69 | 77 | theorem pderiv_monomial {i : σ} :
pderiv i (monomial s a) = monomial (s - single i 1) (a * s i) := by |
classical
simp only [pderiv_def, mkDerivation_monomial, Finsupp.smul_sum, smul_eq_mul, ← smul_mul_assoc,
← (monomial _).map_smul]
refine (Finset.sum_eq_single i (fun j _ hne => ?_) fun hi => ?_).trans ?_
· simp [Pi.single_eq_of_ne hne]
· rw [Finsupp.not_mem_support_iff] at hi; simp [hi]
· simp
|
/-
Copyright (c) 2022 Yaël Dillies. All rights reserved.
Released under Apache 2.0 license as described in the file LICENSE.
Authors: Yaël Dillies
-/
import Mathlib.Data.Fintype.Card
import Mathlib.Order.UpperLower.Basic
#align_import combinatorics.set_family.intersecting from "leanprover-community/mathlib"@"d90e4e186f1d18e375dcd4e5b5f6364b01cb3e46"
/-!
# Intersecting families
This file defines intersecting families and proves their basic properties.
## Main declarations
* `Set.Intersecting`: Predicate for a set of elements in a generalized boolean algebra to be an
intersecting family.
* `Set.Intersecting.card_le`: An intersecting family can only take up to half the elements, because
`a` and `aᶜ` cannot simultaneously be in it.
* `Set.Intersecting.is_max_iff_card_eq`: Any maximal intersecting family takes up half the elements.
## References
* [D. J. Kleitman, *Families of non-disjoint subsets*][kleitman1966]
-/
open Finset
variable {α : Type*}
namespace Set
section SemilatticeInf
variable [SemilatticeInf α] [OrderBot α] {s t : Set α} {a b c : α}
/-- A set family is intersecting if every pair of elements is non-disjoint. -/
def Intersecting (s : Set α) : Prop :=
∀ ⦃a⦄, a ∈ s → ∀ ⦃b⦄, b ∈ s → ¬Disjoint a b
#align set.intersecting Set.Intersecting
@[mono]
theorem Intersecting.mono (h : t ⊆ s) (hs : s.Intersecting) : t.Intersecting := fun _a ha _b hb =>
hs (h ha) (h hb)
#align set.intersecting.mono Set.Intersecting.mono
theorem Intersecting.not_bot_mem (hs : s.Intersecting) : ⊥ ∉ s := fun h => hs h h disjoint_bot_left
#align set.intersecting.not_bot_mem Set.Intersecting.not_bot_mem
theorem Intersecting.ne_bot (hs : s.Intersecting) (ha : a ∈ s) : a ≠ ⊥ :=
ne_of_mem_of_not_mem ha hs.not_bot_mem
#align set.intersecting.ne_bot Set.Intersecting.ne_bot
theorem intersecting_empty : (∅ : Set α).Intersecting := fun _ => False.elim
#align set.intersecting_empty Set.intersecting_empty
@[simp]
theorem intersecting_singleton : ({a} : Set α).Intersecting ↔ a ≠ ⊥ := by simp [Intersecting]
#align set.intersecting_singleton Set.intersecting_singleton
protected theorem Intersecting.insert (hs : s.Intersecting) (ha : a ≠ ⊥)
(h : ∀ b ∈ s, ¬Disjoint a b) : (insert a s).Intersecting := by
rintro b (rfl | hb) c (rfl | hc)
· rwa [disjoint_self]
· exact h _ hc
· exact fun H => h _ hb H.symm
· exact hs hb hc
#align set.intersecting.insert Set.Intersecting.insert
theorem intersecting_insert :
(insert a s).Intersecting ↔ s.Intersecting ∧ a ≠ ⊥ ∧ ∀ b ∈ s, ¬Disjoint a b :=
⟨fun h =>
⟨h.mono <| subset_insert _ _, h.ne_bot <| mem_insert _ _, fun _b hb =>
h (mem_insert _ _) <| mem_insert_of_mem _ hb⟩,
fun h => h.1.insert h.2.1 h.2.2⟩
#align set.intersecting_insert Set.intersecting_insert
theorem intersecting_iff_pairwise_not_disjoint :
s.Intersecting ↔ (s.Pairwise fun a b => ¬Disjoint a b) ∧ s ≠ {⊥} := by
refine ⟨fun h => ⟨fun a ha b hb _ => h ha hb, ?_⟩, fun h a ha b hb hab => ?_⟩
· rintro rfl
exact intersecting_singleton.1 h rfl
have := h.1.eq ha hb (Classical.not_not.2 hab)
rw [this, disjoint_self] at hab
rw [hab] at hb
exact
h.2
(eq_singleton_iff_unique_mem.2
⟨hb, fun c hc => not_ne_iff.1 fun H => h.1 hb hc H.symm disjoint_bot_left⟩)
#align set.intersecting_iff_pairwise_not_disjoint Set.intersecting_iff_pairwise_not_disjoint
protected theorem Subsingleton.intersecting (hs : s.Subsingleton) : s.Intersecting ↔ s ≠ {⊥} :=
intersecting_iff_pairwise_not_disjoint.trans <| and_iff_right <| hs.pairwise _
#align set.subsingleton.intersecting Set.Subsingleton.intersecting
theorem intersecting_iff_eq_empty_of_subsingleton [Subsingleton α] (s : Set α) :
s.Intersecting ↔ s = ∅ := by
refine
subsingleton_of_subsingleton.intersecting.trans
⟨not_imp_comm.2 fun h => subsingleton_of_subsingleton.eq_singleton_of_mem ?_, ?_⟩
· obtain ⟨a, ha⟩ := nonempty_iff_ne_empty.2 h
rwa [Subsingleton.elim ⊥ a]
· rintro rfl
exact (Set.singleton_nonempty _).ne_empty.symm
#align set.intersecting_iff_eq_empty_of_subsingleton Set.intersecting_iff_eq_empty_of_subsingleton
/-- Maximal intersecting families are upper sets. -/
protected theorem Intersecting.isUpperSet (hs : s.Intersecting)
(h : ∀ t : Set α, t.Intersecting → s ⊆ t → s = t) : IsUpperSet s := by
classical
rintro a b hab ha
rw [h (Insert.insert b s) _ (subset_insert _ _)]
· exact mem_insert _ _
exact
hs.insert (mt (eq_bot_mono hab) <| hs.ne_bot ha) fun c hc hbc => hs ha hc <| hbc.mono_left hab
#align set.intersecting.is_upper_set Set.Intersecting.isUpperSet
/-- Maximal intersecting families are upper sets. Finset version. -/
| Mathlib/Combinatorics/SetFamily/Intersecting.lean | 122 | 130 | theorem Intersecting.isUpperSet' {s : Finset α} (hs : (s : Set α).Intersecting)
(h : ∀ t : Finset α, (t : Set α).Intersecting → s ⊆ t → s = t) : IsUpperSet (s : Set α) := by |
classical
rintro a b hab ha
rw [h (Insert.insert b s) _ (Finset.subset_insert _ _)]
· exact mem_insert_self _ _
rw [coe_insert]
exact
hs.insert (mt (eq_bot_mono hab) <| hs.ne_bot ha) fun c hc hbc => hs ha hc <| hbc.mono_left hab
|
/-
Copyright (c) 2020 Kenny Lau. All rights reserved.
Released under Apache 2.0 license as described in the file LICENSE.
Authors: Kenny Lau
-/
import Mathlib.Algebra.Polynomial.AlgebraMap
import Mathlib.Algebra.Polynomial.Monic
import Mathlib.Algebra.Ring.Action.Basic
import Mathlib.GroupTheory.GroupAction.Hom
import Mathlib.GroupTheory.GroupAction.Quotient
#align_import algebra.polynomial.group_ring_action from "leanprover-community/mathlib"@"afad8e438d03f9d89da2914aa06cb4964ba87a18"
/-!
# Group action on rings applied to polynomials
This file contains instances and definitions relating `MulSemiringAction` to `Polynomial`.
-/
variable (M : Type*) [Monoid M]
open Polynomial
namespace Polynomial
variable (R : Type*) [Semiring R]
variable {M}
-- Porting note: changed `(· • ·) m` to `HSMul.hSMul m`
theorem smul_eq_map [MulSemiringAction M R] (m : M) :
HSMul.hSMul m = map (MulSemiringAction.toRingHom M R m) := by
suffices DistribMulAction.toAddMonoidHom R[X] m =
(mapRingHom (MulSemiringAction.toRingHom M R m)).toAddMonoidHom by
ext1 r
exact DFunLike.congr_fun this r
ext n r : 2
change m • monomial n r = map (MulSemiringAction.toRingHom M R m) (monomial n r)
rw [Polynomial.map_monomial, Polynomial.smul_monomial, MulSemiringAction.toRingHom_apply]
#align polynomial.smul_eq_map Polynomial.smul_eq_map
variable (M)
noncomputable instance [MulSemiringAction M R] : MulSemiringAction M R[X] :=
{ Polynomial.distribMulAction with
smul_one := fun m ↦
smul_eq_map R m ▸ Polynomial.map_one (MulSemiringAction.toRingHom M R m)
smul_mul := fun m _ _ ↦
smul_eq_map R m ▸ Polynomial.map_mul (MulSemiringAction.toRingHom M R m) }
variable {M R}
variable [MulSemiringAction M R]
@[simp]
theorem smul_X (m : M) : (m • X : R[X]) = X :=
(smul_eq_map R m).symm ▸ map_X _
set_option linter.uppercaseLean3 false in
#align polynomial.smul_X Polynomial.smul_X
variable (S : Type*) [CommSemiring S] [MulSemiringAction M S]
theorem smul_eval_smul (m : M) (f : S[X]) (x : S) : (m • f).eval (m • x) = m • f.eval x :=
Polynomial.induction_on f (fun r ↦ by rw [smul_C, eval_C, eval_C])
(fun f g ihf ihg ↦ by rw [smul_add, eval_add, ihf, ihg, eval_add, smul_add]) fun n r _ ↦ by
rw [smul_mul', smul_pow', smul_C, smul_X, eval_mul, eval_C, eval_pow, eval_X, eval_mul, eval_C,
eval_pow, eval_X, smul_mul', smul_pow']
#align polynomial.smul_eval_smul Polynomial.smul_eval_smul
variable (G : Type*) [Group G]
theorem eval_smul' [MulSemiringAction G S] (g : G) (f : S[X]) (x : S) :
f.eval (g • x) = g • (g⁻¹ • f).eval x := by
rw [← smul_eval_smul, smul_inv_smul]
#align polynomial.eval_smul' Polynomial.eval_smul'
theorem smul_eval [MulSemiringAction G S] (g : G) (f : S[X]) (x : S) :
(g • f).eval x = g • f.eval (g⁻¹ • x) := by
rw [← smul_eval_smul, smul_inv_smul]
#align polynomial.smul_eval Polynomial.smul_eval
end Polynomial
section CommRing
set_option linter.uppercaseLean3 false -- Porting note: `prod_X_*`
variable (G : Type*) [Group G] [Fintype G]
variable (R : Type*) [CommRing R] [MulSemiringAction G R]
open MulAction
/-- the product of `(X - g • x)` over distinct `g • x`. -/
noncomputable def prodXSubSMul (x : R) : R[X] :=
letI := Classical.decEq R
(Finset.univ : Finset (G ⧸ MulAction.stabilizer G x)).prod fun g ↦
Polynomial.X - Polynomial.C (ofQuotientStabilizer G x g)
#align prod_X_sub_smul prodXSubSMul
theorem prodXSubSMul.monic (x : R) : (prodXSubSMul G R x).Monic :=
Polynomial.monic_prod_of_monic _ _ fun _ _ ↦ Polynomial.monic_X_sub_C _
#align prod_X_sub_smul.monic prodXSubSMul.monic
theorem prodXSubSMul.eval (x : R) : (prodXSubSMul G R x).eval x = 0 :=
letI := Classical.decEq R
(map_prod ((Polynomial.aeval x).toRingHom.toMonoidHom : R[X] →* R) _ _).trans <|
Finset.prod_eq_zero (Finset.mem_univ <| QuotientGroup.mk 1) <| by simp
#align prod_X_sub_smul.eval prodXSubSMul.eval
theorem prodXSubSMul.smul (x : R) (g : G) : g • prodXSubSMul G R x = prodXSubSMul G R x :=
letI := Classical.decEq R
Finset.smul_prod.trans <|
Fintype.prod_bijective _ (MulAction.bijective g) _ _ fun g' ↦ by
rw [ofQuotientStabilizer_smul, smul_sub, Polynomial.smul_X, Polynomial.smul_C]
#align prod_X_sub_smul.smul prodXSubSMul.smul
| Mathlib/Algebra/Polynomial/GroupRingAction.lean | 115 | 117 | theorem prodXSubSMul.coeff (x : R) (g : G) (n : ℕ) :
g • (prodXSubSMul G R x).coeff n = (prodXSubSMul G R x).coeff n := by |
rw [← Polynomial.coeff_smul, prodXSubSMul.smul]
|
/-
Copyright (c) 2017 Johannes Hölzl. All rights reserved.
Released under Apache 2.0 license as described in the file LICENSE.
Authors: Johannes Hölzl
-/
import Mathlib.Topology.Algebra.InfiniteSum.Group
import Mathlib.Logic.Encodable.Lattice
/-!
# Infinite sums and products over `ℕ` and `ℤ`
This file contains lemmas about `HasSum`, `Summable`, `tsum`, `HasProd`, `Multipliable`, and `tprod`
applied to the important special cases where the domain is `ℕ` or `ℤ`. For instance, we prove the
formula `∑ i ∈ range k, f i + ∑' i, f (i + k) = ∑' i, f i`, ∈ `sum_add_tsum_nat_add`, as well as
several results relating sums and products on `ℕ` to sums and products on `ℤ`.
-/
noncomputable section
open Filter Finset Function Encodable
open scoped Topology
variable {M : Type*} [CommMonoid M] [TopologicalSpace M] {m m' : M}
variable {G : Type*} [CommGroup G] {g g' : G}
-- don't declare [TopologicalAddGroup G] here as some results require [UniformAddGroup G] instead
/-!
## Sums over `ℕ`
-/
section Nat
section Monoid
namespace HasProd
/-- If `f : ℕ → M` has product `m`, then the partial products `∏ i ∈ range n, f i` converge
to `m`. -/
@[to_additive "If `f : ℕ → M` has sum `m`, then the partial sums `∑ i ∈ range n, f i` converge
to `m`."]
theorem tendsto_prod_nat {f : ℕ → M} (h : HasProd f m) :
Tendsto (fun n ↦ ∏ i ∈ range n, f i) atTop (𝓝 m) :=
h.comp tendsto_finset_range
#align has_sum.tendsto_sum_nat HasSum.tendsto_sum_nat
/-- If `f : ℕ → M` is multipliable, then the partial products `∏ i ∈ range n, f i` converge
to `∏' i, f i`. -/
@[to_additive "If `f : ℕ → M` is summable, then the partial sums `∑ i ∈ range n, f i` converge
to `∑' i, f i`."]
theorem Multipliable.tendsto_prod_tprod_nat {f : ℕ → M} (h : Multipliable f) :
Tendsto (fun n ↦ ∏ i ∈ range n, f i) atTop (𝓝 (∏' i, f i)) :=
tendsto_prod_nat h.hasProd
section ContinuousMul
variable [ContinuousMul M]
@[to_additive]
theorem prod_range_mul {f : ℕ → M} {k : ℕ} (h : HasProd (fun n ↦ f (n + k)) m) :
HasProd f ((∏ i ∈ range k, f i) * m) := by
refine ((range k).hasProd f).mul_compl ?_
rwa [← (notMemRangeEquiv k).symm.hasProd_iff]
@[to_additive]
theorem zero_mul {f : ℕ → M} (h : HasProd (fun n ↦ f (n + 1)) m) :
HasProd f (f 0 * m) := by
simpa only [prod_range_one] using h.prod_range_mul
@[to_additive]
theorem even_mul_odd {f : ℕ → M} (he : HasProd (fun k ↦ f (2 * k)) m)
(ho : HasProd (fun k ↦ f (2 * k + 1)) m') : HasProd f (m * m') := by
have := mul_right_injective₀ (two_ne_zero' ℕ)
replace ho := ((add_left_injective 1).comp this).hasProd_range_iff.2 ho
refine (this.hasProd_range_iff.2 he).mul_isCompl ?_ ho
simpa [(· ∘ ·)] using Nat.isCompl_even_odd
#align has_sum.even_add_odd HasSum.even_add_odd
end ContinuousMul
end HasProd
namespace Multipliable
@[to_additive]
| Mathlib/Topology/Algebra/InfiniteSum/NatInt.lean | 88 | 92 | theorem hasProd_iff_tendsto_nat [T2Space M] {f : ℕ → M} (hf : Multipliable f) :
HasProd f m ↔ Tendsto (fun n : ℕ ↦ ∏ i ∈ range n, f i) atTop (𝓝 m) := by |
refine ⟨fun h ↦ h.tendsto_prod_nat, fun h ↦ ?_⟩
rw [tendsto_nhds_unique h hf.hasProd.tendsto_prod_nat]
exact hf.hasProd
|
/-
Copyright (c) 2014 Jeremy Avigad. All rights reserved.
Released under Apache 2.0 license as described in the file LICENSE.
Authors: Jeremy Avigad, Leonardo de Moura, Mario Carneiro
-/
/-!
# Definitions and properties of `coprime`
-/
namespace Nat
/-!
### `coprime`
See also `nat.coprime_of_dvd` and `nat.coprime_of_dvd'` to prove `nat.Coprime m n`.
-/
/-- `m` and `n` are coprime, or relatively prime, if their `gcd` is 1. -/
@[reducible] def Coprime (m n : Nat) : Prop := gcd m n = 1
instance (m n : Nat) : Decidable (Coprime m n) := inferInstanceAs (Decidable (_ = 1))
theorem coprime_iff_gcd_eq_one : Coprime m n ↔ gcd m n = 1 := .rfl
theorem Coprime.gcd_eq_one : Coprime m n → gcd m n = 1 := id
theorem Coprime.symm : Coprime n m → Coprime m n := (gcd_comm m n).trans
theorem coprime_comm : Coprime n m ↔ Coprime m n := ⟨Coprime.symm, Coprime.symm⟩
theorem Coprime.dvd_of_dvd_mul_right (H1 : Coprime k n) (H2 : k ∣ m * n) : k ∣ m := by
let t := dvd_gcd (Nat.dvd_mul_left k m) H2
rwa [gcd_mul_left, H1.gcd_eq_one, Nat.mul_one] at t
theorem Coprime.dvd_of_dvd_mul_left (H1 : Coprime k m) (H2 : k ∣ m * n) : k ∣ n :=
H1.dvd_of_dvd_mul_right (by rwa [Nat.mul_comm])
theorem Coprime.gcd_mul_left_cancel (m : Nat) (H : Coprime k n) : gcd (k * m) n = gcd m n :=
have H1 : Coprime (gcd (k * m) n) k := by
rw [Coprime, Nat.gcd_assoc, H.symm.gcd_eq_one, gcd_one_right]
Nat.dvd_antisymm
(dvd_gcd (H1.dvd_of_dvd_mul_left (gcd_dvd_left _ _)) (gcd_dvd_right _ _))
(gcd_dvd_gcd_mul_left _ _ _)
theorem Coprime.gcd_mul_right_cancel (m : Nat) (H : Coprime k n) : gcd (m * k) n = gcd m n := by
rw [Nat.mul_comm m k, H.gcd_mul_left_cancel m]
theorem Coprime.gcd_mul_left_cancel_right (n : Nat)
(H : Coprime k m) : gcd m (k * n) = gcd m n := by
rw [gcd_comm m n, gcd_comm m (k * n), H.gcd_mul_left_cancel n]
theorem Coprime.gcd_mul_right_cancel_right (n : Nat)
(H : Coprime k m) : gcd m (n * k) = gcd m n := by
rw [Nat.mul_comm n k, H.gcd_mul_left_cancel_right n]
theorem coprime_div_gcd_div_gcd
(H : 0 < gcd m n) : Coprime (m / gcd m n) (n / gcd m n) := by
rw [coprime_iff_gcd_eq_one, gcd_div (gcd_dvd_left m n) (gcd_dvd_right m n), Nat.div_self H]
theorem not_coprime_of_dvd_of_dvd (dgt1 : 1 < d) (Hm : d ∣ m) (Hn : d ∣ n) : ¬ Coprime m n :=
fun co => Nat.not_le_of_gt dgt1 <| Nat.le_of_dvd Nat.zero_lt_one <| by
rw [← co.gcd_eq_one]; exact dvd_gcd Hm Hn
theorem exists_coprime (m n : Nat) :
∃ m' n', Coprime m' n' ∧ m = m' * gcd m n ∧ n = n' * gcd m n := by
cases eq_zero_or_pos (gcd m n) with
| inl h0 =>
rw [gcd_eq_zero_iff] at h0
refine ⟨1, 1, gcd_one_left 1, ?_⟩
simp [h0]
| inr hpos =>
exact ⟨_, _, coprime_div_gcd_div_gcd hpos,
(Nat.div_mul_cancel (gcd_dvd_left m n)).symm,
(Nat.div_mul_cancel (gcd_dvd_right m n)).symm⟩
theorem exists_coprime' (H : 0 < gcd m n) :
∃ g m' n', 0 < g ∧ Coprime m' n' ∧ m = m' * g ∧ n = n' * g :=
let ⟨m', n', h⟩ := exists_coprime m n; ⟨_, m', n', H, h⟩
theorem Coprime.mul (H1 : Coprime m k) (H2 : Coprime n k) : Coprime (m * n) k :=
(H1.gcd_mul_left_cancel n).trans H2
theorem Coprime.mul_right (H1 : Coprime k m) (H2 : Coprime k n) : Coprime k (m * n) :=
(H1.symm.mul H2.symm).symm
theorem Coprime.coprime_dvd_left (H1 : m ∣ k) (H2 : Coprime k n) : Coprime m n := by
apply eq_one_of_dvd_one
rw [Coprime] at H2
have := Nat.gcd_dvd_gcd_of_dvd_left n H1
rwa [← H2]
theorem Coprime.coprime_dvd_right (H1 : n ∣ m) (H2 : Coprime k m) : Coprime k n :=
(H2.symm.coprime_dvd_left H1).symm
theorem Coprime.coprime_mul_left (H : Coprime (k * m) n) : Coprime m n :=
H.coprime_dvd_left (Nat.dvd_mul_left _ _)
theorem Coprime.coprime_mul_right (H : Coprime (m * k) n) : Coprime m n :=
H.coprime_dvd_left (Nat.dvd_mul_right _ _)
theorem Coprime.coprime_mul_left_right (H : Coprime m (k * n)) : Coprime m n :=
H.coprime_dvd_right (Nat.dvd_mul_left _ _)
theorem Coprime.coprime_mul_right_right (H : Coprime m (n * k)) : Coprime m n :=
H.coprime_dvd_right (Nat.dvd_mul_right _ _)
| .lake/packages/batteries/Batteries/Data/Nat/Gcd.lean | 108 | 118 | theorem Coprime.coprime_div_left (cmn : Coprime m n) (dvd : a ∣ m) : Coprime (m / a) n := by |
match eq_zero_or_pos a with
| .inl h0 =>
rw [h0] at dvd
rw [Nat.eq_zero_of_zero_dvd dvd] at cmn ⊢
simp; assumption
| .inr hpos =>
let ⟨k, hk⟩ := dvd
rw [hk, Nat.mul_div_cancel_left _ hpos]
rw [hk] at cmn
exact cmn.coprime_mul_left
|
/-
Copyright (c) 2020 Markus Himmel. All rights reserved.
Released under Apache 2.0 license as described in the file LICENSE.
Authors: Markus Himmel, Scott Morrison
-/
import Mathlib.CategoryTheory.Preadditive.Yoneda.Basic
import Mathlib.CategoryTheory.Preadditive.Injective
import Mathlib.Algebra.Category.GroupCat.EpiMono
import Mathlib.Algebra.Category.ModuleCat.EpiMono
#align_import category_theory.preadditive.yoneda.injective from "leanprover-community/mathlib"@"f8d8465c3c392a93b9ed226956e26dee00975946"
/-!
An object is injective iff the preadditive yoneda functor on it preserves epimorphisms.
-/
universe v u
open Opposite
namespace CategoryTheory
variable {C : Type u} [Category.{v} C]
section Preadditive
variable [Preadditive C]
namespace Injective
theorem injective_iff_preservesEpimorphisms_preadditiveYoneda_obj (J : C) :
Injective J ↔ (preadditiveYoneda.obj J).PreservesEpimorphisms := by
rw [injective_iff_preservesEpimorphisms_yoneda_obj]
refine
⟨fun h : (preadditiveYoneda.obj J ⋙ (forget AddCommGroupCat)).PreservesEpimorphisms => ?_, ?_⟩
· exact
Functor.preservesEpimorphisms_of_preserves_of_reflects (preadditiveYoneda.obj J) (forget _)
· intro
exact (inferInstance : (preadditiveYoneda.obj J ⋙ forget _).PreservesEpimorphisms)
#align category_theory.injective.injective_iff_preserves_epimorphisms_preadditive_yoneda_obj CategoryTheory.Injective.injective_iff_preservesEpimorphisms_preadditiveYoneda_obj
| Mathlib/CategoryTheory/Preadditive/Yoneda/Injective.lean | 43 | 51 | theorem injective_iff_preservesEpimorphisms_preadditive_yoneda_obj' (J : C) :
Injective J ↔ (preadditiveYonedaObj J).PreservesEpimorphisms := by |
rw [injective_iff_preservesEpimorphisms_yoneda_obj]
refine ⟨fun h : (preadditiveYonedaObj J ⋙ (forget <| ModuleCat (End J))).PreservesEpimorphisms =>
?_, ?_⟩
· exact
Functor.preservesEpimorphisms_of_preserves_of_reflects (preadditiveYonedaObj J) (forget _)
· intro
exact (inferInstance : (preadditiveYonedaObj J ⋙ forget _).PreservesEpimorphisms)
|
/-
Copyright (c) 2018 Chris Hughes. All rights reserved.
Released under Apache 2.0 license as described in the file LICENSE.
Authors: Chris Hughes, Abhimanyu Pallavi Sudhir, Jean Lo, Calle Sönne, Benjamin Davidson
-/
import Mathlib.Analysis.SpecialFunctions.Trigonometric.Inverse
import Mathlib.Analysis.SpecialFunctions.Trigonometric.Deriv
#align_import analysis.special_functions.trigonometric.inverse_deriv from "leanprover-community/mathlib"@"f2ce6086713c78a7f880485f7917ea547a215982"
/-!
# derivatives of the inverse trigonometric functions
Derivatives of `arcsin` and `arccos`.
-/
noncomputable section
open scoped Classical Topology Filter
open Set Filter
open scoped Real
namespace Real
section Arcsin
theorem deriv_arcsin_aux {x : ℝ} (h₁ : x ≠ -1) (h₂ : x ≠ 1) :
HasStrictDerivAt arcsin (1 / √(1 - x ^ 2)) x ∧ ContDiffAt ℝ ⊤ arcsin x := by
cases' h₁.lt_or_lt with h₁ h₁
· have : 1 - x ^ 2 < 0 := by nlinarith [h₁]
rw [sqrt_eq_zero'.2 this.le, div_zero]
have : arcsin =ᶠ[𝓝 x] fun _ => -(π / 2) :=
(gt_mem_nhds h₁).mono fun y hy => arcsin_of_le_neg_one hy.le
exact ⟨(hasStrictDerivAt_const _ _).congr_of_eventuallyEq this.symm,
contDiffAt_const.congr_of_eventuallyEq this⟩
cases' h₂.lt_or_lt with h₂ h₂
· have : 0 < √(1 - x ^ 2) := sqrt_pos.2 (by nlinarith [h₁, h₂])
simp only [← cos_arcsin, one_div] at this ⊢
exact ⟨sinPartialHomeomorph.hasStrictDerivAt_symm ⟨h₁, h₂⟩ this.ne' (hasStrictDerivAt_sin _),
sinPartialHomeomorph.contDiffAt_symm_deriv this.ne' ⟨h₁, h₂⟩ (hasDerivAt_sin _)
contDiff_sin.contDiffAt⟩
· have : 1 - x ^ 2 < 0 := by nlinarith [h₂]
rw [sqrt_eq_zero'.2 this.le, div_zero]
have : arcsin =ᶠ[𝓝 x] fun _ => π / 2 := (lt_mem_nhds h₂).mono fun y hy => arcsin_of_one_le hy.le
exact ⟨(hasStrictDerivAt_const _ _).congr_of_eventuallyEq this.symm,
contDiffAt_const.congr_of_eventuallyEq this⟩
#align real.deriv_arcsin_aux Real.deriv_arcsin_aux
theorem hasStrictDerivAt_arcsin {x : ℝ} (h₁ : x ≠ -1) (h₂ : x ≠ 1) :
HasStrictDerivAt arcsin (1 / √(1 - x ^ 2)) x :=
(deriv_arcsin_aux h₁ h₂).1
#align real.has_strict_deriv_at_arcsin Real.hasStrictDerivAt_arcsin
theorem hasDerivAt_arcsin {x : ℝ} (h₁ : x ≠ -1) (h₂ : x ≠ 1) :
HasDerivAt arcsin (1 / √(1 - x ^ 2)) x :=
(hasStrictDerivAt_arcsin h₁ h₂).hasDerivAt
#align real.has_deriv_at_arcsin Real.hasDerivAt_arcsin
theorem contDiffAt_arcsin {x : ℝ} (h₁ : x ≠ -1) (h₂ : x ≠ 1) {n : ℕ∞} : ContDiffAt ℝ n arcsin x :=
(deriv_arcsin_aux h₁ h₂).2.of_le le_top
#align real.cont_diff_at_arcsin Real.contDiffAt_arcsin
| Mathlib/Analysis/SpecialFunctions/Trigonometric/InverseDeriv.lean | 66 | 71 | theorem hasDerivWithinAt_arcsin_Ici {x : ℝ} (h : x ≠ -1) :
HasDerivWithinAt arcsin (1 / √(1 - x ^ 2)) (Ici x) x := by |
rcases eq_or_ne x 1 with (rfl | h')
· convert (hasDerivWithinAt_const (1 : ℝ) _ (π / 2)).congr _ _ <;>
simp (config := { contextual := true }) [arcsin_of_one_le]
· exact (hasDerivAt_arcsin h h').hasDerivWithinAt
|
/-
Copyright (c) 2022 Riccardo Brasca. All rights reserved.
Released under Apache 2.0 license as described in the file LICENSE.
Authors: Alex Best, Riccardo Brasca, Eric Rodriguez
-/
import Mathlib.Data.PNat.Prime
import Mathlib.Algebra.IsPrimePow
import Mathlib.NumberTheory.Cyclotomic.Basic
import Mathlib.RingTheory.Adjoin.PowerBasis
import Mathlib.RingTheory.Polynomial.Cyclotomic.Eval
import Mathlib.RingTheory.Norm
import Mathlib.RingTheory.Polynomial.Cyclotomic.Expand
#align_import number_theory.cyclotomic.primitive_roots from "leanprover-community/mathlib"@"5bfbcca0a7ffdd21cf1682e59106d6c942434a32"
/-!
# Primitive roots in cyclotomic fields
If `IsCyclotomicExtension {n} A B`, we define an element `zeta n A B : B` that is a primitive
`n`th-root of unity in `B` and we study its properties. We also prove related theorems under the
more general assumption of just being a primitive root, for reasons described in the implementation
details section.
## Main definitions
* `IsCyclotomicExtension.zeta n A B`: if `IsCyclotomicExtension {n} A B`, than `zeta n A B`
is a primitive `n`-th root of unity in `B`.
* `IsPrimitiveRoot.powerBasis`: if `K` and `L` are fields such that
`IsCyclotomicExtension {n} K L`, then `IsPrimitiveRoot.powerBasis`
gives a `K`-power basis for `L` given a primitive root `ζ`.
* `IsPrimitiveRoot.embeddingsEquivPrimitiveRoots`: the equivalence between `L →ₐ[K] A`
and `primitiveroots n A` given by the choice of `ζ`.
## Main results
* `IsCyclotomicExtension.zeta_spec`: `zeta n A B` is a primitive `n`-th root of unity.
* `IsCyclotomicExtension.finrank`: if `Irreducible (cyclotomic n K)` (in particular for
`K = ℚ`), then the `finrank` of a cyclotomic extension is `n.totient`.
* `IsPrimitiveRoot.norm_eq_one`: if `Irreducible (cyclotomic n K)` (in particular for `K = ℚ`),
the norm of a primitive root is `1` if `n ≠ 2`.
* `IsPrimitiveRoot.sub_one_norm_eq_eval_cyclotomic`: if `Irreducible (cyclotomic n K)`
(in particular for `K = ℚ`), then the norm of `ζ - 1` is `eval 1 (cyclotomic n ℤ)`, for a
primitive root `ζ`. We also prove the analogous of this result for `zeta`.
* `IsPrimitiveRoot.norm_pow_sub_one_of_prime_pow_ne_two` : if
`Irreducible (cyclotomic (p ^ (k + 1)) K)` (in particular for `K = ℚ`) and `p` is a prime,
then the norm of `ζ ^ (p ^ s) - 1` is `p ^ (p ^ s)` `p ^ (k - s + 1) ≠ 2`. See the following
lemmas for similar results. We also prove the analogous of this result for `zeta`.
* `IsPrimitiveRoot.norm_sub_one_of_prime_ne_two` : if `Irreducible (cyclotomic (p ^ (k + 1)) K)`
(in particular for `K = ℚ`) and `p` is an odd prime, then the norm of `ζ - 1` is `p`. We also
prove the analogous of this result for `zeta`.
* `IsPrimitiveRoot.embeddingsEquivPrimitiveRoots`: the equivalence between `L →ₐ[K] A`
and `primitiveRoots n A` given by the choice of `ζ`.
## Implementation details
`zeta n A B` is defined as any primitive root of unity in `B`, - this must exist, by definition of
`IsCyclotomicExtension`. It is not true in general that it is a root of `cyclotomic n B`,
but this holds if `isDomain B` and `NeZero (↑n : B)`.
`zeta n A B` is defined using `Exists.choose`, which means we cannot control it.
For example, in normal mathematics, we can demand that `(zeta p ℤ ℤ[ζₚ] : ℚ(ζₚ))` is equal to
`zeta p ℚ ℚ(ζₚ)`, as we are just choosing "an arbitrary primitive root" and we can internally
specify that our choices agree. This is not the case here, and it is indeed impossible to prove that
these two are equal. Therefore, whenever possible, we prove our results for any primitive root,
and only at the "final step", when we need to provide an "explicit" primitive root, we use `zeta`.
-/
open Polynomial Algebra Finset FiniteDimensional IsCyclotomicExtension Nat PNat Set
open scoped IntermediateField
universe u v w z
variable {p n : ℕ+} (A : Type w) (B : Type z) (K : Type u) {L : Type v} (C : Type w)
variable [CommRing A] [CommRing B] [Algebra A B] [IsCyclotomicExtension {n} A B]
section Zeta
namespace IsCyclotomicExtension
variable (n)
/-- If `B` is an `n`-th cyclotomic extension of `A`, then `zeta n A B` is a primitive root of
unity in `B`. -/
noncomputable def zeta : B :=
(exists_prim_root A <| Set.mem_singleton n : ∃ r : B, IsPrimitiveRoot r n).choose
#align is_cyclotomic_extension.zeta IsCyclotomicExtension.zeta
/-- `zeta n A B` is a primitive `n`-th root of unity. -/
@[simp]
theorem zeta_spec : IsPrimitiveRoot (zeta n A B) n :=
Classical.choose_spec (exists_prim_root A (Set.mem_singleton n) : ∃ r : B, IsPrimitiveRoot r n)
#align is_cyclotomic_extension.zeta_spec IsCyclotomicExtension.zeta_spec
theorem aeval_zeta [IsDomain B] [NeZero ((n : ℕ) : B)] :
aeval (zeta n A B) (cyclotomic n A) = 0 := by
rw [aeval_def, ← eval_map, ← IsRoot.def, map_cyclotomic, isRoot_cyclotomic_iff]
exact zeta_spec n A B
#align is_cyclotomic_extension.aeval_zeta IsCyclotomicExtension.aeval_zeta
| Mathlib/NumberTheory/Cyclotomic/PrimitiveRoots.lean | 98 | 100 | theorem zeta_isRoot [IsDomain B] [NeZero ((n : ℕ) : B)] : IsRoot (cyclotomic n B) (zeta n A B) := by |
convert aeval_zeta n A B using 0
rw [IsRoot.def, aeval_def, eval₂_eq_eval_map, map_cyclotomic]
|
/-
Copyright (c) 2021 François Sunatori. All rights reserved.
Released under Apache 2.0 license as described in the file LICENSE.
Authors: François Sunatori
-/
import Mathlib.Analysis.Complex.Circle
import Mathlib.LinearAlgebra.Determinant
import Mathlib.LinearAlgebra.Matrix.GeneralLinearGroup
#align_import analysis.complex.isometry from "leanprover-community/mathlib"@"ae690b0c236e488a0043f6faa8ce3546e7f2f9c5"
/-!
# Isometries of the Complex Plane
The lemma `linear_isometry_complex` states the classification of isometries in the complex plane.
Specifically, isometries with rotations but without translation.
The proof involves:
1. creating a linear isometry `g` with two fixed points, `g(0) = 0`, `g(1) = 1`
2. applying `linear_isometry_complex_aux` to `g`
The proof of `linear_isometry_complex_aux` is separated in the following parts:
1. show that the real parts match up: `LinearIsometry.re_apply_eq_re`
2. show that I maps to either I or -I
3. every z is a linear combination of a + b * I
## References
* [Isometries of the Complex Plane](http://helmut.knaust.info/mediawiki/images/b/b5/Iso.pdf)
-/
noncomputable section
open Complex
open ComplexConjugate
local notation "|" x "|" => Complex.abs x
/-- An element of the unit circle defines a `LinearIsometryEquiv` from `ℂ` to itself, by
rotation. -/
def rotation : circle →* ℂ ≃ₗᵢ[ℝ] ℂ where
toFun a :=
{ DistribMulAction.toLinearEquiv ℝ ℂ a with
norm_map' := fun x => show |a * x| = |x| by rw [map_mul, abs_coe_circle, one_mul] }
map_one' := LinearIsometryEquiv.ext <| one_smul circle
map_mul' a b := LinearIsometryEquiv.ext <| mul_smul a b
#align rotation rotation
@[simp]
theorem rotation_apply (a : circle) (z : ℂ) : rotation a z = a * z :=
rfl
#align rotation_apply rotation_apply
@[simp]
theorem rotation_symm (a : circle) : (rotation a).symm = rotation a⁻¹ :=
LinearIsometryEquiv.ext fun _ => rfl
#align rotation_symm rotation_symm
@[simp]
theorem rotation_trans (a b : circle) : (rotation a).trans (rotation b) = rotation (b * a) := by
ext1
simp
#align rotation_trans rotation_trans
| Mathlib/Analysis/Complex/Isometry.lean | 65 | 71 | theorem rotation_ne_conjLIE (a : circle) : rotation a ≠ conjLIE := by |
intro h
have h1 : rotation a 1 = conj 1 := LinearIsometryEquiv.congr_fun h 1
have hI : rotation a I = conj I := LinearIsometryEquiv.congr_fun h I
rw [rotation_apply, RingHom.map_one, mul_one] at h1
rw [rotation_apply, conj_I, ← neg_one_mul, mul_left_inj' I_ne_zero, h1, eq_neg_self_iff] at hI
exact one_ne_zero hI
|
/-
Copyright (c) 2022 Riccardo Brasca. All rights reserved.
Released under Apache 2.0 license as described in the file LICENSE.
Authors: Riccardo Brasca, Eric Rodriguez
-/
import Mathlib.NumberTheory.NumberField.Basic
import Mathlib.RingTheory.Localization.NormTrace
#align_import number_theory.number_field.norm from "leanprover-community/mathlib"@"00f91228655eecdcd3ac97a7fd8dbcb139fe990a"
/-!
# Norm in number fields
Given a finite extension of number fields, we define the norm morphism as a function between the
rings of integers.
## Main definitions
* `RingOfIntegers.norm K` : `Algebra.norm` as a morphism `(𝓞 L) →* (𝓞 K)`.
## Main results
* `RingOfIntegers.dvd_norm` : if `L/K` is a finite Galois extension of fields, then, for all
`(x : 𝓞 L)` we have that `x ∣ algebraMap (𝓞 K) (𝓞 L) (norm K x)`.
-/
open scoped NumberField
open Finset NumberField Algebra FiniteDimensional
section Rat
variable {K : Type*} [Field K] [NumberField K] (x : 𝓞 K)
theorem Algebra.coe_norm_int : (Algebra.norm ℤ x : ℚ) = Algebra.norm ℚ (x : K) :=
(Algebra.norm_localization (R := ℤ) (Rₘ := ℚ) (S := 𝓞 K) (Sₘ := K) (nonZeroDivisors ℤ) x).symm
theorem Algebra.coe_trace_int : (Algebra.trace ℤ _ x : ℚ) = Algebra.trace ℚ K (x : K) :=
(Algebra.trace_localization (R := ℤ) (Rₘ := ℚ) (S := 𝓞 K) (Sₘ := K) (nonZeroDivisors ℤ) x).symm
end Rat
namespace RingOfIntegers
variable {L : Type*} (K : Type*) [Field K] [Field L] [Algebra K L] [FiniteDimensional K L]
/-- `Algebra.norm` as a morphism betwen the rings of integers. -/
noncomputable def norm [IsSeparable K L] : 𝓞 L →* 𝓞 K :=
RingOfIntegers.restrict_monoidHom
((Algebra.norm K).comp (algebraMap (𝓞 L) L : (𝓞 L) →* L))
fun x => isIntegral_norm K x.2
#align ring_of_integers.norm RingOfIntegers.norm
@[simp] lemma coe_norm [IsSeparable K L] (x : 𝓞 L) :
norm K x = Algebra.norm K (x : L) := rfl
theorem coe_algebraMap_norm [IsSeparable K L] (x : 𝓞 L) :
(algebraMap (𝓞 K) (𝓞 L) (norm K x) : L) = algebraMap K L (Algebra.norm K (x : L)) :=
rfl
#align ring_of_integers.coe_algebra_map_norm RingOfIntegers.coe_algebraMap_norm
theorem algebraMap_norm_algebraMap [IsSeparable K L] (x : 𝓞 K) :
algebraMap _ K (norm K (algebraMap (𝓞 K) (𝓞 L) x)) =
Algebra.norm K (algebraMap K L (algebraMap _ _ x)) := rfl
#align ring_of_integers.coe_norm_algebra_map RingOfIntegers.algebraMap_norm_algebraMap
theorem norm_algebraMap [IsSeparable K L] (x : 𝓞 K) :
norm K (algebraMap (𝓞 K) (𝓞 L) x) = x ^ finrank K L := by
rw [RingOfIntegers.ext_iff, RingOfIntegers.coe_eq_algebraMap,
RingOfIntegers.algebraMap_norm_algebraMap, Algebra.norm_algebraMap,
RingOfIntegers.coe_eq_algebraMap, map_pow]
#align ring_of_integers.norm_algebra_map RingOfIntegers.norm_algebraMap
theorem isUnit_norm_of_isGalois [IsGalois K L] {x : 𝓞 L} : IsUnit (norm K x) ↔ IsUnit x := by
classical
refine ⟨fun hx => ?_, IsUnit.map _⟩
replace hx : IsUnit (algebraMap (𝓞 K) (𝓞 L) <| norm K x) := hx.map (algebraMap (𝓞 K) <| 𝓞 L)
refine @isUnit_of_mul_isUnit_right (𝓞 L) _
⟨(univ \ {AlgEquiv.refl}).prod fun σ : L ≃ₐ[K] L => σ x,
prod_mem fun σ _ => x.2.map (σ : L →+* L).toIntAlgHom⟩ _ ?_
convert hx using 1
ext
convert_to ((univ \ {AlgEquiv.refl}).prod fun σ : L ≃ₐ[K] L => σ x) *
∏ σ ∈ {(AlgEquiv.refl : L ≃ₐ[K] L)}, σ x = _
· rw [prod_singleton, AlgEquiv.coe_refl, _root_.id, RingOfIntegers.coe_eq_algebraMap, map_mul,
RingOfIntegers.map_mk]
· rw [prod_sdiff <| subset_univ _, ← norm_eq_prod_automorphisms, coe_algebraMap_norm]
#align ring_of_integers.is_unit_norm_of_is_galois RingOfIntegers.isUnit_norm_of_isGalois
/-- If `L/K` is a finite Galois extension of fields, then, for all `(x : 𝓞 L)` we have that
`x ∣ algebraMap (𝓞 K) (𝓞 L) (norm K x)`. -/
| Mathlib/NumberTheory/NumberField/Norm.lean | 90 | 99 | theorem dvd_norm [IsGalois K L] (x : 𝓞 L) : x ∣ algebraMap (𝓞 K) (𝓞 L) (norm K x) := by |
classical
have hint :
IsIntegral ℤ (∏ σ ∈ univ.erase (AlgEquiv.refl : L ≃ₐ[K] L), σ x) :=
IsIntegral.prod _ (fun σ _ =>
((RingOfIntegers.isIntegral_coe x).map σ))
refine ⟨⟨_, hint⟩, ?_⟩
ext
rw [coe_algebraMap_norm K x, norm_eq_prod_automorphisms]
simp [← Finset.mul_prod_erase _ _ (mem_univ AlgEquiv.refl)]
|
/-
Copyright (c) 2020 Chris Hughes. All rights reserved.
Released under Apache 2.0 license as described in the file LICENSE.
Authors: Chris Hughes
-/
import Mathlib.Data.Nat.Cast.WithTop
import Mathlib.RingTheory.Prime
import Mathlib.RingTheory.Polynomial.Content
import Mathlib.RingTheory.Ideal.Quotient
#align_import ring_theory.eisenstein_criterion from "leanprover-community/mathlib"@"da420a8c6dd5bdfb85c4ced85c34388f633bc6ff"
/-!
# Eisenstein's criterion
A proof of a slight generalisation of Eisenstein's criterion for the irreducibility of
a polynomial over an integral domain.
-/
open Polynomial Ideal.Quotient
variable {R : Type*} [CommRing R]
namespace Polynomial
open Polynomial
namespace EisensteinCriterionAux
-- Section for auxiliary lemmas used in the proof of `irreducible_of_eisenstein_criterion`
theorem map_eq_C_mul_X_pow_of_forall_coeff_mem {f : R[X]} {P : Ideal R}
(hfP : ∀ n : ℕ, ↑n < f.degree → f.coeff n ∈ P) :
map (mk P) f = C ((mk P) f.leadingCoeff) * X ^ f.natDegree :=
Polynomial.ext fun n => by
by_cases hf0 : f = 0
· simp [hf0]
rcases lt_trichotomy (n : WithBot ℕ) (degree f) with (h | h | h)
· erw [coeff_map, eq_zero_iff_mem.2 (hfP n h), coeff_C_mul, coeff_X_pow, if_neg,
mul_zero]
rintro rfl
exact not_lt_of_ge degree_le_natDegree h
· have : natDegree f = n := natDegree_eq_of_degree_eq_some h.symm
rw [coeff_C_mul, coeff_X_pow, if_pos this.symm, mul_one, leadingCoeff, this, coeff_map]
· rw [coeff_eq_zero_of_degree_lt, coeff_eq_zero_of_degree_lt]
· refine lt_of_le_of_lt (degree_C_mul_X_pow_le _ _) ?_
rwa [← degree_eq_natDegree hf0]
· exact lt_of_le_of_lt (degree_map_le _ _) h
set_option linter.uppercaseLean3 false in
#align polynomial.eisenstein_criterion_aux.map_eq_C_mul_X_pow_of_forall_coeff_mem Polynomial.EisensteinCriterionAux.map_eq_C_mul_X_pow_of_forall_coeff_mem
theorem le_natDegree_of_map_eq_mul_X_pow {n : ℕ} {P : Ideal R} (hP : P.IsPrime) {q : R[X]}
{c : Polynomial (R ⧸ P)} (hq : map (mk P) q = c * X ^ n) (hc0 : c.degree = 0) :
n ≤ q.natDegree :=
Nat.cast_le.1
(calc
↑n = degree (q.map (mk P)) := by
rw [hq, degree_mul, hc0, zero_add, degree_pow, degree_X, nsmul_one]
_ ≤ degree q := degree_map_le _ _
_ ≤ natDegree q := degree_le_natDegree
)
set_option linter.uppercaseLean3 false in
#align polynomial.eisenstein_criterion_aux.le_nat_degree_of_map_eq_mul_X_pow Polynomial.EisensteinCriterionAux.le_natDegree_of_map_eq_mul_X_pow
theorem eval_zero_mem_ideal_of_eq_mul_X_pow {n : ℕ} {P : Ideal R} {q : R[X]}
{c : Polynomial (R ⧸ P)} (hq : map (mk P) q = c * X ^ n) (hn0 : n ≠ 0) : eval 0 q ∈ P := by
rw [← coeff_zero_eq_eval_zero, ← eq_zero_iff_mem, ← coeff_map, hq,
coeff_zero_eq_eval_zero, eval_mul, eval_pow, eval_X, zero_pow hn0, mul_zero]
set_option linter.uppercaseLean3 false in
#align polynomial.eisenstein_criterion_aux.eval_zero_mem_ideal_of_eq_mul_X_pow Polynomial.EisensteinCriterionAux.eval_zero_mem_ideal_of_eq_mul_X_pow
| Mathlib/RingTheory/EisensteinCriterion.lean | 72 | 78 | theorem isUnit_of_natDegree_eq_zero_of_isPrimitive {p q : R[X]}
-- Porting note: stated using `IsPrimitive` which is defeq to old statement.
(hu : IsPrimitive (p * q)) (hpm : p.natDegree = 0) : IsUnit p := by |
rw [eq_C_of_degree_le_zero (natDegree_eq_zero_iff_degree_le_zero.1 hpm), isUnit_C]
refine hu _ ?_
rw [← eq_C_of_degree_le_zero (natDegree_eq_zero_iff_degree_le_zero.1 hpm)]
exact dvd_mul_right _ _
|
/-
Copyright (c) 2023 Yaël Dillies. All rights reserved.
Released under Apache 2.0 license as described in the file LICENSE.
Authors: Yaël Dillies
-/
import Mathlib.Data.Finset.Pointwise
#align_import combinatorics.additive.e_transform from "leanprover-community/mathlib"@"207c92594599a06e7c134f8d00a030a83e6c7259"
/-!
# e-transforms
e-transforms are a family of transformations of pairs of finite sets that aim to reduce the size
of the sumset while keeping some invariant the same. This file defines a few of them, to be used
as internals of other proofs.
## Main declarations
* `Finset.mulDysonETransform`: The Dyson e-transform. Replaces `(s, t)` by
`(s ∪ e • t, t ∩ e⁻¹ • s)`. The additive version preserves `|s ∩ [1, m]| + |t ∩ [1, m - e]|`.
* `Finset.mulETransformLeft`/`Finset.mulETransformRight`: Replace `(s, t)` by
`(s ∩ s • e, t ∪ e⁻¹ • t)` and `(s ∪ s • e, t ∩ e⁻¹ • t)`. Preserve (together) the sum of
the cardinalities (see `Finset.MulETransform.card`). In particular, one of the two transforms
increases the sum of the cardinalities and the other one decreases it. See
`le_or_lt_of_add_le_add` and around.
## TODO
Prove the invariance property of the Dyson e-transform.
-/
open MulOpposite
open Pointwise
variable {α : Type*} [DecidableEq α]
namespace Finset
/-! ### Dyson e-transform -/
section CommGroup
variable [CommGroup α] (e : α) (x : Finset α × Finset α)
/-- The **Dyson e-transform**. Turns `(s, t)` into `(s ∪ e • t, t ∩ e⁻¹ • s)`. This reduces the
product of the two sets. -/
@[to_additive (attr := simps) "The **Dyson e-transform**.
Turns `(s, t)` into `(s ∪ e +ᵥ t, t ∩ -e +ᵥ s)`. This reduces the sum of the two sets."]
def mulDysonETransform : Finset α × Finset α :=
(x.1 ∪ e • x.2, x.2 ∩ e⁻¹ • x.1)
#align finset.mul_dyson_e_transform Finset.mulDysonETransform
#align finset.add_dyson_e_transform Finset.addDysonETransform
@[to_additive]
theorem mulDysonETransform.subset :
(mulDysonETransform e x).1 * (mulDysonETransform e x).2 ⊆ x.1 * x.2 := by
refine union_mul_inter_subset_union.trans (union_subset Subset.rfl ?_)
rw [mul_smul_comm, smul_mul_assoc, inv_smul_smul, mul_comm]
#align finset.mul_dyson_e_transform.subset Finset.mulDysonETransform.subset
#align finset.add_dyson_e_transform.subset Finset.addDysonETransform.subset
@[to_additive]
theorem mulDysonETransform.card :
(mulDysonETransform e x).1.card + (mulDysonETransform e x).2.card = x.1.card + x.2.card := by
dsimp
rw [← card_smul_finset e (_ ∩ _), smul_finset_inter, smul_inv_smul, inter_comm,
card_union_add_card_inter, card_smul_finset]
#align finset.mul_dyson_e_transform.card Finset.mulDysonETransform.card
#align finset.add_dyson_e_transform.card Finset.addDysonETransform.card
@[to_additive (attr := simp)]
theorem mulDysonETransform_idem :
mulDysonETransform e (mulDysonETransform e x) = mulDysonETransform e x := by
ext : 1 <;> dsimp
· rw [smul_finset_inter, smul_inv_smul, inter_comm, union_eq_left]
exact inter_subset_union
· rw [smul_finset_union, inv_smul_smul, union_comm, inter_eq_left]
exact inter_subset_union
#align finset.mul_dyson_e_transform_idem Finset.mulDysonETransform_idem
#align finset.add_dyson_e_transform_idem Finset.addDysonETransform_idem
variable {e x}
@[to_additive]
| Mathlib/Combinatorics/Additive/ETransform.lean | 88 | 92 | theorem mulDysonETransform.smul_finset_snd_subset_fst :
e • (mulDysonETransform e x).2 ⊆ (mulDysonETransform e x).1 := by |
dsimp
rw [smul_finset_inter, smul_inv_smul, inter_comm]
exact inter_subset_union
|
/-
Copyright (c) 2023 Dagur Asgeirsson. All rights reserved.
Released under Apache 2.0 license as described in the file LICENSE.
Authors: Dagur Asgeirsson
-/
import Mathlib.Algebra.Category.ModuleCat.Free
import Mathlib.Topology.Category.Profinite.CofilteredLimit
import Mathlib.Topology.Category.Profinite.Product
import Mathlib.Topology.LocallyConstant.Algebra
import Mathlib.Init.Data.Bool.Lemmas
/-!
# Nöbeling's theorem
This file proves Nöbeling's theorem.
## Main result
* `LocallyConstant.freeOfProfinite`: Nöbeling's theorem.
For `S : Profinite`, the `ℤ`-module `LocallyConstant S ℤ` is free.
## Proof idea
We follow the proof of theorem 5.4 in [scholze2019condensed], in which the idea is to embed `S` in
a product of `I` copies of `Bool` for some sufficiently large `I`, and then to choose a
well-ordering on `I` and use ordinal induction over that well-order. Here we can let `I` be
the set of clopen subsets of `S` since `S` is totally separated.
The above means it suffices to prove the following statement: For a closed subset `C` of `I → Bool`,
the `ℤ`-module `LocallyConstant C ℤ` is free.
For `i : I`, let `e C i : LocallyConstant C ℤ` denote the map `fun f ↦ (if f.val i then 1 else 0)`.
The basis will consist of products `e C iᵣ * ⋯ * e C i₁` with `iᵣ > ⋯ > i₁` which cannot be written
as linear combinations of lexicographically smaller products. We call this set `GoodProducts C`
What is proved by ordinal induction is that this set is linearly independent. The fact that it
spans can be proved directly.
## References
- [scholze2019condensed], Theorem 5.4.
-/
universe u
namespace Profinite
namespace NobelingProof
variable {I : Type u} [LinearOrder I] [IsWellOrder I (·<·)] (C : Set (I → Bool))
open Profinite ContinuousMap CategoryTheory Limits Opposite Submodule
section Projections
/-!
## Projection maps
The purpose of this section is twofold.
Firstly, in the proof that the set `GoodProducts C` spans the whole module `LocallyConstant C ℤ`,
we need to project `C` down to finite discrete subsets and write `C` as a cofiltered limit of those.
Secondly, in the inductive argument, we need to project `C` down to "smaller" sets satisfying the
inductive hypothesis.
In this section we define the relevant projection maps and prove some compatibility results.
### Main definitions
* Let `J : I → Prop`. Then `Proj J : (I → Bool) → (I → Bool)` is the projection mapping everything
that satisfies `J i` to itself, and everything else to `false`.
* The image of `C` under `Proj J` is denoted `π C J` and the corresponding map `C → π C J` is called
`ProjRestrict`. If `J` implies `K` we have a map `ProjRestricts : π C K → π C J`.
* `spanCone_isLimit` establishes that when `C` is compact, it can be written as a limit of its
images under the maps `Proj (· ∈ s)` where `s : Finset I`.
-/
variable (J K L : I → Prop) [∀ i, Decidable (J i)] [∀ i, Decidable (K i)] [∀ i, Decidable (L i)]
/--
The projection mapping everything that satisfies `J i` to itself, and everything else to `false`
-/
def Proj : (I → Bool) → (I → Bool) :=
fun c i ↦ if J i then c i else false
@[simp]
theorem continuous_proj :
Continuous (Proj J : (I → Bool) → (I → Bool)) := by
dsimp (config := { unfoldPartialApp := true }) [Proj]
apply continuous_pi
intro i
split
· apply continuous_apply
· apply continuous_const
/-- The image of `Proj π J` -/
def π : Set (I → Bool) := (Proj J) '' C
/-- The restriction of `Proj π J` to a subset, mapping to its image. -/
@[simps!]
def ProjRestrict : C → π C J :=
Set.MapsTo.restrict (Proj J) _ _ (Set.mapsTo_image _ _)
@[simp]
theorem continuous_projRestrict : Continuous (ProjRestrict C J) :=
Continuous.restrict _ (continuous_proj _)
theorem proj_eq_self {x : I → Bool} (h : ∀ i, x i ≠ false → J i) : Proj J x = x := by
ext i
simp only [Proj, ite_eq_left_iff]
contrapose!
simpa only [ne_comm] using h i
theorem proj_prop_eq_self (hh : ∀ i x, x ∈ C → x i ≠ false → J i) : π C J = C := by
ext x
refine ⟨fun ⟨y, hy, h⟩ ↦ ?_, fun h ↦ ⟨x, h, ?_⟩⟩
· rwa [← h, proj_eq_self]; exact (hh · y hy)
· rw [proj_eq_self]; exact (hh · x h)
theorem proj_comp_of_subset (h : ∀ i, J i → K i) : (Proj J ∘ Proj K) =
(Proj J : (I → Bool) → (I → Bool)) := by
ext x i; dsimp [Proj]; aesop
| Mathlib/Topology/Category/Profinite/Nobeling.lean | 129 | 139 | theorem proj_eq_of_subset (h : ∀ i, J i → K i) : π (π C K) J = π C J := by |
ext x
refine ⟨fun h ↦ ?_, fun h ↦ ?_⟩
· obtain ⟨y, ⟨z, hz, rfl⟩, rfl⟩ := h
refine ⟨z, hz, (?_ : _ = (Proj J ∘ Proj K) z)⟩
rw [proj_comp_of_subset J K h]
· obtain ⟨y, hy, rfl⟩ := h
dsimp [π]
rw [← Set.image_comp]
refine ⟨y, hy, ?_⟩
rw [proj_comp_of_subset J K h]
|
/-
Copyright (c) 2018 Mario Carneiro. All rights reserved.
Released under Apache 2.0 license as described in the file LICENSE.
Authors: Mario Carneiro, Kenny Lau, Yury Kudryashov
-/
import Mathlib.Logic.Relation
import Mathlib.Data.List.Forall2
import Mathlib.Data.List.Lex
import Mathlib.Data.List.Infix
#align_import data.list.chain from "leanprover-community/mathlib"@"dd71334db81d0bd444af1ee339a29298bef40734"
/-!
# Relation chain
This file provides basic results about `List.Chain` (definition in `Data.List.Defs`).
A list `[a₂, ..., aₙ]` is a `Chain` starting at `a₁` with respect to the relation `r` if `r a₁ a₂`
and `r a₂ a₃` and ... and `r aₙ₋₁ aₙ`. We write it `Chain r a₁ [a₂, ..., aₙ]`.
A graph-specialized version is in development and will hopefully be added under `combinatorics.`
sometime soon.
-/
-- Make sure we haven't imported `Data.Nat.Order.Basic`
assert_not_exists OrderedSub
universe u v
open Nat
namespace List
variable {α : Type u} {β : Type v} {R r : α → α → Prop} {l l₁ l₂ : List α} {a b : α}
mk_iff_of_inductive_prop List.Chain List.chain_iff
#align list.chain_iff List.chain_iff
#align list.chain.nil List.Chain.nil
#align list.chain.cons List.Chain.cons
#align list.rel_of_chain_cons List.rel_of_chain_cons
#align list.chain_of_chain_cons List.chain_of_chain_cons
#align list.chain.imp' List.Chain.imp'
#align list.chain.imp List.Chain.imp
theorem Chain.iff {S : α → α → Prop} (H : ∀ a b, R a b ↔ S a b) {a : α} {l : List α} :
Chain R a l ↔ Chain S a l :=
⟨Chain.imp fun a b => (H a b).1, Chain.imp fun a b => (H a b).2⟩
#align list.chain.iff List.Chain.iff
theorem Chain.iff_mem {a : α} {l : List α} :
Chain R a l ↔ Chain (fun x y => x ∈ a :: l ∧ y ∈ l ∧ R x y) a l :=
⟨fun p => by
induction' p with _ a b l r _ IH <;> constructor <;>
[exact ⟨mem_cons_self _ _, mem_cons_self _ _, r⟩;
exact IH.imp fun a b ⟨am, bm, h⟩ => ⟨mem_cons_of_mem _ am, mem_cons_of_mem _ bm, h⟩],
Chain.imp fun a b h => h.2.2⟩
#align list.chain.iff_mem List.Chain.iff_mem
theorem chain_singleton {a b : α} : Chain R a [b] ↔ R a b := by
simp only [chain_cons, Chain.nil, and_true_iff]
#align list.chain_singleton List.chain_singleton
theorem chain_split {a b : α} {l₁ l₂ : List α} :
Chain R a (l₁ ++ b :: l₂) ↔ Chain R a (l₁ ++ [b]) ∧ Chain R b l₂ := by
induction' l₁ with x l₁ IH generalizing a <;>
simp only [*, nil_append, cons_append, Chain.nil, chain_cons, and_true_iff, and_assoc]
#align list.chain_split List.chain_split
@[simp]
theorem chain_append_cons_cons {a b c : α} {l₁ l₂ : List α} :
Chain R a (l₁ ++ b :: c :: l₂) ↔ Chain R a (l₁ ++ [b]) ∧ R b c ∧ Chain R c l₂ := by
rw [chain_split, chain_cons]
#align list.chain_append_cons_cons List.chain_append_cons_cons
theorem chain_iff_forall₂ :
∀ {a : α} {l : List α}, Chain R a l ↔ l = [] ∨ Forall₂ R (a :: dropLast l) l
| a, [] => by simp
| a, b :: l => by
by_cases h : l = [] <;>
simp [@chain_iff_forall₂ b l, dropLast, *]
#align list.chain_iff_forall₂ List.chain_iff_forall₂
| Mathlib/Data/List/Chain.lean | 82 | 83 | theorem chain_append_singleton_iff_forall₂ :
Chain R a (l ++ [b]) ↔ Forall₂ R (a :: l) (l ++ [b]) := by | simp [chain_iff_forall₂]
|
/-
Copyright (c) 2020 Scott Morrison. All rights reserved.
Released under Apache 2.0 license as described in the file LICENSE.
Authors: Scott Morrison
-/
import Mathlib.CategoryTheory.Monoidal.Braided.Basic
import Mathlib.CategoryTheory.Monoidal.Discrete
import Mathlib.CategoryTheory.Monoidal.CoherenceLemmas
import Mathlib.CategoryTheory.Limits.Shapes.Terminal
import Mathlib.Algebra.PUnitInstances
#align_import category_theory.monoidal.Mon_ from "leanprover-community/mathlib"@"a836c6dba9bd1ee2a0cdc9af0006a596f243031c"
/-!
# The category of monoids in a monoidal category.
We define monoids in a monoidal category `C` and show that the category of monoids is equivalent to
the category of lax monoidal functors from the unit monoidal category to `C`. We also show that if
`C` is braided, then the category of monoids is naturally monoidal.
-/
set_option linter.uppercaseLean3 false
universe v₁ v₂ u₁ u₂ u
open CategoryTheory MonoidalCategory
variable (C : Type u₁) [Category.{v₁} C] [MonoidalCategory.{v₁} C]
/-- A monoid object internal to a monoidal category.
When the monoidal category is preadditive, this is also sometimes called an "algebra object".
-/
structure Mon_ where
X : C
one : 𝟙_ C ⟶ X
mul : X ⊗ X ⟶ X
one_mul : (one ▷ X) ≫ mul = (λ_ X).hom := by aesop_cat
mul_one : (X ◁ one) ≫ mul = (ρ_ X).hom := by aesop_cat
-- Obviously there is some flexibility stating this axiom.
-- This one has left- and right-hand sides matching the statement of `Monoid.mul_assoc`,
-- and chooses to place the associator on the right-hand side.
-- The heuristic is that unitors and associators "don't have much weight".
mul_assoc : (mul ▷ X) ≫ mul = (α_ X X X).hom ≫ (X ◁ mul) ≫ mul := by aesop_cat
#align Mon_ Mon_
attribute [reassoc] Mon_.one_mul Mon_.mul_one
attribute [simp] Mon_.one_mul Mon_.mul_one
-- We prove a more general `@[simp]` lemma below.
attribute [reassoc (attr := simp)] Mon_.mul_assoc
namespace Mon_
/-- The trivial monoid object. We later show this is initial in `Mon_ C`.
-/
@[simps]
def trivial : Mon_ C where
X := 𝟙_ C
one := 𝟙 _
mul := (λ_ _).hom
mul_assoc := by coherence
mul_one := by coherence
#align Mon_.trivial Mon_.trivial
instance : Inhabited (Mon_ C) :=
⟨trivial C⟩
variable {C}
variable {M : Mon_ C}
@[simp]
theorem one_mul_hom {Z : C} (f : Z ⟶ M.X) : (M.one ⊗ f) ≫ M.mul = (λ_ Z).hom ≫ f := by
rw [tensorHom_def'_assoc, M.one_mul, leftUnitor_naturality]
#align Mon_.one_mul_hom Mon_.one_mul_hom
@[simp]
theorem mul_one_hom {Z : C} (f : Z ⟶ M.X) : (f ⊗ M.one) ≫ M.mul = (ρ_ Z).hom ≫ f := by
rw [tensorHom_def_assoc, M.mul_one, rightUnitor_naturality]
#align Mon_.mul_one_hom Mon_.mul_one_hom
| Mathlib/CategoryTheory/Monoidal/Mon_.lean | 84 | 85 | theorem assoc_flip :
(M.X ◁ M.mul) ≫ M.mul = (α_ M.X M.X M.X).inv ≫ (M.mul ▷ M.X) ≫ M.mul := by | simp
|
/-
Copyright (c) 2021 Scott Morrison. All rights reserved.
Released under Apache 2.0 license as described in the file LICENSE.
Authors: Scott Morrison
-/
import Mathlib.CategoryTheory.Subobject.Limits
#align_import algebra.homology.image_to_kernel from "leanprover-community/mathlib"@"618ea3d5c99240cd7000d8376924906a148bf9ff"
/-!
# Image-to-kernel comparison maps
Whenever `f : A ⟶ B` and `g : B ⟶ C` satisfy `w : f ≫ g = 0`,
we have `image_le_kernel f g w : imageSubobject f ≤ kernelSubobject g`
(assuming the appropriate images and kernels exist).
`imageToKernel f g w` is the corresponding morphism between objects in `C`.
We define `homology' f g w` of such a pair as the cokernel of `imageToKernel f g w`.
Note: As part of the transition to the new homology API, `homology` is temporarily
renamed `homology'`. It is planned that this definition shall be removed and replaced by
`ShortComplex.homology`.
-/
universe v u w
open CategoryTheory CategoryTheory.Limits
variable {ι : Type*}
variable {V : Type u} [Category.{v} V] [HasZeroMorphisms V]
open scoped Classical
noncomputable section
section
variable {A B C : V} (f : A ⟶ B) [HasImage f] (g : B ⟶ C) [HasKernel g]
theorem image_le_kernel (w : f ≫ g = 0) : imageSubobject f ≤ kernelSubobject g :=
imageSubobject_le_mk _ _ (kernel.lift _ _ w) (by simp)
#align image_le_kernel image_le_kernel
/-- The canonical morphism `imageSubobject f ⟶ kernelSubobject g` when `f ≫ g = 0`.
-/
def imageToKernel (w : f ≫ g = 0) : (imageSubobject f : V) ⟶ (kernelSubobject g : V) :=
Subobject.ofLE _ _ (image_le_kernel _ _ w)
#align image_to_kernel imageToKernel
instance (w : f ≫ g = 0) : Mono (imageToKernel f g w) := by
dsimp only [imageToKernel]
infer_instance
/-- Prefer `imageToKernel`. -/
@[simp]
theorem subobject_ofLE_as_imageToKernel (w : f ≫ g = 0) (h) :
Subobject.ofLE (imageSubobject f) (kernelSubobject g) h = imageToKernel f g w :=
rfl
#align subobject_of_le_as_image_to_kernel subobject_ofLE_as_imageToKernel
attribute [local instance] ConcreteCategory.instFunLike
-- Porting note: removed elementwise attribute which does not seem to be helpful here
-- a more suitable lemma is added below
@[reassoc (attr := simp)]
theorem imageToKernel_arrow (w : f ≫ g = 0) :
imageToKernel f g w ≫ (kernelSubobject g).arrow = (imageSubobject f).arrow := by
simp [imageToKernel]
#align image_to_kernel_arrow imageToKernel_arrow
@[simp]
lemma imageToKernel_arrow_apply [ConcreteCategory V] (w : f ≫ g = 0)
(x : (forget V).obj (Subobject.underlying.obj (imageSubobject f))) :
(kernelSubobject g).arrow (imageToKernel f g w x) =
(imageSubobject f).arrow x := by
rw [← comp_apply, imageToKernel_arrow]
-- This is less useful as a `simp` lemma than it initially appears,
-- as it "loses" the information the morphism factors through the image.
theorem factorThruImageSubobject_comp_imageToKernel (w : f ≫ g = 0) :
factorThruImageSubobject f ≫ imageToKernel f g w = factorThruKernelSubobject g f w := by
ext
simp
#align factor_thru_image_subobject_comp_image_to_kernel factorThruImageSubobject_comp_imageToKernel
end
section
variable {A B C : V} (f : A ⟶ B) (g : B ⟶ C)
@[simp]
theorem imageToKernel_zero_left [HasKernels V] [HasZeroObject V] {w} :
imageToKernel (0 : A ⟶ B) g w = 0 := by
ext
simp
#align image_to_kernel_zero_left imageToKernel_zero_left
theorem imageToKernel_zero_right [HasImages V] {w} :
imageToKernel f (0 : B ⟶ C) w =
(imageSubobject f).arrow ≫ inv (kernelSubobject (0 : B ⟶ C)).arrow := by
ext
simp
#align image_to_kernel_zero_right imageToKernel_zero_right
section
variable [HasKernels V] [HasImages V]
theorem imageToKernel_comp_right {D : V} (h : C ⟶ D) (w : f ≫ g = 0) :
imageToKernel f (g ≫ h) (by simp [reassoc_of% w]) =
imageToKernel f g w ≫ Subobject.ofLE _ _ (kernelSubobject_comp_le g h) := by
ext
simp
#align image_to_kernel_comp_right imageToKernel_comp_right
theorem imageToKernel_comp_left {Z : V} (h : Z ⟶ A) (w : f ≫ g = 0) :
imageToKernel (h ≫ f) g (by simp [w]) =
Subobject.ofLE _ _ (imageSubobject_comp_le h f) ≫ imageToKernel f g w := by
ext
simp
#align image_to_kernel_comp_left imageToKernel_comp_left
@[simp]
| Mathlib/Algebra/Homology/ImageToKernel.lean | 127 | 132 | theorem imageToKernel_comp_mono {D : V} (h : C ⟶ D) [Mono h] (w) :
imageToKernel f (g ≫ h) w =
imageToKernel f g ((cancel_mono h).mp (by simpa using w : (f ≫ g) ≫ h = 0 ≫ h)) ≫
(Subobject.isoOfEq _ _ (kernelSubobject_comp_mono g h)).inv := by |
ext
simp
|
/-
Copyright (c) 2023 Luke Mantle. All rights reserved.
Released under Apache 2.0 license as described in the file LICENSE.
Authors: Luke Mantle
-/
import Mathlib.Algebra.Order.Ring.Abs
import Mathlib.Algebra.Polynomial.Derivative
import Mathlib.Data.Nat.Factorial.DoubleFactorial
#align_import ring_theory.polynomial.hermite.basic from "leanprover-community/mathlib"@"938d3db9c278f8a52c0f964a405806f0f2b09b74"
/-!
# Hermite polynomials
This file defines `Polynomial.hermite n`, the `n`th probabilists' Hermite polynomial.
## Main definitions
* `Polynomial.hermite n`: the `n`th probabilists' Hermite polynomial,
defined recursively as a `Polynomial ℤ`
## Results
* `Polynomial.hermite_succ`: the recursion `hermite (n+1) = (x - d/dx) (hermite n)`
* `Polynomial.coeff_hermite_explicit`: a closed formula for (nonvanishing) coefficients in terms
of binomial coefficients and double factorials.
* `Polynomial.coeff_hermite_of_odd_add`: for `n`,`k` where `n+k` is odd, `(hermite n).coeff k` is
zero.
* `Polynomial.coeff_hermite_of_even_add`: a closed formula for `(hermite n).coeff k` when `n+k` is
even, equivalent to `Polynomial.coeff_hermite_explicit`.
* `Polynomial.monic_hermite`: for all `n`, `hermite n` is monic.
* `Polynomial.degree_hermite`: for all `n`, `hermite n` has degree `n`.
## References
* [Hermite Polynomials](https://en.wikipedia.org/wiki/Hermite_polynomials)
-/
noncomputable section
open Polynomial
namespace Polynomial
/-- the probabilists' Hermite polynomials. -/
noncomputable def hermite : ℕ → Polynomial ℤ
| 0 => 1
| n + 1 => X * hermite n - derivative (hermite n)
#align polynomial.hermite Polynomial.hermite
/-- The recursion `hermite (n+1) = (x - d/dx) (hermite n)` -/
@[simp]
theorem hermite_succ (n : ℕ) : hermite (n + 1) = X * hermite n - derivative (hermite n) := by
rw [hermite]
#align polynomial.hermite_succ Polynomial.hermite_succ
theorem hermite_eq_iterate (n : ℕ) : hermite n = (fun p => X * p - derivative p)^[n] 1 := by
induction' n with n ih
· rfl
· rw [Function.iterate_succ_apply', ← ih, hermite_succ]
#align polynomial.hermite_eq_iterate Polynomial.hermite_eq_iterate
@[simp]
theorem hermite_zero : hermite 0 = C 1 :=
rfl
#align polynomial.hermite_zero Polynomial.hermite_zero
-- Porting note (#10618): There was initially @[simp] on this line but it was removed
-- because simp can prove this theorem
theorem hermite_one : hermite 1 = X := by
rw [hermite_succ, hermite_zero]
simp only [map_one, mul_one, derivative_one, sub_zero]
#align polynomial.hermite_one Polynomial.hermite_one
/-! ### Lemmas about `Polynomial.coeff` -/
section coeff
theorem coeff_hermite_succ_zero (n : ℕ) : coeff (hermite (n + 1)) 0 = -coeff (hermite n) 1 := by
simp [coeff_derivative]
#align polynomial.coeff_hermite_succ_zero Polynomial.coeff_hermite_succ_zero
theorem coeff_hermite_succ_succ (n k : ℕ) : coeff (hermite (n + 1)) (k + 1) =
coeff (hermite n) k - (k + 2) * coeff (hermite n) (k + 2) := by
rw [hermite_succ, coeff_sub, coeff_X_mul, coeff_derivative, mul_comm]
norm_cast
#align polynomial.coeff_hermite_succ_succ Polynomial.coeff_hermite_succ_succ
theorem coeff_hermite_of_lt {n k : ℕ} (hnk : n < k) : coeff (hermite n) k = 0 := by
obtain ⟨k, rfl⟩ := Nat.exists_eq_add_of_lt hnk
clear hnk
induction' n with n ih generalizing k
· apply coeff_C
· have : n + k + 1 + 2 = n + (k + 2) + 1 := by ring
rw [coeff_hermite_succ_succ, add_right_comm, this, ih k, ih (k + 2),
mul_zero, sub_zero]
#align polynomial.coeff_hermite_of_lt Polynomial.coeff_hermite_of_lt
@[simp]
| Mathlib/RingTheory/Polynomial/Hermite/Basic.lean | 103 | 107 | theorem coeff_hermite_self (n : ℕ) : coeff (hermite n) n = 1 := by |
induction' n with n ih
· apply coeff_C
· rw [coeff_hermite_succ_succ, ih, coeff_hermite_of_lt, mul_zero, sub_zero]
simp
|
/-
Copyright (c) 2023 Yury Kudryashov. All rights reserved.
Released under Apache 2.0 license as described in the file LICENSE.
Authors: Yury Kudryashov
-/
import Mathlib.Analysis.Convex.Gauge
import Mathlib.Analysis.Convex.Normed
/-!
# "Gauge rescale" homeomorphism between convex sets
Given two convex von Neumann bounded neighbourhoods of the origin
in a real topological vector space,
we construct a homeomorphism `gaugeRescaleHomeomorph`
that sends the interior, the closure, and the frontier of one set
to the interior, the closure, and the frontier of the other set.
-/
open Metric Bornology Filter Set
open scoped NNReal Topology Pointwise
noncomputable section
section Module
variable {E : Type*} [AddCommGroup E] [Module ℝ E]
/-- The gauge rescale map `gaugeRescale s t` sends each point `x` to the point `y` on the same ray
that has the same gauge w.r.t. `t` as `x` has w.r.t. `s`.
The characteristic property is satisfied if `gauge t x ≠ 0`, see `gauge_gaugeRescale'`.
In particular, it is satisfied for all `x`,
provided that `t` is absorbent and von Neumann bounded. -/
def gaugeRescale (s t : Set E) (x : E) : E := (gauge s x / gauge t x) • x
theorem gaugeRescale_def (s t : Set E) (x : E) :
gaugeRescale s t x = (gauge s x / gauge t x) • x :=
rfl
@[simp] theorem gaugeRescale_zero (s t : Set E) : gaugeRescale s t 0 = 0 := smul_zero _
theorem gaugeRescale_smul (s t : Set E) {c : ℝ} (hc : 0 ≤ c) (x : E) :
gaugeRescale s t (c • x) = c • gaugeRescale s t x := by
simp only [gaugeRescale, gauge_smul_of_nonneg hc, smul_smul, smul_eq_mul]
rw [mul_div_mul_comm, mul_right_comm, div_self_mul_self]
variable [TopologicalSpace E] [T1Space E]
| Mathlib/Analysis/Convex/GaugeRescale.lean | 48 | 52 | theorem gaugeRescale_self_apply {s : Set E} (hsa : Absorbent ℝ s) (hsb : IsVonNBounded ℝ s)
(x : E) : gaugeRescale s s x = x := by |
rcases eq_or_ne x 0 with rfl | hx; · simp
rw [gaugeRescale, div_self, one_smul]
exact ((gauge_pos hsa hsb).2 hx).ne'
|
/-
Copyright (c) 2018 Sébastien Gouëzel. All rights reserved.
Released under Apache 2.0 license as described in the file LICENSE.
Authors: Sébastien Gouëzel
-/
import Mathlib.Order.ConditionallyCompleteLattice.Basic
import Mathlib.Data.Set.Finite
#align_import order.conditionally_complete_lattice.finset from "leanprover-community/mathlib"@"2445c98ae4b87eabebdde552593519b9b6dc350c"
/-!
# Conditionally complete lattices and finite sets.
-/
open Set
variable {ι α β γ : Type*}
section ConditionallyCompleteLinearOrder
variable [ConditionallyCompleteLinearOrder α] {s t : Set α} {a b : α}
theorem Finset.Nonempty.csSup_eq_max' {s : Finset α} (h : s.Nonempty) : sSup ↑s = s.max' h :=
eq_of_forall_ge_iff fun _ => (csSup_le_iff s.bddAbove h.to_set).trans (s.max'_le_iff h).symm
#align finset.nonempty.cSup_eq_max' Finset.Nonempty.csSup_eq_max'
theorem Finset.Nonempty.csInf_eq_min' {s : Finset α} (h : s.Nonempty) : sInf ↑s = s.min' h :=
@Finset.Nonempty.csSup_eq_max' αᵒᵈ _ s h
#align finset.nonempty.cInf_eq_min' Finset.Nonempty.csInf_eq_min'
| Mathlib/Order/ConditionallyCompleteLattice/Finset.lean | 33 | 35 | theorem Finset.Nonempty.csSup_mem {s : Finset α} (h : s.Nonempty) : sSup (s : Set α) ∈ s := by |
rw [h.csSup_eq_max']
exact s.max'_mem _
|
/-
Copyright (c) 2017 Mario Carneiro. All rights reserved.
Released under Apache 2.0 license as described in the file LICENSE.
Authors: Mario Carneiro
-/
import Mathlib.Data.Nat.Lattice
import Mathlib.Logic.Denumerable
import Mathlib.Logic.Function.Iterate
import Mathlib.Order.Hom.Basic
import Mathlib.Data.Set.Subsingleton
#align_import order.order_iso_nat from "leanprover-community/mathlib"@"210657c4ea4a4a7b234392f70a3a2a83346dfa90"
/-!
# Relation embeddings from the naturals
This file allows translation from monotone functions `ℕ → α` to order embeddings `ℕ ↪ α` and
defines the limit value of an eventually-constant sequence.
## Main declarations
* `natLT`/`natGT`: Make an order embedding `Nat ↪ α` from
an increasing/decreasing function `Nat → α`.
* `monotonicSequenceLimit`: The limit of an eventually-constant monotone sequence `Nat →o α`.
* `monotonicSequenceLimitIndex`: The index of the first occurrence of `monotonicSequenceLimit`
in the sequence.
-/
variable {α : Type*}
namespace RelEmbedding
variable {r : α → α → Prop} [IsStrictOrder α r]
/-- If `f` is a strictly `r`-increasing sequence, then this returns `f` as an order embedding. -/
def natLT (f : ℕ → α) (H : ∀ n : ℕ, r (f n) (f (n + 1))) : ((· < ·) : ℕ → ℕ → Prop) ↪r r :=
ofMonotone f <| Nat.rel_of_forall_rel_succ_of_lt r H
#align rel_embedding.nat_lt RelEmbedding.natLT
@[simp]
theorem coe_natLT {f : ℕ → α} {H : ∀ n : ℕ, r (f n) (f (n + 1))} : ⇑(natLT f H) = f :=
rfl
#align rel_embedding.coe_nat_lt RelEmbedding.coe_natLT
/-- If `f` is a strictly `r`-decreasing sequence, then this returns `f` as an order embedding. -/
def natGT (f : ℕ → α) (H : ∀ n : ℕ, r (f (n + 1)) (f n)) : ((· > ·) : ℕ → ℕ → Prop) ↪r r :=
haveI := IsStrictOrder.swap r
RelEmbedding.swap (natLT f H)
#align rel_embedding.nat_gt RelEmbedding.natGT
@[simp]
theorem coe_natGT {f : ℕ → α} {H : ∀ n : ℕ, r (f (n + 1)) (f n)} : ⇑(natGT f H) = f :=
rfl
#align rel_embedding.coe_nat_gt RelEmbedding.coe_natGT
| Mathlib/Order/OrderIsoNat.lean | 58 | 62 | theorem exists_not_acc_lt_of_not_acc {a : α} {r} (h : ¬Acc r a) : ∃ b, ¬Acc r b ∧ r b a := by |
contrapose! h
refine ⟨_, fun b hr => ?_⟩
by_contra hb
exact h b hb hr
|
/-
Copyright (c) 2017 Johannes Hölzl. All rights reserved.
Released under Apache 2.0 license as described in the file LICENSE.
Authors: Johannes Hölzl
-/
import Mathlib.Init.Control.Combinators
import Mathlib.Init.Function
import Mathlib.Tactic.CasesM
import Mathlib.Tactic.Attr.Core
#align_import control.basic from "leanprover-community/mathlib"@"48fb5b5280e7c81672afc9524185ae994553ebf4"
/-!
Extends the theory on functors, applicatives and monads.
-/
universe u v w
variable {α β γ : Type u}
section Functor
variable {f : Type u → Type v} [Functor f] [LawfulFunctor f]
@[functor_norm]
theorem Functor.map_map (m : α → β) (g : β → γ) (x : f α) : g <$> m <$> x = (g ∘ m) <$> x :=
(comp_map _ _ _).symm
#align functor.map_map Functor.map_mapₓ
-- order of implicits
#align id_map' id_map'ₓ
-- order of implicits
end Functor
section Applicative
variable {F : Type u → Type v} [Applicative F]
/-- A generalization of `List.zipWith` which combines list elements with an `Applicative`. -/
def zipWithM {α₁ α₂ φ : Type u} (f : α₁ → α₂ → F φ) : ∀ (_ : List α₁) (_ : List α₂), F (List φ)
| x :: xs, y :: ys => (· :: ·) <$> f x y <*> zipWithM f xs ys
| _, _ => pure []
#align mzip_with zipWithM
/-- Like `zipWithM` but evaluates the result as it traverses the lists using `*>`. -/
def zipWithM' (f : α → β → F γ) : List α → List β → F PUnit
| x :: xs, y :: ys => f x y *> zipWithM' f xs ys
| [], _ => pure PUnit.unit
| _, [] => pure PUnit.unit
#align mzip_with' zipWithM'
variable [LawfulApplicative F]
@[simp]
theorem pure_id'_seq (x : F α) : (pure fun x => x) <*> x = x :=
pure_id_seq x
#align pure_id'_seq pure_id'_seq
@[functor_norm]
theorem seq_map_assoc (x : F (α → β)) (f : γ → α) (y : F γ) :
x <*> f <$> y = (· ∘ f) <$> x <*> y := by
simp only [← pure_seq]
simp only [seq_assoc, Function.comp, seq_pure, ← comp_map]
simp [pure_seq]
#align seq_map_assoc seq_map_assoc
@[functor_norm]
theorem map_seq (f : β → γ) (x : F (α → β)) (y : F α) :
f <$> (x <*> y) = (f ∘ ·) <$> x <*> y := by
simp only [← pure_seq]; simp [seq_assoc]
#align map_seq map_seq
end Applicative
section Monad
variable {m : Type u → Type v} [Monad m] [LawfulMonad m]
open List
#align list.mpartition List.partitionM
| Mathlib/Control/Basic.lean | 83 | 85 | theorem map_bind (x : m α) {g : α → m β} {f : β → γ} :
f <$> (x >>= g) = x >>= fun a => f <$> g a := by |
rw [← bind_pure_comp, bind_assoc]; simp [bind_pure_comp]
|
/-
Copyright (c) 2020 Johan Commelin. All rights reserved.
Released under Apache 2.0 license as described in the file LICENSE.
Authors: Johan Commelin
-/
import Mathlib.Algebra.Group.Units.Hom
import Mathlib.Algebra.GroupWithZero.Commute
import Mathlib.Algebra.GroupWithZero.Hom
import Mathlib.GroupTheory.GroupAction.Units
#align_import algebra.group_with_zero.units.lemmas from "leanprover-community/mathlib"@"dc6c365e751e34d100e80fe6e314c3c3e0fd2988"
/-!
# Further lemmas about units in a `MonoidWithZero` or a `GroupWithZero`.
-/
assert_not_exists DenselyOrdered
variable {α M₀ G₀ M₀' G₀' F F' : Type*}
variable [MonoidWithZero M₀]
namespace Commute
variable [GroupWithZero G₀] {a b c d : G₀}
/-- The `MonoidWithZero` version of `div_eq_div_iff_mul_eq_mul`. -/
protected lemma div_eq_div_iff (hbd : Commute b d) (hb : b ≠ 0) (hd : d ≠ 0) :
a / b = c / d ↔ a * d = c * b := hbd.div_eq_div_iff_of_isUnit hb.isUnit hd.isUnit
end Commute
section MonoidWithZero
variable [GroupWithZero G₀] [Nontrivial M₀] [MonoidWithZero M₀'] [FunLike F G₀ M₀]
[MonoidWithZeroHomClass F G₀ M₀] [FunLike F' G₀ M₀'] [MonoidWithZeroHomClass F' G₀ M₀']
(f : F) {a : G₀}
theorem map_ne_zero : f a ≠ 0 ↔ a ≠ 0 :=
⟨fun hfa ha => hfa <| ha.symm ▸ map_zero f, fun ha => ((IsUnit.mk0 a ha).map f).ne_zero⟩
#align map_ne_zero map_ne_zero
@[simp]
theorem map_eq_zero : f a = 0 ↔ a = 0 :=
not_iff_not.1 (map_ne_zero f)
#align map_eq_zero map_eq_zero
| Mathlib/Algebra/GroupWithZero/Units/Lemmas.lean | 49 | 52 | theorem eq_on_inv₀ (f g : F') (h : f a = g a) : f a⁻¹ = g a⁻¹ := by |
rcases eq_or_ne a 0 with (rfl | ha)
· rw [inv_zero, map_zero, map_zero]
· exact (IsUnit.mk0 a ha).eq_on_inv f g h
|
/-
Copyright (c) 2022 Andrew Yang. All rights reserved.
Released under Apache 2.0 license as described in the file LICENSE.
Authors: Andrew Yang, Joël Riou
-/
import Mathlib.CategoryTheory.Sites.Subsheaf
import Mathlib.CategoryTheory.Sites.CompatibleSheafification
import Mathlib.CategoryTheory.Sites.LocallyInjective
#align_import category_theory.sites.surjective from "leanprover-community/mathlib"@"70fd9563a21e7b963887c9360bd29b2393e6225a"
/-!
# Locally surjective morphisms
## Main definitions
- `IsLocallySurjective` : A morphism of presheaves valued in a concrete category is locally
surjective with respect to a Grothendieck topology if every section in the target is locally
in the set-theoretic image, i.e. the image sheaf coincides with the target.
## Main results
- `Presheaf.isLocallySurjective_toSheafify`: `toSheafify` is locally surjective.
- `Sheaf.isLocallySurjective_iff_epi`: a morphism of sheaves of types is locally
surjective iff it is epi
-/
universe v u w v' u' w'
open Opposite CategoryTheory CategoryTheory.GrothendieckTopology
namespace CategoryTheory
variable {C : Type u} [Category.{v} C] (J : GrothendieckTopology C)
attribute [local instance] ConcreteCategory.hasCoeToSort ConcreteCategory.instFunLike
variable {A : Type u'} [Category.{v'} A] [ConcreteCategory.{w'} A]
namespace Presheaf
/-- Given `f : F ⟶ G`, a morphism between presieves, and `s : G.obj (op U)`, this is the sieve
of `U` consisting of the `i : V ⟶ U` such that `s` restricted along `i` is in the image of `f`. -/
@[simps (config := .lemmasOnly)]
def imageSieve {F G : Cᵒᵖ ⥤ A} (f : F ⟶ G) {U : C} (s : G.obj (op U)) : Sieve U where
arrows V i := ∃ t : F.obj (op V), f.app _ t = G.map i.op s
downward_closed := by
rintro V W i ⟨t, ht⟩ j
refine ⟨F.map j.op t, ?_⟩
rw [op_comp, G.map_comp, comp_apply, ← ht, elementwise_of% f.naturality]
#align category_theory.image_sieve CategoryTheory.Presheaf.imageSieve
theorem imageSieve_eq_sieveOfSection {F G : Cᵒᵖ ⥤ A} (f : F ⟶ G) {U : C} (s : G.obj (op U)) :
imageSieve f s = (imagePresheaf (whiskerRight f (forget A))).sieveOfSection s :=
rfl
#align category_theory.image_sieve_eq_sieve_of_section CategoryTheory.Presheaf.imageSieve_eq_sieveOfSection
theorem imageSieve_whisker_forget {F G : Cᵒᵖ ⥤ A} (f : F ⟶ G) {U : C} (s : G.obj (op U)) :
imageSieve (whiskerRight f (forget A)) s = imageSieve f s :=
rfl
#align category_theory.image_sieve_whisker_forget CategoryTheory.Presheaf.imageSieve_whisker_forget
theorem imageSieve_app {F G : Cᵒᵖ ⥤ A} (f : F ⟶ G) {U : C} (s : F.obj (op U)) :
imageSieve f (f.app _ s) = ⊤ := by
ext V i
simp only [Sieve.top_apply, iff_true_iff, imageSieve_apply]
have := elementwise_of% (f.naturality i.op)
exact ⟨F.map i.op s, this s⟩
#align category_theory.image_sieve_app CategoryTheory.Presheaf.imageSieve_app
/-- If a morphism `g : V ⟶ U.unop` belongs to the sieve `imageSieve f s g`, then
this is choice of a preimage of `G.map g.op s` in `F.obj (op V)`, see
`app_localPreimage`.-/
noncomputable def localPreimage {F G : Cᵒᵖ ⥤ A} (f : F ⟶ G) {U : Cᵒᵖ} (s : G.obj U)
{V : C} (g : V ⟶ U.unop) (hg : imageSieve f s g) :
F.obj (op V) :=
hg.choose
@[simp]
lemma app_localPreimage {F G : Cᵒᵖ ⥤ A} (f : F ⟶ G) {U : Cᵒᵖ} (s : G.obj U)
{V : C} (g : V ⟶ U.unop) (hg : imageSieve f s g) :
f.app _ (localPreimage f s g hg) = G.map g.op s :=
hg.choose_spec
/-- A morphism of presheaves `f : F ⟶ G` is locally surjective with respect to a grothendieck
topology if every section of `G` is locally in the image of `f`. -/
class IsLocallySurjective {F G : Cᵒᵖ ⥤ A} (f : F ⟶ G) : Prop where
imageSieve_mem {U : C} (s : G.obj (op U)) : imageSieve f s ∈ J U
#align category_theory.is_locally_surjective CategoryTheory.Presheaf.IsLocallySurjective
lemma imageSieve_mem {F G : Cᵒᵖ ⥤ A} (f : F ⟶ G) [IsLocallySurjective J f] {U : Cᵒᵖ}
(s : G.obj U) : imageSieve f s ∈ J U.unop :=
IsLocallySurjective.imageSieve_mem _
instance {F G : Cᵒᵖ ⥤ A} (f : F ⟶ G) [IsLocallySurjective J f] :
IsLocallySurjective J (whiskerRight f (forget A)) where
imageSieve_mem s := imageSieve_mem J f s
| Mathlib/CategoryTheory/Sites/LocallySurjective.lean | 101 | 105 | theorem isLocallySurjective_iff_imagePresheaf_sheafify_eq_top {F G : Cᵒᵖ ⥤ A} (f : F ⟶ G) :
IsLocallySurjective J f ↔ (imagePresheaf (whiskerRight f (forget A))).sheafify J = ⊤ := by |
simp only [Subpresheaf.ext_iff, Function.funext_iff, Set.ext_iff, top_subpresheaf_obj,
Set.top_eq_univ, Set.mem_univ, iff_true_iff]
exact ⟨fun H _ => H.imageSieve_mem, fun H => ⟨H _⟩⟩
|
/-
Copyright (c) 2020 Thomas Browning. All rights reserved.
Released under Apache 2.0 license as described in the file LICENSE.
Authors: Thomas Browning
-/
import Mathlib.Algebra.BigOperators.NatAntidiagonal
import Mathlib.Algebra.Polynomial.RingDivision
#align_import data.polynomial.mirror from "leanprover-community/mathlib"@"2196ab363eb097c008d4497125e0dde23fb36db2"
/-!
# "Mirror" of a univariate polynomial
In this file we define `Polynomial.mirror`, a variant of `Polynomial.reverse`. The difference
between `reverse` and `mirror` is that `reverse` will decrease the degree if the polynomial is
divisible by `X`.
## Main definitions
- `Polynomial.mirror`
## Main results
- `Polynomial.mirror_mul_of_domain`: `mirror` preserves multiplication.
- `Polynomial.irreducible_of_mirror`: an irreducibility criterion involving `mirror`
-/
namespace Polynomial
open Polynomial
section Semiring
variable {R : Type*} [Semiring R] (p q : R[X])
/-- mirror of a polynomial: reverses the coefficients while preserving `Polynomial.natDegree` -/
noncomputable def mirror :=
p.reverse * X ^ p.natTrailingDegree
#align polynomial.mirror Polynomial.mirror
@[simp]
theorem mirror_zero : (0 : R[X]).mirror = 0 := by simp [mirror]
#align polynomial.mirror_zero Polynomial.mirror_zero
theorem mirror_monomial (n : ℕ) (a : R) : (monomial n a).mirror = monomial n a := by
classical
by_cases ha : a = 0
· rw [ha, monomial_zero_right, mirror_zero]
· rw [mirror, reverse, natDegree_monomial n a, if_neg ha, natTrailingDegree_monomial ha, ←
C_mul_X_pow_eq_monomial, reflect_C_mul_X_pow, revAt_le (le_refl n), tsub_self, pow_zero,
mul_one]
#align polynomial.mirror_monomial Polynomial.mirror_monomial
theorem mirror_C (a : R) : (C a).mirror = C a :=
mirror_monomial 0 a
set_option linter.uppercaseLean3 false in
#align polynomial.mirror_C Polynomial.mirror_C
theorem mirror_X : X.mirror = (X : R[X]) :=
mirror_monomial 1 (1 : R)
set_option linter.uppercaseLean3 false in
#align polynomial.mirror_X Polynomial.mirror_X
theorem mirror_natDegree : p.mirror.natDegree = p.natDegree := by
by_cases hp : p = 0
· rw [hp, mirror_zero]
nontriviality R
rw [mirror, natDegree_mul', reverse_natDegree, natDegree_X_pow,
tsub_add_cancel_of_le p.natTrailingDegree_le_natDegree]
rwa [leadingCoeff_X_pow, mul_one, reverse_leadingCoeff, Ne, trailingCoeff_eq_zero]
#align polynomial.mirror_nat_degree Polynomial.mirror_natDegree
theorem mirror_natTrailingDegree : p.mirror.natTrailingDegree = p.natTrailingDegree := by
by_cases hp : p = 0
· rw [hp, mirror_zero]
· rw [mirror, natTrailingDegree_mul_X_pow ((mt reverse_eq_zero.mp) hp),
natTrailingDegree_reverse, zero_add]
#align polynomial.mirror_nat_trailing_degree Polynomial.mirror_natTrailingDegree
| Mathlib/Algebra/Polynomial/Mirror.lean | 82 | 97 | theorem coeff_mirror (n : ℕ) :
p.mirror.coeff n = p.coeff (revAt (p.natDegree + p.natTrailingDegree) n) := by |
by_cases h2 : p.natDegree < n
· rw [coeff_eq_zero_of_natDegree_lt (by rwa [mirror_natDegree])]
by_cases h1 : n ≤ p.natDegree + p.natTrailingDegree
· rw [revAt_le h1, coeff_eq_zero_of_lt_natTrailingDegree]
exact (tsub_lt_iff_left h1).mpr (Nat.add_lt_add_right h2 _)
· rw [← revAtFun_eq, revAtFun, if_neg h1, coeff_eq_zero_of_natDegree_lt h2]
rw [not_lt] at h2
rw [revAt_le (h2.trans (Nat.le_add_right _ _))]
by_cases h3 : p.natTrailingDegree ≤ n
· rw [← tsub_add_eq_add_tsub h2, ← tsub_tsub_assoc h2 h3, mirror, coeff_mul_X_pow', if_pos h3,
coeff_reverse, revAt_le (tsub_le_self.trans h2)]
rw [not_le] at h3
rw [coeff_eq_zero_of_natDegree_lt (lt_tsub_iff_right.mpr (Nat.add_lt_add_left h3 _))]
exact coeff_eq_zero_of_lt_natTrailingDegree (by rwa [mirror_natTrailingDegree])
|
/-
Copyright (c) 2023 Jireh Loreaux. All rights reserved.
Released under Apache 2.0 license as described in the file LICENSE.
Authors: Jireh Loreaux
-/
import Mathlib.Algebra.Algebra.Unitization
import Mathlib.Algebra.Star.NonUnitalSubalgebra
import Mathlib.Algebra.Star.Subalgebra
import Mathlib.GroupTheory.GroupAction.Ring
/-!
# Relating unital and non-unital substructures
This file relates various algebraic structures and provides maps (generally algebra homomorphisms),
from the unitization of a non-unital subobject into the full structure. The range of this map is
the unital closure of the non-unital subobject (e.g., `Algebra.adjoin`, `Subring.closure`,
`Subsemiring.closure` or `StarAlgebra.adjoin`). When the underlying scalar ring is a field, for
this map to be injective it suffices that the range omits `1`. In this setting we provide suitable
`AlgEquiv` (or `StarAlgEquiv`) onto the range.
## Main declarations
* `NonUnitalSubalgebra.unitization s : Unitization R s →ₐ[R] A`:
where `s` is a non-unital subalgebra of a unital `R`-algebra `A`, this is the natural algebra
homomorphism sending `(r, a)` to `r • 1 + a`. The range of this map is
`Algebra.adjoin R (s : Set A)`.
* `NonUnitalSubalgebra.unitizationAlgEquiv s : Unitization R s ≃ₐ[R] Algebra.adjoin R (s : Set A)`
when `R` is a field and `1 ∉ s`. This is `NonUnitalSubalgebra.unitization` upgraded to an
`AlgEquiv` onto its range.
* `NonUnitalSubsemiring.unitization : Unitization ℕ s →ₐ[ℕ] R`: the natural `ℕ`-algebra homomorphism
from the unitization of a non-unital subsemiring `s` into the ring containing it. The range of
this map is `subalgebraOfSubsemiring (Subsemiring.closure s)`.
This is just `NonUnitalSubalgebra.unitization s` but we provide a separate declaration because
there is an instance Lean can't find on its own due to `outParam`.
* `NonUnitalSubring.unitization : Unitization ℤ s →ₐ[ℤ] R`:
the natural `ℤ`-algebra homomorphism from the unitization of a non-unital subring `s` into the
ring containing it. The range of this map is `subalgebraOfSubring (Subring.closure s)`.
This is just `NonUnitalSubalgebra.unitization s` but we provide a separate declaration because
there is an instance Lean can't find on its own due to `outParam`.
* `NonUnitalStarSubalgebra s : Unitization R s →⋆ₐ[R] A`: a version of
`NonUnitalSubalgebra.unitization` for star algebras.
* `NonUnitalStarSubalgebra.unitizationStarAlgEquiv s :`
`Unitization R s ≃⋆ₐ[R] StarAlgebra.adjoin R (s : Set A)`:
a version of `NonUnitalSubalgebra.unitizationAlgEquiv` for star algebras.
-/
/-! ## Subalgebras -/
section Subalgebra
variable {R A : Type*} [CommSemiring R] [Semiring A] [Algebra R A]
/-- Turn a `Subalgebra` into a `NonUnitalSubalgebra` by forgetting that it contains `1`. -/
def Subalgebra.toNonUnitalSubalgebra (S : Subalgebra R A) : NonUnitalSubalgebra R A :=
{ S with
smul_mem' := fun r _x hx => S.smul_mem hx r }
theorem Subalgebra.one_mem_toNonUnitalSubalgebra (S : Subalgebra R A) :
(1 : A) ∈ S.toNonUnitalSubalgebra :=
S.one_mem
/-- Turn a non-unital subalgebra containing `1` into a subalgebra. -/
def NonUnitalSubalgebra.toSubalgebra (S : NonUnitalSubalgebra R A) (h1 : (1 : A) ∈ S) :
Subalgebra R A :=
{ S with
one_mem' := h1
algebraMap_mem' := fun r =>
(Algebra.algebraMap_eq_smul_one (R := R) (A := A) r).symm ▸ SMulMemClass.smul_mem r h1 }
theorem Subalgebra.toNonUnitalSubalgebra_toSubalgebra (S : Subalgebra R A) :
S.toNonUnitalSubalgebra.toSubalgebra S.one_mem = S := by cases S; rfl
| Mathlib/Algebra/Algebra/Subalgebra/Unitization.lean | 73 | 75 | theorem NonUnitalSubalgebra.toSubalgebra_toNonUnitalSubalgebra (S : NonUnitalSubalgebra R A)
(h1 : (1 : A) ∈ S) : (NonUnitalSubalgebra.toSubalgebra S h1).toNonUnitalSubalgebra = S := by |
cases S; rfl
|
/-
Copyright (c) 2020 Yury G. Kudryashov. All rights reserved.
Released under Apache 2.0 license as described in the file LICENSE.
Authors: Yury G. Kudryashov
-/
import Mathlib.Algebra.BigOperators.NatAntidiagonal
import Mathlib.Algebra.Order.Ring.Abs
import Mathlib.Data.Nat.Choose.Sum
import Mathlib.RingTheory.PowerSeries.Basic
#align_import ring_theory.power_series.well_known from "leanprover-community/mathlib"@"8199f6717c150a7fe91c4534175f4cf99725978f"
/-!
# Definition of well-known power series
In this file we define the following power series:
* `PowerSeries.invUnitsSub`: given `u : Rˣ`, this is the series for `1 / (u - x)`.
It is given by `∑ n, x ^ n /ₚ u ^ (n + 1)`.
* `PowerSeries.invOneSubPow`: given a commutative ring `S` and a number `d : ℕ`,
`PowerSeries.invOneSubPow d : S⟦X⟧ˣ` is the power series `∑ n, Nat.choose (d + n) d`
whose multiplicative inverse is `(1 - X) ^ (d + 1)`.
* `PowerSeries.sin`, `PowerSeries.cos`, `PowerSeries.exp` : power series for sin, cosine, and
exponential functions.
-/
namespace PowerSeries
section Ring
variable {R S : Type*} [Ring R] [Ring S]
/-- The power series for `1 / (u - x)`. -/
def invUnitsSub (u : Rˣ) : PowerSeries R :=
mk fun n => 1 /ₚ u ^ (n + 1)
#align power_series.inv_units_sub PowerSeries.invUnitsSub
@[simp]
theorem coeff_invUnitsSub (u : Rˣ) (n : ℕ) : coeff R n (invUnitsSub u) = 1 /ₚ u ^ (n + 1) :=
coeff_mk _ _
#align power_series.coeff_inv_units_sub PowerSeries.coeff_invUnitsSub
@[simp]
theorem constantCoeff_invUnitsSub (u : Rˣ) : constantCoeff R (invUnitsSub u) = 1 /ₚ u := by
rw [← coeff_zero_eq_constantCoeff_apply, coeff_invUnitsSub, zero_add, pow_one]
#align power_series.constant_coeff_inv_units_sub PowerSeries.constantCoeff_invUnitsSub
@[simp]
theorem invUnitsSub_mul_X (u : Rˣ) : invUnitsSub u * X = invUnitsSub u * C R u - 1 := by
ext (_ | n)
· simp
· simp [n.succ_ne_zero, pow_succ']
set_option linter.uppercaseLean3 false in
#align power_series.inv_units_sub_mul_X PowerSeries.invUnitsSub_mul_X
@[simp]
theorem invUnitsSub_mul_sub (u : Rˣ) : invUnitsSub u * (C R u - X) = 1 := by
simp [mul_sub, sub_sub_cancel]
#align power_series.inv_units_sub_mul_sub PowerSeries.invUnitsSub_mul_sub
theorem map_invUnitsSub (f : R →+* S) (u : Rˣ) :
map f (invUnitsSub u) = invUnitsSub (Units.map (f : R →* S) u) := by
ext
simp only [← map_pow, coeff_map, coeff_invUnitsSub, one_divp]
rfl
#align power_series.map_inv_units_sub PowerSeries.map_invUnitsSub
end Ring
section invOneSubPow
variable {S : Type*} [CommRing S] (d : ℕ)
/--
(1 + X + X^2 + ...) * (1 - X) = 1.
Note that the power series `1 + X + X^2 + ...` is written as `mk 1` where `1` is the constant
function so that `mk 1` is the power series with all coefficients equal to one.
-/
theorem mk_one_mul_one_sub_eq_one : (mk 1 : S⟦X⟧) * (1 - X) = 1 := by
rw [mul_comm, ext_iff]
intro n
cases n with
| zero => simp
| succ n => simp [sub_mul]
/--
Note that `mk 1` is the constant function `1` so the power series `1 + X + X^2 + ...`. This theorem
states that for any `d : ℕ`, `(1 + X + X^2 + ... : S⟦X⟧) ^ (d + 1)` is equal to the power series
`mk fun n => Nat.choose (d + n) d : S⟦X⟧`.
-/
theorem mk_one_pow_eq_mk_choose_add :
(mk 1 : S⟦X⟧) ^ (d + 1) = (mk fun n => Nat.choose (d + n) d : S⟦X⟧) := by
induction d with
| zero => ext; simp
| succ d hd =>
ext n
rw [pow_add, hd, pow_one, mul_comm, coeff_mul]
simp_rw [coeff_mk, Pi.one_apply, one_mul]
norm_cast
rw [Finset.sum_antidiagonal_choose_add, ← Nat.choose_succ_succ, Nat.succ_eq_add_one,
add_right_comm]
/--
The power series `mk fun n => Nat.choose (d + n) d`, whose multiplicative inverse is
`(1 - X) ^ (d + 1)`.
-/
noncomputable def invOneSubPow : S⟦X⟧ˣ where
val := mk fun n => Nat.choose (d + n) d
inv := (1 - X) ^ (d + 1)
val_inv := by
rw [← mk_one_pow_eq_mk_choose_add, ← mul_pow, mk_one_mul_one_sub_eq_one, one_pow]
inv_val := by
rw [← mk_one_pow_eq_mk_choose_add, ← mul_pow, mul_comm, mk_one_mul_one_sub_eq_one, one_pow]
theorem invOneSubPow_val_eq_mk_choose_add :
(invOneSubPow d).val = (mk fun n => Nat.choose (d + n) d : S⟦X⟧) := rfl
| Mathlib/RingTheory/PowerSeries/WellKnown.lean | 123 | 125 | theorem invOneSubPow_val_zero_eq_invUnitSub_one :
(invOneSubPow 0).val = invUnitsSub (1 : Sˣ) := by |
simp [invOneSubPow, invUnitsSub]
|
/-
Copyright (c) 2020 Aaron Anderson. All rights reserved.
Released under Apache 2.0 license as described in the file LICENSE.
Authors: Aaron Anderson
-/
import Mathlib.Data.Finset.Fold
import Mathlib.Algebra.GCDMonoid.Multiset
#align_import algebra.gcd_monoid.finset from "leanprover-community/mathlib"@"9003f28797c0664a49e4179487267c494477d853"
#align_import algebra.gcd_monoid.div from "leanprover-community/mathlib"@"b537794f8409bc9598febb79cd510b1df5f4539d"
/-!
# GCD and LCM operations on finsets
## Main definitions
- `Finset.gcd` - the greatest common denominator of a `Finset` of elements of a `GCDMonoid`
- `Finset.lcm` - the least common multiple of a `Finset` of elements of a `GCDMonoid`
## Implementation notes
Many of the proofs use the lemmas `gcd_def` and `lcm_def`, which relate `Finset.gcd`
and `Finset.lcm` to `Multiset.gcd` and `Multiset.lcm`.
TODO: simplify with a tactic and `Data.Finset.Lattice`
## Tags
finset, gcd
-/
variable {ι α β γ : Type*}
namespace Finset
open Multiset
variable [CancelCommMonoidWithZero α] [NormalizedGCDMonoid α]
/-! ### lcm -/
section lcm
/-- Least common multiple of a finite set -/
def lcm (s : Finset β) (f : β → α) : α :=
s.fold GCDMonoid.lcm 1 f
#align finset.lcm Finset.lcm
variable {s s₁ s₂ : Finset β} {f : β → α}
theorem lcm_def : s.lcm f = (s.1.map f).lcm :=
rfl
#align finset.lcm_def Finset.lcm_def
@[simp]
theorem lcm_empty : (∅ : Finset β).lcm f = 1 :=
fold_empty
#align finset.lcm_empty Finset.lcm_empty
@[simp]
theorem lcm_dvd_iff {a : α} : s.lcm f ∣ a ↔ ∀ b ∈ s, f b ∣ a := by
apply Iff.trans Multiset.lcm_dvd
simp only [Multiset.mem_map, and_imp, exists_imp]
exact ⟨fun k b hb ↦ k _ _ hb rfl, fun k a' b hb h ↦ h ▸ k _ hb⟩
#align finset.lcm_dvd_iff Finset.lcm_dvd_iff
theorem lcm_dvd {a : α} : (∀ b ∈ s, f b ∣ a) → s.lcm f ∣ a :=
lcm_dvd_iff.2
#align finset.lcm_dvd Finset.lcm_dvd
theorem dvd_lcm {b : β} (hb : b ∈ s) : f b ∣ s.lcm f :=
lcm_dvd_iff.1 dvd_rfl _ hb
#align finset.dvd_lcm Finset.dvd_lcm
@[simp]
| Mathlib/Algebra/GCDMonoid/Finset.lean | 77 | 82 | theorem lcm_insert [DecidableEq β] {b : β} :
(insert b s : Finset β).lcm f = GCDMonoid.lcm (f b) (s.lcm f) := by |
by_cases h : b ∈ s
· rw [insert_eq_of_mem h,
(lcm_eq_right_iff (f b) (s.lcm f) (Multiset.normalize_lcm (s.1.map f))).2 (dvd_lcm h)]
apply fold_insert h
|
/-
Copyright (c) 2022 Thomas Browning. All rights reserved.
Released under Apache 2.0 license as described in the file LICENSE.
Authors: Thomas Browning
-/
import Mathlib.Algebra.Group.ConjFinite
import Mathlib.GroupTheory.Abelianization
import Mathlib.GroupTheory.GroupAction.ConjAct
import Mathlib.GroupTheory.GroupAction.Quotient
import Mathlib.GroupTheory.Index
import Mathlib.GroupTheory.SpecificGroups.Dihedral
import Mathlib.Tactic.FieldSimp
import Mathlib.Tactic.LinearCombination
import Mathlib.Tactic.Qify
#align_import group_theory.commuting_probability from "leanprover-community/mathlib"@"dc6c365e751e34d100e80fe6e314c3c3e0fd2988"
/-!
# Commuting Probability
This file introduces the commuting probability of finite groups.
## Main definitions
* `commProb`: The commuting probability of a finite type with a multiplication operation.
## Todo
* Neumann's theorem.
-/
noncomputable section
open scoped Classical
open Fintype
variable (M : Type*) [Mul M]
/-- The commuting probability of a finite type with a multiplication operation. -/
def commProb : ℚ :=
Nat.card { p : M × M // Commute p.1 p.2 } / (Nat.card M : ℚ) ^ 2
#align comm_prob commProb
theorem commProb_def :
commProb M = Nat.card { p : M × M // Commute p.1 p.2 } / (Nat.card M : ℚ) ^ 2 :=
rfl
#align comm_prob_def commProb_def
theorem commProb_prod (M' : Type*) [Mul M'] : commProb (M × M') = commProb M * commProb M' := by
simp_rw [commProb_def, div_mul_div_comm, Nat.card_prod, Nat.cast_mul, mul_pow, ← Nat.cast_mul,
← Nat.card_prod, Commute, SemiconjBy, Prod.ext_iff]
congr 2
exact Nat.card_congr ⟨fun x => ⟨⟨⟨x.1.1.1, x.1.2.1⟩, x.2.1⟩, ⟨⟨x.1.1.2, x.1.2.2⟩, x.2.2⟩⟩,
fun x => ⟨⟨⟨x.1.1.1, x.2.1.1⟩, ⟨x.1.1.2, x.2.1.2⟩⟩, ⟨x.1.2, x.2.2⟩⟩, fun x => rfl, fun x => rfl⟩
theorem commProb_pi {α : Type*} (i : α → Type*) [Fintype α] [∀ a, Mul (i a)] :
commProb (∀ a, i a) = ∏ a, commProb (i a) := by
simp_rw [commProb_def, Finset.prod_div_distrib, Finset.prod_pow, ← Nat.cast_prod,
← Nat.card_pi, Commute, SemiconjBy, Function.funext_iff]
congr 2
exact Nat.card_congr ⟨fun x a => ⟨⟨x.1.1 a, x.1.2 a⟩, x.2 a⟩, fun x => ⟨⟨fun a => (x a).1.1,
fun a => (x a).1.2⟩, fun a => (x a).2⟩, fun x => rfl, fun x => rfl⟩
theorem commProb_function {α β : Type*} [Fintype α] [Mul β] :
commProb (α → β) = (commProb β) ^ Fintype.card α := by
rw [commProb_pi, Finset.prod_const, Finset.card_univ]
@[simp]
theorem commProb_eq_zero_of_infinite [Infinite M] : commProb M = 0 :=
div_eq_zero_iff.2 (Or.inl (Nat.cast_eq_zero.2 Nat.card_eq_zero_of_infinite))
variable [Finite M]
theorem commProb_pos [h : Nonempty M] : 0 < commProb M :=
h.elim fun x ↦
div_pos (Nat.cast_pos.mpr (Finite.card_pos_iff.mpr ⟨⟨(x, x), rfl⟩⟩))
(pow_pos (Nat.cast_pos.mpr Finite.card_pos) 2)
#align comm_prob_pos commProb_pos
| Mathlib/GroupTheory/CommutingProbability.lean | 78 | 81 | theorem commProb_le_one : commProb M ≤ 1 := by |
refine div_le_one_of_le ?_ (sq_nonneg (Nat.card M : ℚ))
rw [← Nat.cast_pow, Nat.cast_le, sq, ← Nat.card_prod]
apply Finite.card_subtype_le
|
/-
Copyright (c) 2022 Johannes Hölzl. All rights reserved.
Released under Apache 2.0 license as described in the file LICENSE.
Authors: Johanes Hölzl, Patrick Massot, Yury Kudryashov, Kevin Wilson, Heather Macbeth
-/
import Mathlib.Order.Filter.Basic
#align_import order.filter.prod from "leanprover-community/mathlib"@"d6fad0e5bf2d6f48da9175d25c3dc5706b3834ce"
/-!
# Product and coproduct filters
In this file we define `Filter.prod f g` (notation: `f ×ˢ g`) and `Filter.coprod f g`. The product
of two filters is the largest filter `l` such that `Filter.Tendsto Prod.fst l f` and
`Filter.Tendsto Prod.snd l g`.
## Implementation details
The product filter cannot be defined using the monad structure on filters. For example:
```lean
F := do {x ← seq, y ← top, return (x, y)}
G := do {y ← top, x ← seq, return (x, y)}
```
hence:
```lean
s ∈ F ↔ ∃ n, [n..∞] × univ ⊆ s
s ∈ G ↔ ∀ i:ℕ, ∃ n, [n..∞] × {i} ⊆ s
```
Now `⋃ i, [i..∞] × {i}` is in `G` but not in `F`.
As product filter we want to have `F` as result.
## Notations
* `f ×ˢ g` : `Filter.prod f g`, localized in `Filter`.
-/
open Set
open Filter
namespace Filter
variable {α β γ δ : Type*} {ι : Sort*}
section Prod
variable {s : Set α} {t : Set β} {f : Filter α} {g : Filter β}
/-- Product of filters. This is the filter generated by cartesian products
of elements of the component filters. -/
protected def prod (f : Filter α) (g : Filter β) : Filter (α × β) :=
f.comap Prod.fst ⊓ g.comap Prod.snd
#align filter.prod Filter.prod
instance instSProd : SProd (Filter α) (Filter β) (Filter (α × β)) where
sprod := Filter.prod
theorem prod_mem_prod (hs : s ∈ f) (ht : t ∈ g) : s ×ˢ t ∈ f ×ˢ g :=
inter_mem_inf (preimage_mem_comap hs) (preimage_mem_comap ht)
#align filter.prod_mem_prod Filter.prod_mem_prod
theorem mem_prod_iff {s : Set (α × β)} {f : Filter α} {g : Filter β} :
s ∈ f ×ˢ g ↔ ∃ t₁ ∈ f, ∃ t₂ ∈ g, t₁ ×ˢ t₂ ⊆ s := by
simp only [SProd.sprod, Filter.prod]
constructor
· rintro ⟨t₁, ⟨s₁, hs₁, hts₁⟩, t₂, ⟨s₂, hs₂, hts₂⟩, rfl⟩
exact ⟨s₁, hs₁, s₂, hs₂, fun p ⟨h, h'⟩ => ⟨hts₁ h, hts₂ h'⟩⟩
· rintro ⟨t₁, ht₁, t₂, ht₂, h⟩
exact mem_inf_of_inter (preimage_mem_comap ht₁) (preimage_mem_comap ht₂) h
#align filter.mem_prod_iff Filter.mem_prod_iff
@[simp]
theorem prod_mem_prod_iff [f.NeBot] [g.NeBot] : s ×ˢ t ∈ f ×ˢ g ↔ s ∈ f ∧ t ∈ g :=
⟨fun h =>
let ⟨_s', hs', _t', ht', H⟩ := mem_prod_iff.1 h
(prod_subset_prod_iff.1 H).elim
(fun ⟨hs's, ht't⟩ => ⟨mem_of_superset hs' hs's, mem_of_superset ht' ht't⟩) fun h =>
h.elim (fun hs'e => absurd hs'e (nonempty_of_mem hs').ne_empty) fun ht'e =>
absurd ht'e (nonempty_of_mem ht').ne_empty,
fun h => prod_mem_prod h.1 h.2⟩
#align filter.prod_mem_prod_iff Filter.prod_mem_prod_iff
theorem mem_prod_principal {s : Set (α × β)} :
s ∈ f ×ˢ 𝓟 t ↔ { a | ∀ b ∈ t, (a, b) ∈ s } ∈ f := by
rw [← @exists_mem_subset_iff _ f, mem_prod_iff]
refine exists_congr fun u => Iff.rfl.and ⟨?_, fun h => ⟨t, mem_principal_self t, ?_⟩⟩
· rintro ⟨v, v_in, hv⟩ a a_in b b_in
exact hv (mk_mem_prod a_in <| v_in b_in)
· rintro ⟨x, y⟩ ⟨hx, hy⟩
exact h hx y hy
#align filter.mem_prod_principal Filter.mem_prod_principal
theorem mem_prod_top {s : Set (α × β)} :
s ∈ f ×ˢ (⊤ : Filter β) ↔ { a | ∀ b, (a, b) ∈ s } ∈ f := by
rw [← principal_univ, mem_prod_principal]
simp only [mem_univ, forall_true_left]
#align filter.mem_prod_top Filter.mem_prod_top
| Mathlib/Order/Filter/Prod.lean | 101 | 104 | theorem eventually_prod_principal_iff {p : α × β → Prop} {s : Set β} :
(∀ᶠ x : α × β in f ×ˢ 𝓟 s, p x) ↔ ∀ᶠ x : α in f, ∀ y : β, y ∈ s → p (x, y) := by |
rw [eventually_iff, eventually_iff, mem_prod_principal]
simp only [mem_setOf_eq]
|
/-
Copyright (c) 2022 Dagur Tómas Ásgeirsson. All rights reserved.
Released under Apache 2.0 license as described in the file LICENSE.
Authors: Dagur Tómas Ásgeirsson, Leonardo de Moura
-/
import Mathlib.Data.Set.Basic
#align_import data.set.bool_indicator from "leanprover-community/mathlib"@"fc2ed6f838ce7c9b7c7171e58d78eaf7b438fb0e"
/-!
# Indicator function valued in bool
See also `Set.indicator` and `Set.piecewise`.
-/
open Bool
namespace Set
variable {α : Type*} (s : Set α)
/-- `boolIndicator` maps `x` to `true` if `x ∈ s`, else to `false` -/
noncomputable def boolIndicator (x : α) :=
@ite _ (x ∈ s) (Classical.propDecidable _) true false
#align set.bool_indicator Set.boolIndicator
theorem mem_iff_boolIndicator (x : α) : x ∈ s ↔ s.boolIndicator x = true := by
unfold boolIndicator
split_ifs with h <;> simp [h]
#align set.mem_iff_bool_indicator Set.mem_iff_boolIndicator
| Mathlib/Data/Set/BoolIndicator.lean | 32 | 34 | theorem not_mem_iff_boolIndicator (x : α) : x ∉ s ↔ s.boolIndicator x = false := by |
unfold boolIndicator
split_ifs with h <;> simp [h]
|
/-
Copyright (c) 2014 Robert Lewis. All rights reserved.
Released under Apache 2.0 license as described in the file LICENSE.
Authors: Robert Lewis, Leonardo de Moura, Johannes Hölzl, Mario Carneiro
-/
import Mathlib.Algebra.Field.Defs
import Mathlib.Tactic.Common
#align_import algebra.field.defs from "leanprover-community/mathlib"@"2651125b48fc5c170ab1111afd0817c903b1fc6c"
/-!
# `IsField` predicate
Predicate on a (semi)ring that it is a (semi)field, i.e. that the multiplication is
commutative, that it has more than one element and that all non-zero elements have a
multiplicative inverse. In contrast to `Field`, which contains the data of a function associating
to an element of the field its multiplicative inverse, this predicate only assumes the existence
and can therefore more easily be used to e.g. transfer along ring isomorphisms.
-/
universe u
section IsField
/-- A predicate to express that a (semi)ring is a (semi)field.
This is mainly useful because such a predicate does not contain data,
and can therefore be easily transported along ring isomorphisms.
Additionally, this is useful when trying to prove that
a particular ring structure extends to a (semi)field. -/
structure IsField (R : Type u) [Semiring R] : Prop where
/-- For a semiring to be a field, it must have two distinct elements. -/
exists_pair_ne : ∃ x y : R, x ≠ y
/-- Fields are commutative. -/
mul_comm : ∀ x y : R, x * y = y * x
/-- Nonzero elements have multiplicative inverses. -/
mul_inv_cancel : ∀ {a : R}, a ≠ 0 → ∃ b, a * b = 1
#align is_field IsField
/-- Transferring from `Semifield` to `IsField`. -/
theorem Semifield.toIsField (R : Type u) [Semifield R] : IsField R where
__ := ‹Semifield R›
mul_inv_cancel {a} ha := ⟨a⁻¹, mul_inv_cancel ha⟩
#align semifield.to_is_field Semifield.toIsField
/-- Transferring from `Field` to `IsField`. -/
theorem Field.toIsField (R : Type u) [Field R] : IsField R :=
Semifield.toIsField _
#align field.to_is_field Field.toIsField
@[simp]
theorem IsField.nontrivial {R : Type u} [Semiring R] (h : IsField R) : Nontrivial R :=
⟨h.exists_pair_ne⟩
#align is_field.nontrivial IsField.nontrivial
@[simp]
theorem not_isField_of_subsingleton (R : Type u) [Semiring R] [Subsingleton R] : ¬IsField R :=
fun h =>
let ⟨_, _, h⟩ := h.exists_pair_ne
h (Subsingleton.elim _ _)
#align not_is_field_of_subsingleton not_isField_of_subsingleton
open scoped Classical
/-- Transferring from `IsField` to `Semifield`. -/
noncomputable def IsField.toSemifield {R : Type u} [Semiring R] (h : IsField R) : Semifield R where
__ := ‹Semiring R›
__ := h
inv a := if ha : a = 0 then 0 else Classical.choose (h.mul_inv_cancel ha)
inv_zero := dif_pos rfl
mul_inv_cancel a ha := by convert Classical.choose_spec (h.mul_inv_cancel ha); exact dif_neg ha
nnqsmul := _
#align is_field.to_semifield IsField.toSemifield
/-- Transferring from `IsField` to `Field`. -/
noncomputable def IsField.toField {R : Type u} [Ring R] (h : IsField R) : Field R :=
{ ‹Ring R›, IsField.toSemifield h with qsmul := _ }
#align is_field.to_field IsField.toField
/-- For each field, and for each nonzero element of said field, there is a unique inverse.
Since `IsField` doesn't remember the data of an `inv` function and as such,
a lemma that there is a unique inverse could be useful.
-/
| Mathlib/Algebra/Field/IsField.lean | 84 | 93 | theorem uniq_inv_of_isField (R : Type u) [Ring R] (hf : IsField R) :
∀ x : R, x ≠ 0 → ∃! y : R, x * y = 1 := by |
intro x hx
apply exists_unique_of_exists_of_unique
· exact hf.mul_inv_cancel hx
· intro y z hxy hxz
calc
y = y * (x * z) := by rw [hxz, mul_one]
_ = x * y * z := by rw [← mul_assoc, hf.mul_comm y x]
_ = z := by rw [hxy, one_mul]
|
/-
Copyright (c) 2017 Johannes Hölzl. All rights reserved.
Released under Apache 2.0 license as described in the file LICENSE.
Authors: Johannes Hölzl, Mario Carneiro
-/
import Mathlib.MeasureTheory.OuterMeasure.Caratheodory
/-!
# Induced Outer Measure
We can extend a function defined on a subset of `Set α` to an outer measure.
The underlying function is called `extend`, and the measure it induces is called
`inducedOuterMeasure`.
Some lemmas below are proven twice, once in the general case, and one where the function `m`
is only defined on measurable sets (i.e. when `P = MeasurableSet`). In the latter cases, we can
remove some hypotheses in the statement. The general version has the same name, but with a prime
at the end.
## Tags
outer measure
-/
#align_import measure_theory.measure.outer_measure from "leanprover-community/mathlib"@"343e80208d29d2d15f8050b929aa50fe4ce71b55"
noncomputable section
open Set Function Filter
open scoped Classical NNReal Topology ENNReal
namespace MeasureTheory
open OuterMeasure
section Extend
variable {α : Type*} {P : α → Prop}
variable (m : ∀ s : α, P s → ℝ≥0∞)
/-- We can trivially extend a function defined on a subclass of objects (with codomain `ℝ≥0∞`)
to all objects by defining it to be `∞` on the objects not in the class. -/
def extend (s : α) : ℝ≥0∞ :=
⨅ h : P s, m s h
#align measure_theory.extend MeasureTheory.extend
theorem extend_eq {s : α} (h : P s) : extend m s = m s h := by simp [extend, h]
#align measure_theory.extend_eq MeasureTheory.extend_eq
theorem extend_eq_top {s : α} (h : ¬P s) : extend m s = ∞ := by simp [extend, h]
#align measure_theory.extend_eq_top MeasureTheory.extend_eq_top
theorem smul_extend {R} [Zero R] [SMulWithZero R ℝ≥0∞] [IsScalarTower R ℝ≥0∞ ℝ≥0∞]
[NoZeroSMulDivisors R ℝ≥0∞] {c : R} (hc : c ≠ 0) :
c • extend m = extend fun s h => c • m s h := by
ext1 s
dsimp [extend]
by_cases h : P s
· simp [h]
· simp [h, ENNReal.smul_top, hc]
#align measure_theory.smul_extend MeasureTheory.smul_extend
| Mathlib/MeasureTheory/OuterMeasure/Induced.lean | 65 | 68 | theorem le_extend {s : α} (h : P s) : m s h ≤ extend m s := by |
simp only [extend, le_iInf_iff]
intro
rfl
|
/-
Copyright (c) 2023 Eric Wieser. All rights reserved.
Released under Apache 2.0 license as described in the file LICENSE.
Authors: Eric Wieser
-/
import Mathlib.LinearAlgebra.BilinearForm.TensorProduct
import Mathlib.LinearAlgebra.QuadraticForm.Basic
/-!
# The quadratic form on a tensor product
## Main definitions
* `QuadraticForm.tensorDistrib (Q₁ ⊗ₜ Q₂)`: the quadratic form on `M₁ ⊗ M₂` constructed by applying
`Q₁` on `M₁` and `Q₂` on `M₂`. This construction is not available in characteristic two.
-/
universe uR uA uM₁ uM₂
variable {R : Type uR} {A : Type uA} {M₁ : Type uM₁} {M₂ : Type uM₂}
open TensorProduct
open LinearMap (BilinForm)
namespace QuadraticForm
section CommRing
variable [CommRing R] [CommRing A]
variable [AddCommGroup M₁] [AddCommGroup M₂]
variable [Algebra R A] [Module R M₁] [Module A M₁]
variable [SMulCommClass R A M₁] [SMulCommClass A R M₁] [IsScalarTower R A M₁]
variable [Module R M₂] [Invertible (2 : R)]
variable (R A) in
/-- The tensor product of two quadratic forms injects into quadratic forms on tensor products.
Note this is heterobasic; the quadratic form on the left can take values in a larger ring than
the one on the right. -/
-- `noncomputable` is a performance workaround for mathlib4#7103
noncomputable def tensorDistrib :
QuadraticForm A M₁ ⊗[R] QuadraticForm R M₂ →ₗ[A] QuadraticForm A (M₁ ⊗[R] M₂) :=
letI : Invertible (2 : A) := (Invertible.map (algebraMap R A) 2).copy 2 (map_ofNat _ _).symm
-- while `letI`s would produce a better term than `let`, they would make this already-slow
-- definition even slower.
let toQ := BilinForm.toQuadraticFormLinearMap A A (M₁ ⊗[R] M₂)
let tmulB := BilinForm.tensorDistrib R A (M₁ := M₁) (M₂ := M₂)
let toB := AlgebraTensorModule.map
(QuadraticForm.associated : QuadraticForm A M₁ →ₗ[A] BilinForm A M₁)
(QuadraticForm.associated : QuadraticForm R M₂ →ₗ[R] BilinForm R M₂)
toQ ∘ₗ tmulB ∘ₗ toB
-- TODO: make the RHS `MulOpposite.op (Q₂ m₂) • Q₁ m₁` so that this has a nicer defeq for
-- `R = A` of `Q₁ m₁ * Q₂ m₂`.
@[simp]
theorem tensorDistrib_tmul (Q₁ : QuadraticForm A M₁) (Q₂ : QuadraticForm R M₂) (m₁ : M₁) (m₂ : M₂) :
tensorDistrib R A (Q₁ ⊗ₜ Q₂) (m₁ ⊗ₜ m₂) = Q₂ m₂ • Q₁ m₁ :=
letI : Invertible (2 : A) := (Invertible.map (algebraMap R A) 2).copy 2 (map_ofNat _ _).symm
(BilinForm.tensorDistrib_tmul _ _ _ _ _ _).trans <| congr_arg₂ _
(associated_eq_self_apply _ _ _) (associated_eq_self_apply _ _ _)
/-- The tensor product of two quadratic forms, a shorthand for dot notation. -/
-- `noncomputable` is a performance workaround for mathlib4#7103
protected noncomputable abbrev tmul (Q₁ : QuadraticForm A M₁) (Q₂ : QuadraticForm R M₂) :
QuadraticForm A (M₁ ⊗[R] M₂) :=
tensorDistrib R A (Q₁ ⊗ₜ[R] Q₂)
theorem associated_tmul [Invertible (2 : A)] (Q₁ : QuadraticForm A M₁) (Q₂ : QuadraticForm R M₂) :
associated (R := A) (Q₁.tmul Q₂)
= (associated (R := A) Q₁).tmul (associated (R := R) Q₂) := by
rw [QuadraticForm.tmul, tensorDistrib, BilinForm.tmul]
dsimp
have : Subsingleton (Invertible (2 : A)) := inferInstance
convert associated_left_inverse A ((associated_isSymm A Q₁).tmul (associated_isSymm R Q₂))
theorem polarBilin_tmul [Invertible (2 : A)] (Q₁ : QuadraticForm A M₁) (Q₂ : QuadraticForm R M₂) :
polarBilin (Q₁.tmul Q₂) = ⅟(2 : A) • (polarBilin Q₁).tmul (polarBilin Q₂) := by
simp_rw [← two_nsmul_associated A, ← two_nsmul_associated R, BilinForm.tmul, tmul_smul,
← smul_tmul', map_nsmul, associated_tmul]
rw [smul_comm (_ : A) (_ : ℕ), ← smul_assoc, two_smul _ (_ : A), invOf_two_add_invOf_two,
one_smul]
variable (A) in
/-- The base change of a quadratic form. -/
-- `noncomputable` is a performance workaround for mathlib4#7103
protected noncomputable def baseChange (Q : QuadraticForm R M₂) : QuadraticForm A (A ⊗[R] M₂) :=
QuadraticForm.tmul (R := R) (A := A) (M₁ := A) (M₂ := M₂) (QuadraticForm.sq (R := A)) Q
@[simp]
theorem baseChange_tmul (Q : QuadraticForm R M₂) (a : A) (m₂ : M₂) :
Q.baseChange A (a ⊗ₜ m₂) = Q m₂ • (a * a) :=
tensorDistrib_tmul _ _ _ _
| Mathlib/LinearAlgebra/QuadraticForm/TensorProduct.lean | 95 | 99 | theorem associated_baseChange [Invertible (2 : A)] (Q : QuadraticForm R M₂) :
associated (R := A) (Q.baseChange A) = (associated (R := R) Q).baseChange A := by |
dsimp only [QuadraticForm.baseChange, LinearMap.baseChange]
rw [associated_tmul (QuadraticForm.sq (R := A)) Q, associated_sq]
exact rfl
|
/-
Copyright (c) 2023 Yury Kudryashov. All rights reserved.
Released under Apache 2.0 license as described in the file LICENSE.
Authors: Yury Kudryashov
-/
import Mathlib.MeasureTheory.Function.AEEqFun.DomAct
import Mathlib.MeasureTheory.Function.LpSpace
/-!
# Action of `Mᵈᵐᵃ` on `Lᵖ` spaces
In this file we define action of `Mᵈᵐᵃ` on `MeasureTheory.Lp E p μ`
If `f : α → E` is a function representing an equivalence class in `Lᵖ(α, E)`, `M` acts on `α`,
and `c : M`, then `(.mk c : Mᵈᵐᵃ) • [f]` is represented by the function `a ↦ f (c • a)`.
We also prove basic properties of this action.
-/
set_option autoImplicit true
open MeasureTheory Filter
open scoped ENNReal
namespace DomMulAct
variable {M N α E : Type*} [MeasurableSpace M] [MeasurableSpace N]
[MeasurableSpace α] [NormedAddCommGroup E] {μ : MeasureTheory.Measure α} {p : ℝ≥0∞}
section SMul
variable [SMul M α] [SMulInvariantMeasure M α μ] [MeasurableSMul M α]
@[to_additive]
instance : SMul Mᵈᵐᵃ (Lp E p μ) where
smul c f := Lp.compMeasurePreserving (mk.symm c • ·) (measurePreserving_smul _ _) f
@[to_additive (attr := simp)]
theorem smul_Lp_val (c : Mᵈᵐᵃ) (f : Lp E p μ) : (c • f).1 = c • f.1 := rfl
@[to_additive]
theorem smul_Lp_ae_eq (c : Mᵈᵐᵃ) (f : Lp E p μ) : c • f =ᵐ[μ] (f <| mk.symm c • ·) :=
Lp.coeFn_compMeasurePreserving _ _
@[to_additive]
theorem mk_smul_toLp (c : M) {f : α → E} (hf : Memℒp f p μ) :
mk c • hf.toLp f =
(hf.comp_measurePreserving <| measurePreserving_smul c μ).toLp (f <| c • ·) :=
rfl
@[to_additive (attr := simp)]
theorem smul_Lp_const [IsFiniteMeasure μ] (c : Mᵈᵐᵃ) (a : E) :
c • Lp.const p μ a = Lp.const p μ a :=
rfl
instance [SMul N α] [SMulCommClass M N α] [SMulInvariantMeasure N α μ] [MeasurableSMul N α] :
SMulCommClass Mᵈᵐᵃ Nᵈᵐᵃ (Lp E p μ) :=
Subtype.val_injective.smulCommClass (fun _ _ ↦ rfl) fun _ _ ↦ rfl
instance [NormedRing 𝕜] [Module 𝕜 E] [BoundedSMul 𝕜 E] : SMulCommClass Mᵈᵐᵃ 𝕜 (Lp E p μ) :=
Subtype.val_injective.smulCommClass (fun _ _ ↦ rfl) fun _ _ ↦ rfl
instance [NormedRing 𝕜] [Module 𝕜 E] [BoundedSMul 𝕜 E] : SMulCommClass 𝕜 Mᵈᵐᵃ (Lp E p μ) :=
.symm _ _ _
-- We don't have a typeclass for additive versions of the next few lemmas
-- Should we add `AddDistribAddAction` with `to_additive` both from `MulDistribMulAction`
-- and `DistribMulAction`?
@[to_additive]
theorem smul_Lp_add (c : Mᵈᵐᵃ) : ∀ f g : Lp E p μ, c • (f + g) = c • f + c • g := by
rintro ⟨⟨⟩, _⟩ ⟨⟨⟩, _⟩; rfl
attribute [simp] DomAddAct.vadd_Lp_add
@[to_additive (attr := simp 1001)]
theorem smul_Lp_zero (c : Mᵈᵐᵃ) : c • (0 : Lp E p μ) = 0 := rfl
@[to_additive]
theorem smul_Lp_neg (c : Mᵈᵐᵃ) (f : Lp E p μ) : c • (-f) = -(c • f) := by
rcases f with ⟨⟨_⟩, _⟩; rfl
@[to_additive]
| Mathlib/MeasureTheory/Function/LpSpace/DomAct/Basic.lean | 82 | 83 | theorem smul_Lp_sub (c : Mᵈᵐᵃ) : ∀ f g : Lp E p μ, c • (f - g) = c • f - c • g := by |
rintro ⟨⟨⟩, _⟩ ⟨⟨⟩, _⟩; rfl
|
/-
Copyright (c) 2022 Joachim Breitner. All rights reserved.
Released under Apache 2.0 license as described in the file LICENSE.
Authors: Joachim Breitner
-/
import Mathlib.GroupTheory.OrderOfElement
import Mathlib.Data.Finset.NoncommProd
import Mathlib.Data.Fintype.BigOperators
import Mathlib.Data.Nat.GCD.BigOperators
import Mathlib.Order.SupIndep
#align_import group_theory.noncomm_pi_coprod from "leanprover-community/mathlib"@"6f9f36364eae3f42368b04858fd66d6d9ae730d8"
/-!
# Canonical homomorphism from a finite family of monoids
This file defines the construction of the canonical homomorphism from a family of monoids.
Given a family of morphisms `ϕ i : N i →* M` for each `i : ι` where elements in the
images of different morphisms commute, we obtain a canonical morphism
`MonoidHom.noncommPiCoprod : (Π i, N i) →* M` that coincides with `ϕ`
## Main definitions
* `MonoidHom.noncommPiCoprod : (Π i, N i) →* M` is the main homomorphism
* `Subgroup.noncommPiCoprod : (Π i, H i) →* G` is the specialization to `H i : Subgroup G`
and the subgroup embedding.
## Main theorems
* `MonoidHom.noncommPiCoprod` coincides with `ϕ i` when restricted to `N i`
* `MonoidHom.noncommPiCoprod_mrange`: The range of `MonoidHom.noncommPiCoprod` is
`⨆ (i : ι), (ϕ i).mrange`
* `MonoidHom.noncommPiCoprod_range`: The range of `MonoidHom.noncommPiCoprod` is
`⨆ (i : ι), (ϕ i).range`
* `Subgroup.noncommPiCoprod_range`: The range of `Subgroup.noncommPiCoprod` is `⨆ (i : ι), H i`.
* `MonoidHom.injective_noncommPiCoprod_of_independent`: in the case of groups, `pi_hom.hom` is
injective if the `ϕ` are injective and the ranges of the `ϕ` are independent.
* `MonoidHom.independent_range_of_coprime_order`: If the `N i` have coprime orders, then the ranges
of the `ϕ` are independent.
* `Subgroup.independent_of_coprime_order`: If commuting normal subgroups `H i` have coprime orders,
they are independent.
-/
namespace Subgroup
variable {G : Type*} [Group G]
/-- `Finset.noncommProd` is “injective” in `f` if `f` maps into independent subgroups. This
generalizes (one direction of) `Subgroup.disjoint_iff_mul_eq_one`. -/
@[to_additive "`Finset.noncommSum` is “injective” in `f` if `f` maps into independent subgroups.
This generalizes (one direction of) `AddSubgroup.disjoint_iff_add_eq_zero`. "]
| Mathlib/GroupTheory/NoncommPiCoprod.lean | 55 | 78 | theorem eq_one_of_noncommProd_eq_one_of_independent {ι : Type*} (s : Finset ι) (f : ι → G) (comm)
(K : ι → Subgroup G) (hind : CompleteLattice.Independent K) (hmem : ∀ x ∈ s, f x ∈ K x)
(heq1 : s.noncommProd f comm = 1) : ∀ i ∈ s, f i = 1 := by |
classical
revert heq1
induction' s using Finset.induction_on with i s hnmem ih
· simp
· have hcomm := comm.mono (Finset.coe_subset.2 <| Finset.subset_insert _ _)
simp only [Finset.forall_mem_insert] at hmem
have hmem_bsupr : s.noncommProd f hcomm ∈ ⨆ i ∈ (s : Set ι), K i := by
refine Subgroup.noncommProd_mem _ _ ?_
intro x hx
have : K x ≤ ⨆ i ∈ (s : Set ι), K i := le_iSup₂ (f := fun i _ => K i) x hx
exact this (hmem.2 x hx)
intro heq1
rw [Finset.noncommProd_insert_of_not_mem _ _ _ _ hnmem] at heq1
have hnmem' : i ∉ (s : Set ι) := by simpa
obtain ⟨heq1i : f i = 1, heq1S : s.noncommProd f _ = 1⟩ :=
Subgroup.disjoint_iff_mul_eq_one.mp (hind.disjoint_biSup hnmem') hmem.1 hmem_bsupr heq1
intro i h
simp only [Finset.mem_insert] at h
rcases h with (rfl | h)
· exact heq1i
· refine ih hcomm hmem.2 heq1S _ h
|
/-
Copyright (c) 2015 Microsoft Corporation. All rights reserved.
Released under Apache 2.0 license as described in the file LICENSE.
Authors: Leonardo de Moura, Jeremy Avigad, Mario Carneiro
-/
import Batteries.Tactic.Alias
import Batteries.Data.List.Init.Attach
import Batteries.Data.List.Pairwise
-- Adaptation note: nightly-2024-03-18. We should be able to remove this after nightly-2024-03-19.
import Lean.Elab.Tactic.Rfl
/-!
# List Permutations
This file introduces the `List.Perm` relation, which is true if two lists are permutations of one
another.
## Notation
The notation `~` is used for permutation equivalence.
-/
open Nat
namespace List
open Perm (swap)
@[simp, refl] protected theorem Perm.refl : ∀ l : List α, l ~ l
| [] => .nil
| x :: xs => (Perm.refl xs).cons x
protected theorem Perm.rfl {l : List α} : l ~ l := .refl _
theorem Perm.of_eq (h : l₁ = l₂) : l₁ ~ l₂ := h ▸ .rfl
protected theorem Perm.symm {l₁ l₂ : List α} (h : l₁ ~ l₂) : l₂ ~ l₁ := by
induction h with
| nil => exact nil
| cons _ _ ih => exact cons _ ih
| swap => exact swap ..
| trans _ _ ih₁ ih₂ => exact trans ih₂ ih₁
theorem perm_comm {l₁ l₂ : List α} : l₁ ~ l₂ ↔ l₂ ~ l₁ := ⟨Perm.symm, Perm.symm⟩
theorem Perm.swap' (x y : α) {l₁ l₂ : List α} (p : l₁ ~ l₂) : y :: x :: l₁ ~ x :: y :: l₂ :=
(swap ..).trans <| p.cons _ |>.cons _
/--
Similar to `Perm.recOn`, but the `swap` case is generalized to `Perm.swap'`,
where the tail of the lists are not necessarily the same.
-/
@[elab_as_elim] theorem Perm.recOnSwap'
{motive : (l₁ : List α) → (l₂ : List α) → l₁ ~ l₂ → Prop} {l₁ l₂ : List α} (p : l₁ ~ l₂)
(nil : motive [] [] .nil)
(cons : ∀ x {l₁ l₂}, (h : l₁ ~ l₂) → motive l₁ l₂ h → motive (x :: l₁) (x :: l₂) (.cons x h))
(swap' : ∀ x y {l₁ l₂}, (h : l₁ ~ l₂) → motive l₁ l₂ h →
motive (y :: x :: l₁) (x :: y :: l₂) (.swap' _ _ h))
(trans : ∀ {l₁ l₂ l₃}, (h₁ : l₁ ~ l₂) → (h₂ : l₂ ~ l₃) → motive l₁ l₂ h₁ → motive l₂ l₃ h₂ →
motive l₁ l₃ (.trans h₁ h₂)) : motive l₁ l₂ p :=
have motive_refl l : motive l l (.refl l) :=
List.recOn l nil fun x xs ih => cons x (.refl xs) ih
Perm.recOn p nil cons (fun x y l => swap' x y (.refl l) (motive_refl l)) trans
theorem Perm.eqv (α) : Equivalence (@Perm α) := ⟨.refl, .symm, .trans⟩
instance isSetoid (α) : Setoid (List α) := .mk Perm (Perm.eqv α)
theorem Perm.mem_iff {a : α} {l₁ l₂ : List α} (p : l₁ ~ l₂) : a ∈ l₁ ↔ a ∈ l₂ := by
induction p with
| nil => rfl
| cons _ _ ih => simp only [mem_cons, ih]
| swap => simp only [mem_cons, or_left_comm]
| trans _ _ ih₁ ih₂ => simp only [ih₁, ih₂]
theorem Perm.subset {l₁ l₂ : List α} (p : l₁ ~ l₂) : l₁ ⊆ l₂ := fun _ => p.mem_iff.mp
| .lake/packages/batteries/Batteries/Data/List/Perm.lean | 78 | 83 | theorem Perm.append_right {l₁ l₂ : List α} (t₁ : List α) (p : l₁ ~ l₂) : l₁ ++ t₁ ~ l₂ ++ t₁ := by |
induction p with
| nil => rfl
| cons _ _ ih => exact cons _ ih
| swap => exact swap ..
| trans _ _ ih₁ ih₂ => exact trans ih₁ ih₂
|
/-
Copyright (c) 2019 Chris Hughes. All rights reserved.
Released under Apache 2.0 license as described in the file LICENSE.
Authors: Chris Hughes, Johan Commelin
-/
import Mathlib.RingTheory.IntegralClosure
#align_import field_theory.minpoly.basic from "leanprover-community/mathlib"@"df0098f0db291900600f32070f6abb3e178be2ba"
/-!
# Minimal polynomials
This file defines the minimal polynomial of an element `x` of an `A`-algebra `B`,
under the assumption that x is integral over `A`, and derives some basic properties
such as irreducibility under the assumption `B` is a domain.
-/
open scoped Classical
open Polynomial Set Function
variable {A B B' : Type*}
section MinPolyDef
variable (A) [CommRing A] [Ring B] [Algebra A B]
/-- Suppose `x : B`, where `B` is an `A`-algebra.
The minimal polynomial `minpoly A x` of `x`
is a monic polynomial with coefficients in `A` of smallest degree that has `x` as its root,
if such exists (`IsIntegral A x`) or zero otherwise.
For example, if `V` is a `𝕜`-vector space for some field `𝕜` and `f : V →ₗ[𝕜] V` then
the minimal polynomial of `f` is `minpoly 𝕜 f`.
-/
noncomputable def minpoly (x : B) : A[X] :=
if hx : IsIntegral A x then degree_lt_wf.min _ hx else 0
#align minpoly minpoly
end MinPolyDef
namespace minpoly
section Ring
variable [CommRing A] [Ring B] [Ring B'] [Algebra A B] [Algebra A B']
variable {x : B}
/-- A minimal polynomial is monic. -/
theorem monic (hx : IsIntegral A x) : Monic (minpoly A x) := by
delta minpoly
rw [dif_pos hx]
exact (degree_lt_wf.min_mem _ hx).1
#align minpoly.monic minpoly.monic
/-- A minimal polynomial is nonzero. -/
theorem ne_zero [Nontrivial A] (hx : IsIntegral A x) : minpoly A x ≠ 0 :=
(monic hx).ne_zero
#align minpoly.ne_zero minpoly.ne_zero
theorem eq_zero (hx : ¬IsIntegral A x) : minpoly A x = 0 :=
dif_neg hx
#align minpoly.eq_zero minpoly.eq_zero
theorem algHom_eq (f : B →ₐ[A] B') (hf : Function.Injective f) (x : B) :
minpoly A (f x) = minpoly A x := by
refine dif_ctx_congr (isIntegral_algHom_iff _ hf) (fun _ => ?_) fun _ => rfl
simp_rw [← Polynomial.aeval_def, aeval_algHom, AlgHom.comp_apply, _root_.map_eq_zero_iff f hf]
#align minpoly.minpoly_alg_hom minpoly.algHom_eq
theorem algebraMap_eq {B} [CommRing B] [Algebra A B] [Algebra B B'] [IsScalarTower A B B']
(h : Function.Injective (algebraMap B B')) (x : B) :
minpoly A (algebraMap B B' x) = minpoly A x :=
algHom_eq (IsScalarTower.toAlgHom A B B') h x
@[simp]
theorem algEquiv_eq (f : B ≃ₐ[A] B') (x : B) : minpoly A (f x) = minpoly A x :=
algHom_eq (f : B →ₐ[A] B') f.injective x
#align minpoly.minpoly_alg_equiv minpoly.algEquiv_eq
variable (A x)
/-- An element is a root of its minimal polynomial. -/
@[simp]
theorem aeval : aeval x (minpoly A x) = 0 := by
delta minpoly
split_ifs with hx
· exact (degree_lt_wf.min_mem _ hx).2
· exact aeval_zero _
#align minpoly.aeval minpoly.aeval
/-- Given any `f : B →ₐ[A] B'` and any `x : L`, the minimal polynomial of `x` vanishes at `f x`. -/
@[simp]
theorem aeval_algHom (f : B →ₐ[A] B') (x : B) : (Polynomial.aeval (f x)) (minpoly A x) = 0 := by
rw [Polynomial.aeval_algHom, AlgHom.coe_comp, comp_apply, aeval, map_zero]
/-- A minimal polynomial is not `1`. -/
| Mathlib/FieldTheory/Minpoly/Basic.lean | 100 | 103 | theorem ne_one [Nontrivial B] : minpoly A x ≠ 1 := by |
intro h
refine (one_ne_zero : (1 : B) ≠ 0) ?_
simpa using congr_arg (Polynomial.aeval x) h
|
/-
Copyright (c) 2022 Yaël Dillies, Bhavik Mehta. All rights reserved.
Released under Apache 2.0 license as described in the file LICENSE.
Authors: Yaël Dillies, Bhavik Mehta
-/
import Mathlib.Algebra.Order.BigOperators.Ring.Finset
import Mathlib.Data.NNRat.Defs
/-! # Casting lemmas for non-negative rational numbers involving sums and products
-/
variable {ι α : Type*}
namespace NNRat
@[norm_cast]
theorem coe_list_sum (l : List ℚ≥0) : (l.sum : ℚ) = (l.map (↑)).sum :=
map_list_sum coeHom _
#align nnrat.coe_list_sum NNRat.coe_list_sum
@[norm_cast]
theorem coe_list_prod (l : List ℚ≥0) : (l.prod : ℚ) = (l.map (↑)).prod :=
map_list_prod coeHom _
#align nnrat.coe_list_prod NNRat.coe_list_prod
@[norm_cast]
theorem coe_multiset_sum (s : Multiset ℚ≥0) : (s.sum : ℚ) = (s.map (↑)).sum :=
map_multiset_sum coeHom _
#align nnrat.coe_multiset_sum NNRat.coe_multiset_sum
@[norm_cast]
theorem coe_multiset_prod (s : Multiset ℚ≥0) : (s.prod : ℚ) = (s.map (↑)).prod :=
map_multiset_prod coeHom _
#align nnrat.coe_multiset_prod NNRat.coe_multiset_prod
@[norm_cast]
theorem coe_sum {s : Finset α} {f : α → ℚ≥0} : ↑(∑ a ∈ s, f a) = ∑ a ∈ s, (f a : ℚ) :=
map_sum coeHom _ _
#align nnrat.coe_sum NNRat.coe_sum
theorem toNNRat_sum_of_nonneg {s : Finset α} {f : α → ℚ} (hf : ∀ a, a ∈ s → 0 ≤ f a) :
(∑ a ∈ s, f a).toNNRat = ∑ a ∈ s, (f a).toNNRat := by
rw [← coe_inj, coe_sum, Rat.coe_toNNRat _ (Finset.sum_nonneg hf)]
exact Finset.sum_congr rfl fun x hxs ↦ by rw [Rat.coe_toNNRat _ (hf x hxs)]
#align nnrat.to_nnrat_sum_of_nonneg NNRat.toNNRat_sum_of_nonneg
@[norm_cast]
theorem coe_prod {s : Finset α} {f : α → ℚ≥0} : ↑(∏ a ∈ s, f a) = ∏ a ∈ s, (f a : ℚ) :=
map_prod coeHom _ _
#align nnrat.coe_prod NNRat.coe_prod
| Mathlib/Data/NNRat/BigOperators.lean | 52 | 55 | theorem toNNRat_prod_of_nonneg {s : Finset α} {f : α → ℚ} (hf : ∀ a ∈ s, 0 ≤ f a) :
(∏ a ∈ s, f a).toNNRat = ∏ a ∈ s, (f a).toNNRat := by |
rw [← coe_inj, coe_prod, Rat.coe_toNNRat _ (Finset.prod_nonneg hf)]
exact Finset.prod_congr rfl fun x hxs ↦ by rw [Rat.coe_toNNRat _ (hf x hxs)]
|
/-
Copyright (c) 2020 Simon Hudon. All rights reserved.
Released under Apache 2.0 license as described in the file LICENSE.
Authors: Simon Hudon
-/
import Mathlib.Topology.Basic
import Mathlib.Order.UpperLower.Basic
import Mathlib.Order.OmegaCompletePartialOrder
#align_import topology.omega_complete_partial_order from "leanprover-community/mathlib"@"2705404e701abc6b3127da906f40bae062a169c9"
/-!
# Scott Topological Spaces
A type of topological spaces whose notion
of continuity is equivalent to continuity in ωCPOs.
## Reference
* https://ncatlab.org/nlab/show/Scott+topology
-/
open Set OmegaCompletePartialOrder
open scoped Classical
universe u
-- "Scott", "ωSup"
set_option linter.uppercaseLean3 false
namespace Scott
/-- `x` is an `ω`-Sup of a chain `c` if it is the least upper bound of the range of `c`. -/
def IsωSup {α : Type u} [Preorder α] (c : Chain α) (x : α) : Prop :=
(∀ i, c i ≤ x) ∧ ∀ y, (∀ i, c i ≤ y) → x ≤ y
#align Scott.is_ωSup Scott.IsωSup
theorem isωSup_iff_isLUB {α : Type u} [Preorder α] {c : Chain α} {x : α} :
IsωSup c x ↔ IsLUB (range c) x := by
simp [IsωSup, IsLUB, IsLeast, upperBounds, lowerBounds]
#align Scott.is_ωSup_iff_is_lub Scott.isωSup_iff_isLUB
variable (α : Type u) [OmegaCompletePartialOrder α]
/-- The characteristic function of open sets is monotone and preserves
the limits of chains. -/
def IsOpen (s : Set α) : Prop :=
Continuous' fun x ↦ x ∈ s
#align Scott.is_open Scott.IsOpen
theorem isOpen_univ : IsOpen α univ :=
⟨fun _ _ _ _ ↦ mem_univ _, @CompleteLattice.top_continuous α Prop _ _⟩
#align Scott.is_open_univ Scott.isOpen_univ
theorem IsOpen.inter (s t : Set α) : IsOpen α s → IsOpen α t → IsOpen α (s ∩ t) :=
CompleteLattice.inf_continuous'
#align Scott.is_open.inter Scott.IsOpen.inter
theorem isOpen_sUnion (s : Set (Set α)) (hs : ∀ t ∈ s, IsOpen α t) : IsOpen α (⋃₀ s) := by
simp only [IsOpen] at hs ⊢
convert CompleteLattice.sSup_continuous' (setOf ⁻¹' s) hs
simp only [sSup_apply, setOf_bijective.surjective.exists, exists_prop, mem_preimage,
SetCoe.exists, iSup_Prop_eq, mem_setOf_eq, mem_sUnion]
#align Scott.is_open_sUnion Scott.isOpen_sUnion
theorem IsOpen.isUpperSet {s : Set α} (hs : IsOpen α s) : IsUpperSet s := hs.fst
end Scott
/-- A Scott topological space is defined on preorders
such that their open sets, seen as a function `α → Prop`,
preserves the joins of ω-chains -/
abbrev Scott (α : Type u) := α
#align Scott Scott
instance Scott.topologicalSpace (α : Type u) [OmegaCompletePartialOrder α] :
TopologicalSpace (Scott α) where
IsOpen := Scott.IsOpen α
isOpen_univ := Scott.isOpen_univ α
isOpen_inter := Scott.IsOpen.inter α
isOpen_sUnion := Scott.isOpen_sUnion α
#align Scott.topological_space Scott.topologicalSpace
section notBelow
variable {α : Type*} [OmegaCompletePartialOrder α] (y : Scott α)
/-- `notBelow` is an open set in `Scott α` used
to prove the monotonicity of continuous functions -/
def notBelow :=
{ x | ¬x ≤ y }
#align not_below notBelow
theorem notBelow_isOpen : IsOpen (notBelow y) := by
have h : Monotone (notBelow y) := fun x z hle ↦ mt hle.trans
refine ⟨h, fun c ↦ eq_of_forall_ge_iff fun z ↦ ?_⟩
simp only [ωSup_le_iff, notBelow, mem_setOf_eq, le_Prop_eq, OrderHom.coe_mk, Chain.map_coe,
Function.comp_apply, exists_imp, not_forall]
#align not_below_is_open notBelow_isOpen
end notBelow
open Scott hiding IsOpen
open OmegaCompletePartialOrder
| Mathlib/Topology/OmegaCompletePartialOrder.lean | 110 | 113 | theorem isωSup_ωSup {α} [OmegaCompletePartialOrder α] (c : Chain α) : IsωSup c (ωSup c) := by |
constructor
· apply le_ωSup
· apply ωSup_le
|
/-
Copyright (c) 2022 Yaël Dillies, Bhavik Mehta. All rights reserved.
Released under Apache 2.0 license as described in the file LICENSE.
Authors: Yaël Dillies, Bhavik Mehta
-/
import Mathlib.Analysis.InnerProductSpace.PiL2
import Mathlib.Combinatorics.Additive.AP.Three.Defs
import Mathlib.Combinatorics.Pigeonhole
import Mathlib.Data.Complex.ExponentialBounds
#align_import combinatorics.additive.behrend from "leanprover-community/mathlib"@"4fa54b337f7d52805480306db1b1439c741848c8"
/-!
# Behrend's bound on Roth numbers
This file proves Behrend's lower bound on Roth numbers. This says that we can find a subset of
`{1, ..., n}` of size `n / exp (O (sqrt (log n)))` which does not contain arithmetic progressions of
length `3`.
The idea is that the sphere (in the `n` dimensional Euclidean space) doesn't contain arithmetic
progressions (literally) because the corresponding ball is strictly convex. Thus we can take
integer points on that sphere and map them onto `ℕ` in a way that preserves arithmetic progressions
(`Behrend.map`).
## Main declarations
* `Behrend.sphere`: The intersection of the Euclidean sphere with the positive integer quadrant.
This is the set that we will map on `ℕ`.
* `Behrend.map`: Given a natural number `d`, `Behrend.map d : ℕⁿ → ℕ` reads off the coordinates as
digits in base `d`.
* `Behrend.card_sphere_le_rothNumberNat`: Implicit lower bound on Roth numbers in terms of
`Behrend.sphere`.
* `Behrend.roth_lower_bound`: Behrend's explicit lower bound on Roth numbers.
## References
* [Bryan Gillespie, *Behrend’s Construction*]
(http://www.epsilonsmall.com/resources/behrends-construction/behrend.pdf)
* Behrend, F. A., "On sets of integers which contain no three terms in arithmetical progression"
* [Wikipedia, *Salem-Spencer set*](https://en.wikipedia.org/wiki/Salem–Spencer_set)
## Tags
3AP-free, Salem-Spencer, Behrend construction, arithmetic progression, sphere, strictly convex
-/
open Nat hiding log
open Finset Metric Real
open scoped Pointwise
/-- The frontier of a closed strictly convex set only contains trivial arithmetic progressions.
The idea is that an arithmetic progression is contained on a line and the frontier of a strictly
convex set does not contain lines. -/
lemma threeAPFree_frontier {𝕜 E : Type*} [LinearOrderedField 𝕜] [TopologicalSpace E]
[AddCommMonoid E] [Module 𝕜 E] {s : Set E} (hs₀ : IsClosed s) (hs₁ : StrictConvex 𝕜 s) :
ThreeAPFree (frontier s) := by
intro a ha b hb c hc habc
obtain rfl : (1 / 2 : 𝕜) • a + (1 / 2 : 𝕜) • c = b := by
rwa [← smul_add, one_div, inv_smul_eq_iff₀ (show (2 : 𝕜) ≠ 0 by norm_num), two_smul]
have :=
hs₁.eq (hs₀.frontier_subset ha) (hs₀.frontier_subset hc) one_half_pos one_half_pos
(add_halves _) hb.2
simp [this, ← add_smul]
ring_nf
simp
#align add_salem_spencer_frontier threeAPFree_frontier
lemma threeAPFree_sphere {E : Type*} [NormedAddCommGroup E] [NormedSpace ℝ E]
[StrictConvexSpace ℝ E] (x : E) (r : ℝ) : ThreeAPFree (sphere x r) := by
obtain rfl | hr := eq_or_ne r 0
· rw [sphere_zero]
exact threeAPFree_singleton _
· convert threeAPFree_frontier isClosed_ball (strictConvex_closedBall ℝ x r)
exact (frontier_closedBall _ hr).symm
#align add_salem_spencer_sphere threeAPFree_sphere
namespace Behrend
variable {α β : Type*} {n d k N : ℕ} {x : Fin n → ℕ}
/-!
### Turning the sphere into 3AP-free set
We define `Behrend.sphere`, the intersection of the $L^2$ sphere with the positive quadrant of
integer points. Because the $L^2$ closed ball is strictly convex, the $L^2$ sphere and
`Behrend.sphere` are 3AP-free (`threeAPFree_sphere`). Then we can turn this set in
`Fin n → ℕ` into a set in `ℕ` using `Behrend.map`, which preserves `ThreeAPFree` because it is
an additive monoid homomorphism.
-/
/-- The box `{0, ..., d - 1}^n` as a `Finset`. -/
def box (n d : ℕ) : Finset (Fin n → ℕ) :=
Fintype.piFinset fun _ => range d
#align behrend.box Behrend.box
theorem mem_box : x ∈ box n d ↔ ∀ i, x i < d := by simp only [box, Fintype.mem_piFinset, mem_range]
#align behrend.mem_box Behrend.mem_box
@[simp]
theorem card_box : (box n d).card = d ^ n := by simp [box]
#align behrend.card_box Behrend.card_box
@[simp]
theorem box_zero : box (n + 1) 0 = ∅ := by simp [box]
#align behrend.box_zero Behrend.box_zero
/-- The intersection of the sphere of radius `√k` with the integer points in the positive
quadrant. -/
def sphere (n d k : ℕ) : Finset (Fin n → ℕ) :=
(box n d).filter fun x => ∑ i, x i ^ 2 = k
#align behrend.sphere Behrend.sphere
theorem sphere_zero_subset : sphere n d 0 ⊆ 0 := fun x => by simp [sphere, Function.funext_iff]
#align behrend.sphere_zero_subset Behrend.sphere_zero_subset
@[simp]
| Mathlib/Combinatorics/Additive/AP/Three/Behrend.lean | 118 | 118 | theorem sphere_zero_right (n k : ℕ) : sphere (n + 1) 0 k = ∅ := by | simp [sphere]
|
/-
Copyright (c) 2020 Yury G. Kudryashov. All rights reserved.
Released under Apache 2.0 license as described in the file LICENSE.
Authors: Yury G. Kudryashov
-/
import Mathlib.Algebra.Group.Pi.Lemmas
import Mathlib.Topology.Algebra.Monoid
import Mathlib.Topology.Homeomorph
#align_import topology.algebra.group_with_zero from "leanprover-community/mathlib"@"c10e724be91096453ee3db13862b9fb9a992fef2"
/-!
# Topological group with zero
In this file we define `HasContinuousInv₀` to be a mixin typeclass a type with `Inv` and
`Zero` (e.g., a `GroupWithZero`) such that `fun x ↦ x⁻¹` is continuous at all nonzero points. Any
normed (semi)field has this property. Currently the only example of `HasContinuousInv₀` in
`mathlib` which is not a normed field is the type `NNReal` (a.k.a. `ℝ≥0`) of nonnegative real
numbers.
Then we prove lemmas about continuity of `x ↦ x⁻¹` and `f / g` providing dot-style `*.inv₀` and
`*.div` operations on `Filter.Tendsto`, `ContinuousAt`, `ContinuousWithinAt`, `ContinuousOn`,
and `Continuous`. As a special case, we provide `*.div_const` operations that require only
`DivInvMonoid` and `ContinuousMul` instances.
All lemmas about `(⁻¹)` use `inv₀` in their names because lemmas without `₀` are used for
`TopologicalGroup`s. We also use `'` in the typeclass name `HasContinuousInv₀` for the sake of
consistency of notation.
On a `GroupWithZero` with continuous multiplication, we also define left and right multiplication
as homeomorphisms.
-/
open Topology Filter Function
/-!
### A `DivInvMonoid` with continuous multiplication
If `G₀` is a `DivInvMonoid` with continuous `(*)`, then `(/y)` is continuous for any `y`. In this
section we prove lemmas that immediately follow from this fact providing `*.div_const` dot-style
operations on `Filter.Tendsto`, `ContinuousAt`, `ContinuousWithinAt`, `ContinuousOn`, and
`Continuous`.
-/
variable {α β G₀ : Type*}
section DivConst
variable [DivInvMonoid G₀] [TopologicalSpace G₀] [ContinuousMul G₀] {f : α → G₀} {s : Set α}
{l : Filter α}
theorem Filter.Tendsto.div_const {x : G₀} (hf : Tendsto f l (𝓝 x)) (y : G₀) :
Tendsto (fun a => f a / y) l (𝓝 (x / y)) := by
simpa only [div_eq_mul_inv] using hf.mul tendsto_const_nhds
#align filter.tendsto.div_const Filter.Tendsto.div_const
variable [TopologicalSpace α]
nonrec theorem ContinuousAt.div_const {a : α} (hf : ContinuousAt f a) (y : G₀) :
ContinuousAt (fun x => f x / y) a :=
hf.div_const y
#align continuous_at.div_const ContinuousAt.div_const
nonrec theorem ContinuousWithinAt.div_const {a} (hf : ContinuousWithinAt f s a) (y : G₀) :
ContinuousWithinAt (fun x => f x / y) s a :=
hf.div_const _
#align continuous_within_at.div_const ContinuousWithinAt.div_const
| Mathlib/Topology/Algebra/GroupWithZero.lean | 69 | 71 | theorem ContinuousOn.div_const (hf : ContinuousOn f s) (y : G₀) :
ContinuousOn (fun x => f x / y) s := by |
simpa only [div_eq_mul_inv] using hf.mul continuousOn_const
|
/-
Copyright (c) 2019 Johan Commelin. All rights reserved.
Released under Apache 2.0 license as described in the file LICENSE.
Authors: Johan Commelin
-/
import Mathlib.Algebra.Order.Group.Nat
import Mathlib.Data.Finset.Antidiagonal
import Mathlib.Data.Finset.Card
import Mathlib.Data.Multiset.NatAntidiagonal
#align_import data.finset.nat_antidiagonal from "leanprover-community/mathlib"@"9003f28797c0664a49e4179487267c494477d853"
/-!
# Antidiagonals in ℕ × ℕ as finsets
This file defines the antidiagonals of ℕ × ℕ as finsets: the `n`-th antidiagonal is the finset of
pairs `(i, j)` such that `i + j = n`. This is useful for polynomial multiplication and more
generally for sums going from `0` to `n`.
## Notes
This refines files `Data.List.NatAntidiagonal` and `Data.Multiset.NatAntidiagonal`, providing an
instance enabling `Finset.antidiagonal` on `Nat`.
-/
open Function
namespace Finset
namespace Nat
/-- The antidiagonal of a natural number `n` is
the finset of pairs `(i, j)` such that `i + j = n`. -/
instance instHasAntidiagonal : HasAntidiagonal ℕ where
antidiagonal n := ⟨Multiset.Nat.antidiagonal n, Multiset.Nat.nodup_antidiagonal n⟩
mem_antidiagonal {n} {xy} := by
rw [mem_def, Multiset.Nat.mem_antidiagonal]
lemma antidiagonal_eq_map (n : ℕ) :
antidiagonal n = (range (n + 1)).map ⟨fun i ↦ (i, n - i), fun _ _ h ↦ (Prod.ext_iff.1 h).1⟩ :=
rfl
lemma antidiagonal_eq_map' (n : ℕ) :
antidiagonal n =
(range (n + 1)).map ⟨fun i ↦ (n - i, i), fun _ _ h ↦ (Prod.ext_iff.1 h).2⟩ := by
rw [← map_swap_antidiagonal, antidiagonal_eq_map, map_map]; rfl
lemma antidiagonal_eq_image (n : ℕ) :
antidiagonal n = (range (n + 1)).image fun i ↦ (i, n - i) := by
simp only [antidiagonal_eq_map, map_eq_image, Function.Embedding.coeFn_mk]
lemma antidiagonal_eq_image' (n : ℕ) :
antidiagonal n = (range (n + 1)).image fun i ↦ (n - i, i) := by
simp only [antidiagonal_eq_map', map_eq_image, Function.Embedding.coeFn_mk]
/-- The cardinality of the antidiagonal of `n` is `n + 1`. -/
@[simp]
theorem card_antidiagonal (n : ℕ) : (antidiagonal n).card = n + 1 := by simp [antidiagonal]
#align finset.nat.card_antidiagonal Finset.Nat.card_antidiagonal
/-- The antidiagonal of `0` is the list `[(0, 0)]` -/
-- nolint as this is for dsimp
@[simp, nolint simpNF]
theorem antidiagonal_zero : antidiagonal 0 = {(0, 0)} := rfl
#align finset.nat.antidiagonal_zero Finset.Nat.antidiagonal_zero
theorem antidiagonal_succ (n : ℕ) :
antidiagonal (n + 1) =
cons (0, n + 1)
((antidiagonal n).map
(Embedding.prodMap ⟨Nat.succ, Nat.succ_injective⟩ (Embedding.refl _)))
(by simp) := by
apply eq_of_veq
rw [cons_val, map_val]
apply Multiset.Nat.antidiagonal_succ
#align finset.nat.antidiagonal_succ Finset.Nat.antidiagonal_succ
theorem antidiagonal_succ' (n : ℕ) :
antidiagonal (n + 1) =
cons (n + 1, 0)
((antidiagonal n).map
(Embedding.prodMap (Embedding.refl _) ⟨Nat.succ, Nat.succ_injective⟩))
(by simp) := by
apply eq_of_veq
rw [cons_val, map_val]
exact Multiset.Nat.antidiagonal_succ'
#align finset.nat.antidiagonal_succ' Finset.Nat.antidiagonal_succ'
| Mathlib/Data/Finset/NatAntidiagonal.lean | 89 | 99 | theorem antidiagonal_succ_succ' {n : ℕ} :
antidiagonal (n + 2) =
cons (0, n + 2)
(cons (n + 2, 0)
((antidiagonal n).map
(Embedding.prodMap ⟨Nat.succ, Nat.succ_injective⟩
⟨Nat.succ, Nat.succ_injective⟩)) <|
by simp)
(by simp) := by |
simp_rw [antidiagonal_succ (n + 1), antidiagonal_succ', Finset.map_cons, map_map]
rfl
|
/-
Copyright (c) 2021 Joël Riou. All rights reserved.
Released under Apache 2.0 license as described in the file LICENSE.
Authors: Joël Riou, Adam Topaz, Johan Commelin
-/
import Mathlib.Algebra.Homology.Additive
import Mathlib.AlgebraicTopology.MooreComplex
import Mathlib.Algebra.BigOperators.Fin
import Mathlib.CategoryTheory.Preadditive.Opposite
import Mathlib.CategoryTheory.Idempotents.FunctorCategories
#align_import algebraic_topology.alternating_face_map_complex from "leanprover-community/mathlib"@"88bca0ce5d22ebfd9e73e682e51d60ea13b48347"
/-!
# The alternating face map complex of a simplicial object in a preadditive category
We construct the alternating face map complex, as a
functor `alternatingFaceMapComplex : SimplicialObject C ⥤ ChainComplex C ℕ`
for any preadditive category `C`. For any simplicial object `X` in `C`,
this is the homological complex `... → X_2 → X_1 → X_0`
where the differentials are alternating sums of faces.
The dual version `alternatingCofaceMapComplex : CosimplicialObject C ⥤ CochainComplex C ℕ`
is also constructed.
We also construct the natural transformation
`inclusionOfMooreComplex : normalizedMooreComplex A ⟶ alternatingFaceMapComplex A`
when `A` is an abelian category.
## References
* https://stacks.math.columbia.edu/tag/0194
* https://ncatlab.org/nlab/show/Moore+complex
-/
open CategoryTheory CategoryTheory.Limits CategoryTheory.Subobject
open CategoryTheory.Preadditive CategoryTheory.Category CategoryTheory.Idempotents
open Opposite
open Simplicial
noncomputable section
namespace AlgebraicTopology
namespace AlternatingFaceMapComplex
/-!
## Construction of the alternating face map complex
-/
variable {C : Type*} [Category C] [Preadditive C]
variable (X : SimplicialObject C)
variable (Y : SimplicialObject C)
/-- The differential on the alternating face map complex is the alternate
sum of the face maps -/
@[simp]
def objD (n : ℕ) : X _[n + 1] ⟶ X _[n] :=
∑ i : Fin (n + 2), (-1 : ℤ) ^ (i : ℕ) • X.δ i
#align algebraic_topology.alternating_face_map_complex.obj_d AlgebraicTopology.AlternatingFaceMapComplex.objD
/-- ## The chain complex relation `d ≫ d`
-/
| Mathlib/AlgebraicTopology/AlternatingFaceMapComplex.lean | 70 | 112 | theorem d_squared (n : ℕ) : objD X (n + 1) ≫ objD X n = 0 := by |
-- we start by expanding d ≫ d as a double sum
dsimp
simp only [comp_sum, sum_comp, ← Finset.sum_product']
-- then, we decompose the index set P into a subset S and its complement Sᶜ
let P := Fin (n + 2) × Fin (n + 3)
let S := Finset.univ.filter fun ij : P => (ij.2 : ℕ) ≤ (ij.1 : ℕ)
erw [← Finset.sum_add_sum_compl S, ← eq_neg_iff_add_eq_zero, ← Finset.sum_neg_distrib]
/- we are reduced to showing that two sums are equal, and this is obtained
by constructing a bijection φ : S -> Sᶜ, which maps (i,j) to (j,i+1),
and by comparing the terms -/
let φ : ∀ ij : P, ij ∈ S → P := fun ij hij =>
(Fin.castLT ij.2 (lt_of_le_of_lt (Finset.mem_filter.mp hij).right (Fin.is_lt ij.1)), ij.1.succ)
apply Finset.sum_bij φ
· -- φ(S) is contained in Sᶜ
intro ij hij
simp only [S, Finset.mem_univ, Finset.compl_filter, Finset.mem_filter, true_and_iff,
Fin.val_succ, Fin.coe_castLT] at hij ⊢
linarith
· -- φ : S → Sᶜ is injective
rintro ⟨i, j⟩ hij ⟨i', j'⟩ hij' h
rw [Prod.mk.inj_iff]
exact ⟨by simpa using congr_arg Prod.snd h,
by simpa [Fin.castSucc_castLT] using congr_arg Fin.castSucc (congr_arg Prod.fst h)⟩
· -- φ : S → Sᶜ is surjective
rintro ⟨i', j'⟩ hij'
simp only [S, Finset.mem_univ, forall_true_left, Prod.forall, ge_iff_le, Finset.compl_filter,
not_le, Finset.mem_filter, true_and] at hij'
refine ⟨(j'.pred <| ?_, Fin.castSucc i'), ?_, ?_⟩
· rintro rfl
simp only [Fin.val_zero, not_lt_zero'] at hij'
· simpa only [S, Finset.mem_univ, forall_true_left, Prod.forall, ge_iff_le, Finset.mem_filter,
Fin.coe_castSucc, Fin.coe_pred, true_and] using Nat.le_sub_one_of_lt hij'
· simp only [φ, Fin.castLT_castSucc, Fin.succ_pred]
· -- identification of corresponding terms in both sums
rintro ⟨i, j⟩ hij
dsimp
simp only [zsmul_comp, comp_zsmul, smul_smul, ← neg_smul]
congr 1
· simp only [Fin.val_succ, pow_add, pow_one, mul_neg, neg_neg, mul_one]
apply mul_comm
· rw [CategoryTheory.SimplicialObject.δ_comp_δ'']
simpa [S] using hij
|
/-
Copyright (c) 2020 Floris van Doorn. All rights reserved.
Released under Apache 2.0 license as described in the file LICENSE.
Authors: Floris van Doorn, Yaël Dillies
-/
import Mathlib.Topology.Sets.Opens
#align_import topology.sets.closeds from "leanprover-community/mathlib"@"dc6c365e751e34d100e80fe6e314c3c3e0fd2988"
/-!
# Closed sets
We define a few types of closed sets in a topological space.
## Main Definitions
For a topological space `α`,
* `TopologicalSpace.Closeds α`: The type of closed sets.
* `TopologicalSpace.Clopens α`: The type of clopen sets.
-/
open Order OrderDual Set
variable {ι α β : Type*} [TopologicalSpace α] [TopologicalSpace β]
namespace TopologicalSpace
/-! ### Closed sets -/
/-- The type of closed subsets of a topological space. -/
structure Closeds (α : Type*) [TopologicalSpace α] where
/-- the carrier set, i.e. the points in this set -/
carrier : Set α
closed' : IsClosed carrier
#align topological_space.closeds TopologicalSpace.Closeds
namespace Closeds
instance : SetLike (Closeds α) α where
coe := Closeds.carrier
coe_injective' s t h := by cases s; cases t; congr
instance : CanLift (Set α) (Closeds α) (↑) IsClosed where
prf s hs := ⟨⟨s, hs⟩, rfl⟩
theorem closed (s : Closeds α) : IsClosed (s : Set α) :=
s.closed'
#align topological_space.closeds.closed TopologicalSpace.Closeds.closed
/-- See Note [custom simps projection]. -/
def Simps.coe (s : Closeds α) : Set α := s
initialize_simps_projections Closeds (carrier → coe, as_prefix coe)
@[ext]
protected theorem ext {s t : Closeds α} (h : (s : Set α) = t) : s = t :=
SetLike.ext' h
#align topological_space.closeds.ext TopologicalSpace.Closeds.ext
@[simp]
theorem coe_mk (s : Set α) (h) : (mk s h : Set α) = s :=
rfl
#align topological_space.closeds.coe_mk TopologicalSpace.Closeds.coe_mk
/-- The closure of a set, as an element of `TopologicalSpace.Closeds`. -/
@[simps]
protected def closure (s : Set α) : Closeds α :=
⟨closure s, isClosed_closure⟩
#align topological_space.closeds.closure TopologicalSpace.Closeds.closure
theorem gc : GaloisConnection Closeds.closure ((↑) : Closeds α → Set α) := fun _ U =>
⟨subset_closure.trans, fun h => closure_minimal h U.closed⟩
#align topological_space.closeds.gc TopologicalSpace.Closeds.gc
/-- The galois coinsertion between sets and opens. -/
def gi : GaloisInsertion (@Closeds.closure α _) (↑) where
choice s hs := ⟨s, closure_eq_iff_isClosed.1 <| hs.antisymm subset_closure⟩
gc := gc
le_l_u _ := subset_closure
choice_eq _s hs := SetLike.coe_injective <| subset_closure.antisymm hs
#align topological_space.closeds.gi TopologicalSpace.Closeds.gi
instance completeLattice : CompleteLattice (Closeds α) :=
CompleteLattice.copy
(GaloisInsertion.liftCompleteLattice gi)
-- le
_ rfl
-- top
⟨univ, isClosed_univ⟩ rfl
-- bot
⟨∅, isClosed_empty⟩ (SetLike.coe_injective closure_empty.symm)
-- sup
(fun s t => ⟨s ∪ t, s.2.union t.2⟩)
(funext fun s => funext fun t => SetLike.coe_injective (s.2.union t.2).closure_eq.symm)
-- inf
(fun s t => ⟨s ∩ t, s.2.inter t.2⟩) rfl
-- sSup
_ rfl
-- sInf
(fun S => ⟨⋂ s ∈ S, ↑s, isClosed_biInter fun s _ => s.2⟩)
(funext fun _ => SetLike.coe_injective sInf_image.symm)
/-- The type of closed sets is inhabited, with default element the empty set. -/
instance : Inhabited (Closeds α) :=
⟨⊥⟩
@[simp, norm_cast]
| Mathlib/Topology/Sets/Closeds.lean | 110 | 111 | theorem coe_sup (s t : Closeds α) : (↑(s ⊔ t) : Set α) = ↑s ∪ ↑t := by |
rfl
|
/-
Copyright (c) 2020 Aaron Anderson, Jalex Stark, Kyle Miller. All rights reserved.
Released under Apache 2.0 license as described in the file LICENSE.
Authors: Aaron Anderson, Jalex Stark, Kyle Miller, Alena Gusakov
-/
import Mathlib.Algebra.Order.Ring.Defs
import Mathlib.Combinatorics.SimpleGraph.Basic
import Mathlib.Data.Sym.Card
/-!
# Definitions for finite and locally finite graphs
This file defines finite versions of `edgeSet`, `neighborSet` and `incidenceSet` and proves some
of their basic properties. It also defines the notion of a locally finite graph, which is one
whose vertices have finite degree.
The design for finiteness is that each definition takes the smallest finiteness assumption
necessary. For example, `SimpleGraph.neighborFinset v` only requires that `v` have
finitely many neighbors.
## Main definitions
* `SimpleGraph.edgeFinset` is the `Finset` of edges in a graph, if `edgeSet` is finite
* `SimpleGraph.neighborFinset` is the `Finset` of vertices adjacent to a given vertex,
if `neighborSet` is finite
* `SimpleGraph.incidenceFinset` is the `Finset` of edges containing a given vertex,
if `incidenceSet` is finite
## Naming conventions
If the vertex type of a graph is finite, we refer to its cardinality as `CardVerts`
or `card_verts`.
## Implementation notes
* A locally finite graph is one with instances `Π v, Fintype (G.neighborSet v)`.
* Given instances `DecidableRel G.Adj` and `Fintype V`, then the graph
is locally finite, too.
-/
open Finset Function
namespace SimpleGraph
variable {V : Type*} (G : SimpleGraph V) {e : Sym2 V}
section EdgeFinset
variable {G₁ G₂ : SimpleGraph V} [Fintype G.edgeSet] [Fintype G₁.edgeSet] [Fintype G₂.edgeSet]
/-- The `edgeSet` of the graph as a `Finset`. -/
abbrev edgeFinset : Finset (Sym2 V) :=
Set.toFinset G.edgeSet
#align simple_graph.edge_finset SimpleGraph.edgeFinset
@[norm_cast]
theorem coe_edgeFinset : (G.edgeFinset : Set (Sym2 V)) = G.edgeSet :=
Set.coe_toFinset _
#align simple_graph.coe_edge_finset SimpleGraph.coe_edgeFinset
variable {G}
theorem mem_edgeFinset : e ∈ G.edgeFinset ↔ e ∈ G.edgeSet :=
Set.mem_toFinset
#align simple_graph.mem_edge_finset SimpleGraph.mem_edgeFinset
theorem not_isDiag_of_mem_edgeFinset : e ∈ G.edgeFinset → ¬e.IsDiag :=
not_isDiag_of_mem_edgeSet _ ∘ mem_edgeFinset.1
#align simple_graph.not_is_diag_of_mem_edge_finset SimpleGraph.not_isDiag_of_mem_edgeFinset
theorem edgeFinset_inj : G₁.edgeFinset = G₂.edgeFinset ↔ G₁ = G₂ := by simp
#align simple_graph.edge_finset_inj SimpleGraph.edgeFinset_inj
theorem edgeFinset_subset_edgeFinset : G₁.edgeFinset ⊆ G₂.edgeFinset ↔ G₁ ≤ G₂ := by simp
#align simple_graph.edge_finset_subset_edge_finset SimpleGraph.edgeFinset_subset_edgeFinset
theorem edgeFinset_ssubset_edgeFinset : G₁.edgeFinset ⊂ G₂.edgeFinset ↔ G₁ < G₂ := by simp
#align simple_graph.edge_finset_ssubset_edge_finset SimpleGraph.edgeFinset_ssubset_edgeFinset
@[gcongr] alias ⟨_, edgeFinset_mono⟩ := edgeFinset_subset_edgeFinset
#align simple_graph.edge_finset_mono SimpleGraph.edgeFinset_mono
alias ⟨_, edgeFinset_strict_mono⟩ := edgeFinset_ssubset_edgeFinset
#align simple_graph.edge_finset_strict_mono SimpleGraph.edgeFinset_strict_mono
attribute [mono] edgeFinset_mono edgeFinset_strict_mono
@[simp]
theorem edgeFinset_bot : (⊥ : SimpleGraph V).edgeFinset = ∅ := by simp [edgeFinset]
#align simple_graph.edge_finset_bot SimpleGraph.edgeFinset_bot
@[simp]
theorem edgeFinset_sup [Fintype (edgeSet (G₁ ⊔ G₂))] [DecidableEq V] :
(G₁ ⊔ G₂).edgeFinset = G₁.edgeFinset ∪ G₂.edgeFinset := by simp [edgeFinset]
#align simple_graph.edge_finset_sup SimpleGraph.edgeFinset_sup
@[simp]
theorem edgeFinset_inf [DecidableEq V] : (G₁ ⊓ G₂).edgeFinset = G₁.edgeFinset ∩ G₂.edgeFinset := by
simp [edgeFinset]
#align simple_graph.edge_finset_inf SimpleGraph.edgeFinset_inf
@[simp]
theorem edgeFinset_sdiff [DecidableEq V] :
(G₁ \ G₂).edgeFinset = G₁.edgeFinset \ G₂.edgeFinset := by simp [edgeFinset]
#align simple_graph.edge_finset_sdiff SimpleGraph.edgeFinset_sdiff
theorem edgeFinset_card : G.edgeFinset.card = Fintype.card G.edgeSet :=
Set.toFinset_card _
#align simple_graph.edge_finset_card SimpleGraph.edgeFinset_card
@[simp]
theorem edgeSet_univ_card : (univ : Finset G.edgeSet).card = G.edgeFinset.card :=
Fintype.card_of_subtype G.edgeFinset fun _ => mem_edgeFinset
#align simple_graph.edge_set_univ_card SimpleGraph.edgeSet_univ_card
variable [Fintype V]
@[simp]
theorem edgeFinset_top [DecidableEq V] :
(⊤ : SimpleGraph V).edgeFinset = univ.filter fun e => ¬e.IsDiag := by
rw [← coe_inj]; simp
/-- The complete graph on `n` vertices has `n.choose 2` edges. -/
| Mathlib/Combinatorics/SimpleGraph/Finite.lean | 125 | 127 | theorem card_edgeFinset_top_eq_card_choose_two [DecidableEq V] :
(⊤ : SimpleGraph V).edgeFinset.card = (Fintype.card V).choose 2 := by |
simp_rw [Set.toFinset_card, edgeSet_top, Set.coe_setOf, ← Sym2.card_subtype_not_diag]
|
/-
Copyright (c) 2022 Tian Chen. All rights reserved.
Released under Apache 2.0 license as described in the file LICENSE.
Authors: Tian Chen, Mantas Bakšys
-/
import Mathlib.Algebra.GeomSum
import Mathlib.Algebra.Order.Ring.Basic
import Mathlib.Algebra.Ring.Int
import Mathlib.NumberTheory.Padics.PadicVal
import Mathlib.RingTheory.Ideal.Quotient
#align_import number_theory.multiplicity from "leanprover-community/mathlib"@"e8638a0fcaf73e4500469f368ef9494e495099b3"
/-!
# Multiplicity in Number Theory
This file contains results in number theory relating to multiplicity.
## Main statements
* `multiplicity.Int.pow_sub_pow` is the lifting the exponent lemma for odd primes.
We also prove several variations of the lemma.
## References
* [Wikipedia, *Lifting-the-exponent lemma*]
(https://en.wikipedia.org/wiki/Lifting-the-exponent_lemma)
-/
open Ideal Ideal.Quotient Finset
variable {R : Type*} {n : ℕ}
section CommRing
variable [CommRing R] {a b x y : R}
theorem dvd_geom_sum₂_iff_of_dvd_sub {x y p : R} (h : p ∣ x - y) :
(p ∣ ∑ i ∈ range n, x ^ i * y ^ (n - 1 - i)) ↔ p ∣ n * y ^ (n - 1) := by
rw [← mem_span_singleton, ← Ideal.Quotient.eq] at h
simp only [← mem_span_singleton, ← eq_zero_iff_mem, RingHom.map_geom_sum₂, h, geom_sum₂_self,
_root_.map_mul, map_pow, map_natCast]
#align dvd_geom_sum₂_iff_of_dvd_sub dvd_geom_sum₂_iff_of_dvd_sub
theorem dvd_geom_sum₂_iff_of_dvd_sub' {x y p : R} (h : p ∣ x - y) :
(p ∣ ∑ i ∈ range n, x ^ i * y ^ (n - 1 - i)) ↔ p ∣ n * x ^ (n - 1) := by
rw [geom_sum₂_comm, dvd_geom_sum₂_iff_of_dvd_sub]; simpa using h.neg_right
#align dvd_geom_sum₂_iff_of_dvd_sub' dvd_geom_sum₂_iff_of_dvd_sub'
theorem dvd_geom_sum₂_self {x y : R} (h : ↑n ∣ x - y) :
↑n ∣ ∑ i ∈ range n, x ^ i * y ^ (n - 1 - i) :=
(dvd_geom_sum₂_iff_of_dvd_sub h).mpr (dvd_mul_right _ _)
#align dvd_geom_sum₂_self dvd_geom_sum₂_self
| Mathlib/NumberTheory/Multiplicity.lean | 56 | 71 | theorem sq_dvd_add_pow_sub_sub (p x : R) (n : ℕ) :
p ^ 2 ∣ (x + p) ^ n - x ^ (n - 1) * p * n - x ^ n := by |
cases' n with n n
· simp only [pow_zero, Nat.cast_zero, sub_zero, sub_self, dvd_zero, Nat.zero_eq, mul_zero]
· simp only [Nat.succ_sub_succ_eq_sub, tsub_zero, Nat.cast_succ, add_pow, Finset.sum_range_succ,
Nat.choose_self, Nat.succ_sub _, tsub_self, pow_one, Nat.choose_succ_self_right, pow_zero,
mul_one, Nat.cast_zero, zero_add, Nat.succ_eq_add_one, add_tsub_cancel_left]
suffices p ^ 2 ∣ ∑ i ∈ range n, x ^ i * p ^ (n + 1 - i) * ↑((n + 1).choose i) by
convert this; abel
apply Finset.dvd_sum
intro y hy
calc
p ^ 2 ∣ p ^ (n + 1 - y) :=
pow_dvd_pow p (le_tsub_of_add_le_left (by linarith [Finset.mem_range.mp hy]))
_ ∣ x ^ y * p ^ (n + 1 - y) * ↑((n + 1).choose y) :=
dvd_mul_of_dvd_left (dvd_mul_left _ _) _
|
/-
Copyright (c) 2024 Jz Pan. All rights reserved.
Released under Apache 2.0 license as described in the file LICENSE.
Authors: Jz Pan
-/
import Mathlib.Algebra.Polynomial.RingDivision
import Mathlib.RingTheory.Polynomial.Nilpotent
/-!
# Polynomials over an irreducible ring
This file contains results about the polynomials over an irreducible ring (i.e. a ring with only
one minimal prime ideal, equivalently, whose spectrum is an irreducible topological space).
## Main results
- `Polynomial.Monic.irreducible_of_irreducible_map_of_isPrime_nilradical`: a monic polynomial over
an irreducible ring is irreducible if it is irreducible after mapping into an integral domain.
A generalization to `Polynomial.Monic.irreducible_of_irreducible_map`.
## Tags
polynomial, irreducible ring, nilradical, prime ideal
-/
open scoped Classical Polynomial
open Polynomial
noncomputable section
/-- A polynomial over an irreducible ring `R` is irreducible if it is monic and irreducible after
mapping into an integral domain `S` (https://math.stackexchange.com/a/4843432/235999).
A generalization to `Polynomial.Monic.irreducible_of_irreducible_map`. -/
| Mathlib/RingTheory/Polynomial/IrreducibleRing.lean | 37 | 61 | theorem Polynomial.Monic.irreducible_of_irreducible_map_of_isPrime_nilradical
{R S : Type*} [CommRing R] [(nilradical R).IsPrime] [CommRing S] [IsDomain S]
(φ : R →+* S) (f : R[X]) (hm : f.Monic) (hi : Irreducible (f.map φ)) : Irreducible f := by |
let R' := R ⧸ nilradical R
let ψ : R' →+* S := Ideal.Quotient.lift (nilradical R) φ
(haveI := RingHom.ker_isPrime φ; nilradical_le_prime (RingHom.ker φ))
let ι := algebraMap R R'
rw [show φ = ψ.comp ι from rfl, ← map_map] at hi
replace hi := hm.map ι |>.irreducible_of_irreducible_map _ _ hi
refine ⟨fun h ↦ hi.1 <| (mapRingHom ι).isUnit_map h, fun a b h ↦ ?_⟩
wlog hb : IsUnit (b.map ι) generalizing a b
· exact (this b a (mul_comm a b ▸ h)
(hi.2 _ _ (by rw [h, Polynomial.map_mul]) |>.resolve_right hb)).symm
have hn (i : ℕ) (hi : i ≠ 0) : IsNilpotent (b.coeff i) := by
obtain ⟨_, _, h⟩ := Polynomial.isUnit_iff.1 hb
simpa only [coeff_map, coeff_C, hi, ite_false, ← RingHom.mem_ker,
show RingHom.ker ι = nilradical R from Ideal.mk_ker] using congr(coeff $(h.symm) i)
refine .inr <| isUnit_of_coeff_isUnit_isNilpotent (isUnit_of_mul_isUnit_right
(x := a.coeff f.natDegree) <| (IsUnit.neg_iff _).1 ?_) hn
have hc : f.leadingCoeff = _ := congr(coeff $h f.natDegree)
rw [hm, coeff_mul, Finset.Nat.sum_antidiagonal_eq_sum_range_succ fun i j ↦ a.coeff i * b.coeff j,
Finset.sum_range_succ, ← sub_eq_iff_eq_add, Nat.sub_self] at hc
rw [← add_sub_cancel_left 1 (-(_ * _)), ← sub_eq_add_neg, hc]
exact IsNilpotent.isUnit_sub_one <| show _ ∈ nilradical R from sum_mem fun i hi ↦
Ideal.mul_mem_left _ _ <| hn _ <| Nat.sub_ne_zero_of_lt (List.mem_range.1 hi)
|
/-
Copyright (c) 2021 Alex J. Best. All rights reserved.
Released under Apache 2.0 license as described in the file LICENSE.
Authors: Alex J. Best, Yaël Dillies
-/
import Mathlib.Algebra.Bounds
import Mathlib.Algebra.Order.Field.Basic -- Porting note: `LinearOrderedField`, etc
import Mathlib.Data.Set.Pointwise.SMul
#align_import algebra.order.pointwise from "leanprover-community/mathlib"@"9003f28797c0664a49e4179487267c494477d853"
/-!
# Pointwise operations on ordered algebraic objects
This file contains lemmas about the effect of pointwise operations on sets with an order structure.
## TODO
`sSup (s • t) = sSup s • sSup t` and `sInf (s • t) = sInf s • sInf t` hold as well but
`CovariantClass` is currently not polymorphic enough to state it.
-/
open Function Set
open Pointwise
variable {α : Type*}
-- Porting note: Swapped the place of `CompleteLattice` and `ConditionallyCompleteLattice`
-- due to simpNF problem between `sSup_xx` `csSup_xx`.
section CompleteLattice
variable [CompleteLattice α]
section One
variable [One α]
@[to_additive (attr := simp)]
theorem sSup_one : sSup (1 : Set α) = 1 :=
sSup_singleton
#align Sup_zero sSup_zero
#align Sup_one sSup_one
@[to_additive (attr := simp)]
theorem sInf_one : sInf (1 : Set α) = 1 :=
sInf_singleton
#align Inf_zero sInf_zero
#align Inf_one sInf_one
end One
section Group
variable [Group α] [CovariantClass α α (· * ·) (· ≤ ·)] [CovariantClass α α (swap (· * ·)) (· ≤ ·)]
(s t : Set α)
@[to_additive]
theorem sSup_inv (s : Set α) : sSup s⁻¹ = (sInf s)⁻¹ := by
rw [← image_inv, sSup_image]
exact ((OrderIso.inv α).map_sInf _).symm
#align Sup_inv sSup_inv
#align Sup_neg sSup_neg
@[to_additive]
theorem sInf_inv (s : Set α) : sInf s⁻¹ = (sSup s)⁻¹ := by
rw [← image_inv, sInf_image]
exact ((OrderIso.inv α).map_sSup _).symm
#align Inf_inv sInf_inv
#align Inf_neg sInf_neg
@[to_additive]
theorem sSup_mul : sSup (s * t) = sSup s * sSup t :=
(sSup_image2_eq_sSup_sSup fun _ => (OrderIso.mulRight _).to_galoisConnection) fun _ =>
(OrderIso.mulLeft _).to_galoisConnection
#align Sup_mul sSup_mul
#align Sup_add sSup_add
@[to_additive]
theorem sInf_mul : sInf (s * t) = sInf s * sInf t :=
(sInf_image2_eq_sInf_sInf fun _ => (OrderIso.mulRight _).symm.to_galoisConnection) fun _ =>
(OrderIso.mulLeft _).symm.to_galoisConnection
#align Inf_mul sInf_mul
#align Inf_add sInf_add
@[to_additive]
theorem sSup_div : sSup (s / t) = sSup s / sInf t := by simp_rw [div_eq_mul_inv, sSup_mul, sSup_inv]
#align Sup_div sSup_div
#align Sup_sub sSup_sub
@[to_additive]
theorem sInf_div : sInf (s / t) = sInf s / sSup t := by simp_rw [div_eq_mul_inv, sInf_mul, sInf_inv]
#align Inf_div sInf_div
#align Inf_sub sInf_sub
end Group
end CompleteLattice
section ConditionallyCompleteLattice
variable [ConditionallyCompleteLattice α]
section One
variable [One α]
@[to_additive (attr := simp)]
theorem csSup_one : sSup (1 : Set α) = 1 :=
csSup_singleton _
#align cSup_zero csSup_zero
#align cSup_one csSup_one
@[to_additive (attr := simp)]
theorem csInf_one : sInf (1 : Set α) = 1 :=
csInf_singleton _
#align cInf_zero csInf_zero
#align cInf_one csInf_one
end One
section Group
variable [Group α] [CovariantClass α α (· * ·) (· ≤ ·)] [CovariantClass α α (swap (· * ·)) (· ≤ ·)]
{s t : Set α}
@[to_additive]
theorem csSup_inv (hs₀ : s.Nonempty) (hs₁ : BddBelow s) : sSup s⁻¹ = (sInf s)⁻¹ := by
rw [← image_inv]
exact ((OrderIso.inv α).map_csInf' hs₀ hs₁).symm
#align cSup_inv csSup_inv
#align cSup_neg csSup_neg
@[to_additive]
theorem csInf_inv (hs₀ : s.Nonempty) (hs₁ : BddAbove s) : sInf s⁻¹ = (sSup s)⁻¹ := by
rw [← image_inv]
exact ((OrderIso.inv α).map_csSup' hs₀ hs₁).symm
#align cInf_inv csInf_inv
#align cInf_neg csInf_neg
@[to_additive]
theorem csSup_mul (hs₀ : s.Nonempty) (hs₁ : BddAbove s) (ht₀ : t.Nonempty) (ht₁ : BddAbove t) :
sSup (s * t) = sSup s * sSup t :=
csSup_image2_eq_csSup_csSup (fun _ => (OrderIso.mulRight _).to_galoisConnection)
(fun _ => (OrderIso.mulLeft _).to_galoisConnection) hs₀ hs₁ ht₀ ht₁
#align cSup_mul csSup_mul
#align cSup_add csSup_add
@[to_additive]
theorem csInf_mul (hs₀ : s.Nonempty) (hs₁ : BddBelow s) (ht₀ : t.Nonempty) (ht₁ : BddBelow t) :
sInf (s * t) = sInf s * sInf t :=
csInf_image2_eq_csInf_csInf (fun _ => (OrderIso.mulRight _).symm.to_galoisConnection)
(fun _ => (OrderIso.mulLeft _).symm.to_galoisConnection) hs₀ hs₁ ht₀ ht₁
#align cInf_mul csInf_mul
#align cInf_add csInf_add
@[to_additive]
| Mathlib/Algebra/Order/Pointwise.lean | 160 | 162 | theorem csSup_div (hs₀ : s.Nonempty) (hs₁ : BddAbove s) (ht₀ : t.Nonempty) (ht₁ : BddBelow t) :
sSup (s / t) = sSup s / sInf t := by |
rw [div_eq_mul_inv, csSup_mul hs₀ hs₁ ht₀.inv ht₁.inv, csSup_inv ht₀ ht₁, div_eq_mul_inv]
|
/-
Copyright (c) 2017 Johannes Hölzl. All rights reserved.
Released under Apache 2.0 license as described in the file LICENSE.
Authors: Johannes Hölzl, Mario Carneiro
-/
import Mathlib.MeasureTheory.Measure.Restrict
/-!
# Classes of measures
We introduce the following typeclasses for measures:
* `IsProbabilityMeasure μ`: `μ univ = 1`;
* `IsFiniteMeasure μ`: `μ univ < ∞`;
* `SigmaFinite μ`: there exists a countable collection of sets that cover `univ`
where `μ` is finite;
* `SFinite μ`: the measure `μ` can be written as a countable sum of finite measures;
* `IsLocallyFiniteMeasure μ` : `∀ x, ∃ s ∈ 𝓝 x, μ s < ∞`;
* `NoAtoms μ` : `∀ x, μ {x} = 0`; possibly should be redefined as
`∀ s, 0 < μ s → ∃ t ⊆ s, 0 < μ t ∧ μ t < μ s`.
-/
open scoped ENNReal NNReal Topology
open Set MeasureTheory Measure Filter Function MeasurableSpace ENNReal
variable {α β δ ι : Type*}
namespace MeasureTheory
variable {m0 : MeasurableSpace α} [MeasurableSpace β] {μ ν ν₁ ν₂: Measure α}
{s t : Set α}
section IsFiniteMeasure
/-- A measure `μ` is called finite if `μ univ < ∞`. -/
class IsFiniteMeasure (μ : Measure α) : Prop where
measure_univ_lt_top : μ univ < ∞
#align measure_theory.is_finite_measure MeasureTheory.IsFiniteMeasure
#align measure_theory.is_finite_measure.measure_univ_lt_top MeasureTheory.IsFiniteMeasure.measure_univ_lt_top
| Mathlib/MeasureTheory/Measure/Typeclasses.lean | 41 | 44 | theorem not_isFiniteMeasure_iff : ¬IsFiniteMeasure μ ↔ μ Set.univ = ∞ := by |
refine ⟨fun h => ?_, fun h => fun h' => h'.measure_univ_lt_top.ne h⟩
by_contra h'
exact h ⟨lt_top_iff_ne_top.mpr h'⟩
|
/-
Copyright (c) 2022 Eric Wieser. All rights reserved.
Released under Apache 2.0 license as described in the file LICENSE.
Authors: Eric Wieser
-/
import Mathlib.LinearAlgebra.CliffordAlgebra.Conjugation
#align_import linear_algebra.clifford_algebra.fold from "leanprover-community/mathlib"@"446eb51ce0a90f8385f260d2b52e760e2004246b"
/-!
# Recursive computation rules for the Clifford algebra
This file provides API for a special case `CliffordAlgebra.foldr` of the universal property
`CliffordAlgebra.lift` with `A = Module.End R N` for some arbitrary module `N`. This specialization
resembles the `list.foldr` operation, allowing a bilinear map to be "folded" along the generators.
For convenience, this file also provides `CliffordAlgebra.foldl`, implemented via
`CliffordAlgebra.reverse`
## Main definitions
* `CliffordAlgebra.foldr`: a computation rule for building linear maps out of the clifford
algebra starting on the right, analogous to using `list.foldr` on the generators.
* `CliffordAlgebra.foldl`: a computation rule for building linear maps out of the clifford
algebra starting on the left, analogous to using `list.foldl` on the generators.
## Main statements
* `CliffordAlgebra.right_induction`: an induction rule that adds generators from the right.
* `CliffordAlgebra.left_induction`: an induction rule that adds generators from the left.
-/
universe u1 u2 u3
variable {R M N : Type*}
variable [CommRing R] [AddCommGroup M] [AddCommGroup N]
variable [Module R M] [Module R N]
variable (Q : QuadraticForm R M)
namespace CliffordAlgebra
section Foldr
/-- Fold a bilinear map along the generators of a term of the clifford algebra, with the rule
given by `foldr Q f hf n (ι Q m * x) = f m (foldr Q f hf n x)`.
For example, `foldr f hf n (r • ι R u + ι R v * ι R w) = r • f u n + f v (f w n)`. -/
def foldr (f : M →ₗ[R] N →ₗ[R] N) (hf : ∀ m x, f m (f m x) = Q m • x) :
N →ₗ[R] CliffordAlgebra Q →ₗ[R] N :=
(CliffordAlgebra.lift Q ⟨f, fun v => LinearMap.ext <| hf v⟩).toLinearMap.flip
#align clifford_algebra.foldr CliffordAlgebra.foldr
@[simp]
theorem foldr_ι (f : M →ₗ[R] N →ₗ[R] N) (hf) (n : N) (m : M) : foldr Q f hf n (ι Q m) = f m n :=
LinearMap.congr_fun (lift_ι_apply _ _ _) n
#align clifford_algebra.foldr_ι CliffordAlgebra.foldr_ι
@[simp]
theorem foldr_algebraMap (f : M →ₗ[R] N →ₗ[R] N) (hf) (n : N) (r : R) :
foldr Q f hf n (algebraMap R _ r) = r • n :=
LinearMap.congr_fun (AlgHom.commutes _ r) n
#align clifford_algebra.foldr_algebra_map CliffordAlgebra.foldr_algebraMap
@[simp]
theorem foldr_one (f : M →ₗ[R] N →ₗ[R] N) (hf) (n : N) : foldr Q f hf n 1 = n :=
LinearMap.congr_fun (AlgHom.map_one _) n
#align clifford_algebra.foldr_one CliffordAlgebra.foldr_one
@[simp]
theorem foldr_mul (f : M →ₗ[R] N →ₗ[R] N) (hf) (n : N) (a b : CliffordAlgebra Q) :
foldr Q f hf n (a * b) = foldr Q f hf (foldr Q f hf n b) a :=
LinearMap.congr_fun (AlgHom.map_mul _ _ _) n
#align clifford_algebra.foldr_mul CliffordAlgebra.foldr_mul
/-- This lemma demonstrates the origin of the `foldr` name. -/
theorem foldr_prod_map_ι (l : List M) (f : M →ₗ[R] N →ₗ[R] N) (hf) (n : N) :
foldr Q f hf n (l.map <| ι Q).prod = List.foldr (fun m n => f m n) n l := by
induction' l with hd tl ih
· rw [List.map_nil, List.prod_nil, List.foldr_nil, foldr_one]
· rw [List.map_cons, List.prod_cons, List.foldr_cons, foldr_mul, foldr_ι, ih]
#align clifford_algebra.foldr_prod_map_ι CliffordAlgebra.foldr_prod_map_ι
end Foldr
section Foldl
/-- Fold a bilinear map along the generators of a term of the clifford algebra, with the rule
given by `foldl Q f hf n (ι Q m * x) = f m (foldl Q f hf n x)`.
For example, `foldl f hf n (r • ι R u + ι R v * ι R w) = r • f u n + f v (f w n)`. -/
def foldl (f : M →ₗ[R] N →ₗ[R] N) (hf : ∀ m x, f m (f m x) = Q m • x) :
N →ₗ[R] CliffordAlgebra Q →ₗ[R] N :=
LinearMap.compl₂ (foldr Q f hf) reverse
#align clifford_algebra.foldl CliffordAlgebra.foldl
@[simp]
theorem foldl_reverse (f : M →ₗ[R] N →ₗ[R] N) (hf) (n : N) (x : CliffordAlgebra Q) :
foldl Q f hf n (reverse x) = foldr Q f hf n x :=
DFunLike.congr_arg (foldr Q f hf n) <| reverse_reverse _
#align clifford_algebra.foldl_reverse CliffordAlgebra.foldl_reverse
@[simp]
theorem foldr_reverse (f : M →ₗ[R] N →ₗ[R] N) (hf) (n : N) (x : CliffordAlgebra Q) :
foldr Q f hf n (reverse x) = foldl Q f hf n x :=
rfl
#align clifford_algebra.foldr_reverse CliffordAlgebra.foldr_reverse
@[simp]
theorem foldl_ι (f : M →ₗ[R] N →ₗ[R] N) (hf) (n : N) (m : M) : foldl Q f hf n (ι Q m) = f m n := by
rw [← foldr_reverse, reverse_ι, foldr_ι]
#align clifford_algebra.foldl_ι CliffordAlgebra.foldl_ι
@[simp]
| Mathlib/LinearAlgebra/CliffordAlgebra/Fold.lean | 115 | 117 | theorem foldl_algebraMap (f : M →ₗ[R] N →ₗ[R] N) (hf) (n : N) (r : R) :
foldl Q f hf n (algebraMap R _ r) = r • n := by |
rw [← foldr_reverse, reverse.commutes, foldr_algebraMap]
|
/-
Copyright (c) 2022 Antoine Labelle. All rights reserved.
Released under Apache 2.0 license as described in the file LICENSE.
Authors: Antoine Labelle
-/
import Mathlib.RepresentationTheory.FdRep
import Mathlib.LinearAlgebra.Trace
import Mathlib.RepresentationTheory.Invariants
#align_import representation_theory.character from "leanprover-community/mathlib"@"55b3f8206b8596db8bb1804d8a92814a0b6670c9"
/-!
# Characters of representations
This file introduces characters of representation and proves basic lemmas about how characters
behave under various operations on representations.
A key result is the orthogonality of characters for irreducible representations of finite group
over an algebraically closed field whose characteristic doesn't divide the order of the group. It
is the theorem `char_orthonormal`
# Implementation notes
Irreducible representations are implemented categorically, using the `Simple` class defined in
`Mathlib.CategoryTheory.Simple`
# TODO
* Once we have the monoidal closed structure on `FdRep k G` and a better API for the rigid
structure, `char_dual` and `char_linHom` should probably be stated in terms of `Vᘁ` and `ihom V W`.
-/
noncomputable section
universe u
open CategoryTheory LinearMap CategoryTheory.MonoidalCategory Representation FiniteDimensional
variable {k : Type u} [Field k]
namespace FdRep
set_option linter.uppercaseLean3 false -- `FdRep`
section Monoid
variable {G : Type u} [Monoid G]
/-- The character of a representation `V : FdRep k G` is the function associating to `g : G` the
trace of the linear map `V.ρ g`. -/
def character (V : FdRep k G) (g : G) :=
LinearMap.trace k V (V.ρ g)
#align fdRep.character FdRep.character
theorem char_mul_comm (V : FdRep k G) (g : G) (h : G) :
V.character (h * g) = V.character (g * h) := by simp only [trace_mul_comm, character, map_mul]
#align fdRep.char_mul_comm FdRep.char_mul_comm
@[simp]
theorem char_one (V : FdRep k G) : V.character 1 = FiniteDimensional.finrank k V := by
simp only [character, map_one, trace_one]
#align fdRep.char_one FdRep.char_one
/-- The character is multiplicative under the tensor product. -/
theorem char_tensor (V W : FdRep k G) : (V ⊗ W).character = V.character * W.character := by
ext g; convert trace_tensorProduct' (V.ρ g) (W.ρ g)
#align fdRep.char_tensor FdRep.char_tensor
-- Porting note: adding variant of `char_tensor` to make the simp-set confluent
@[simp]
theorem char_tensor' (V W : FdRep k G) :
character (Action.FunctorCategoryEquivalence.inverse.obj
(Action.FunctorCategoryEquivalence.functor.obj V ⊗
Action.FunctorCategoryEquivalence.functor.obj W)) = V.character * W.character := by
simp [← char_tensor]
/-- The character of isomorphic representations is the same. -/
theorem char_iso {V W : FdRep k G} (i : V ≅ W) : V.character = W.character := by
ext g; simp only [character, FdRep.Iso.conj_ρ i]; exact (trace_conj' (V.ρ g) _).symm
#align fdRep.char_iso FdRep.char_iso
end Monoid
section Group
variable {G : Type u} [Group G]
/-- The character of a representation is constant on conjugacy classes. -/
@[simp]
theorem char_conj (V : FdRep k G) (g : G) (h : G) : V.character (h * g * h⁻¹) = V.character g := by
rw [char_mul_comm, inv_mul_cancel_left]
#align fdRep.char_conj FdRep.char_conj
@[simp]
theorem char_dual (V : FdRep k G) (g : G) : (of (dual V.ρ)).character g = V.character g⁻¹ :=
trace_transpose' (V.ρ g⁻¹)
#align fdRep.char_dual FdRep.char_dual
@[simp]
theorem char_linHom (V W : FdRep k G) (g : G) :
(of (linHom V.ρ W.ρ)).character g = V.character g⁻¹ * W.character g := by
rw [← char_iso (dualTensorIsoLinHom _ _), char_tensor, Pi.mul_apply, char_dual]
#align fdRep.char_lin_hom FdRep.char_linHom
variable [Fintype G] [Invertible (Fintype.card G : k)]
| Mathlib/RepresentationTheory/Character.lean | 106 | 109 | theorem average_char_eq_finrank_invariants (V : FdRep k G) :
⅟ (Fintype.card G : k) • ∑ g : G, V.character g = finrank k (invariants V.ρ) := by |
erw [← (isProj_averageMap V.ρ).trace] -- Porting note: Changed `rw` to `erw`
simp [character, GroupAlgebra.average, _root_.map_sum]
|
/-
Copyright (c) 2022 Tian Chen. All rights reserved.
Released under Apache 2.0 license as described in the file LICENSE.
Authors: Tian Chen, Mantas Bakšys
-/
import Mathlib.Algebra.GeomSum
import Mathlib.Algebra.Order.Ring.Basic
import Mathlib.Algebra.Ring.Int
import Mathlib.NumberTheory.Padics.PadicVal
import Mathlib.RingTheory.Ideal.Quotient
#align_import number_theory.multiplicity from "leanprover-community/mathlib"@"e8638a0fcaf73e4500469f368ef9494e495099b3"
/-!
# Multiplicity in Number Theory
This file contains results in number theory relating to multiplicity.
## Main statements
* `multiplicity.Int.pow_sub_pow` is the lifting the exponent lemma for odd primes.
We also prove several variations of the lemma.
## References
* [Wikipedia, *Lifting-the-exponent lemma*]
(https://en.wikipedia.org/wiki/Lifting-the-exponent_lemma)
-/
open Ideal Ideal.Quotient Finset
variable {R : Type*} {n : ℕ}
section CommRing
variable [CommRing R] {a b x y : R}
| Mathlib/NumberTheory/Multiplicity.lean | 39 | 43 | theorem dvd_geom_sum₂_iff_of_dvd_sub {x y p : R} (h : p ∣ x - y) :
(p ∣ ∑ i ∈ range n, x ^ i * y ^ (n - 1 - i)) ↔ p ∣ n * y ^ (n - 1) := by |
rw [← mem_span_singleton, ← Ideal.Quotient.eq] at h
simp only [← mem_span_singleton, ← eq_zero_iff_mem, RingHom.map_geom_sum₂, h, geom_sum₂_self,
_root_.map_mul, map_pow, map_natCast]
|
/-
Copyright (c) 2015 Microsoft Corporation. All rights reserved.
Released under Apache 2.0 license as described in the file LICENSE.
Authors: Leonardo de Moura, Mario Carneiro
-/
import Mathlib.Algebra.Group.Prod
import Mathlib.Data.Set.Lattice
#align_import data.nat.pairing from "leanprover-community/mathlib"@"207cfac9fcd06138865b5d04f7091e46d9320432"
/-!
# Naturals pairing function
This file defines a pairing function for the naturals as follows:
```text
0 1 4 9 16
2 3 5 10 17
6 7 8 11 18
12 13 14 15 19
20 21 22 23 24
```
It has the advantage of being monotone in both directions and sending `⟦0, n^2 - 1⟧` to
`⟦0, n - 1⟧²`.
-/
assert_not_exists MonoidWithZero
open Prod Decidable Function
namespace Nat
/-- Pairing function for the natural numbers. -/
-- Porting note: no pp_nodot
--@[pp_nodot]
def pair (a b : ℕ) : ℕ :=
if a < b then b * b + a else a * a + a + b
#align nat.mkpair Nat.pair
/-- Unpairing function for the natural numbers. -/
-- Porting note: no pp_nodot
--@[pp_nodot]
def unpair (n : ℕ) : ℕ × ℕ :=
let s := sqrt n
if n - s * s < s then (n - s * s, s) else (s, n - s * s - s)
#align nat.unpair Nat.unpair
@[simp]
theorem pair_unpair (n : ℕ) : pair (unpair n).1 (unpair n).2 = n := by
dsimp only [unpair]; let s := sqrt n
have sm : s * s + (n - s * s) = n := Nat.add_sub_cancel' (sqrt_le _)
split_ifs with h
· simp [pair, h, sm]
· have hl : n - s * s - s ≤ s := Nat.sub_le_iff_le_add.2
(Nat.sub_le_iff_le_add'.2 <| by rw [← Nat.add_assoc]; apply sqrt_le_add)
simp [pair, hl.not_lt, Nat.add_assoc, Nat.add_sub_cancel' (le_of_not_gt h), sm]
#align nat.mkpair_unpair Nat.pair_unpair
theorem pair_unpair' {n a b} (H : unpair n = (a, b)) : pair a b = n := by
simpa [H] using pair_unpair n
#align nat.mkpair_unpair' Nat.pair_unpair'
@[simp]
| Mathlib/Data/Nat/Pairing.lean | 64 | 73 | theorem unpair_pair (a b : ℕ) : unpair (pair a b) = (a, b) := by |
dsimp only [pair]; split_ifs with h
· show unpair (b * b + a) = (a, b)
have be : sqrt (b * b + a) = b := sqrt_add_eq _ (le_trans (le_of_lt h) (Nat.le_add_left _ _))
simp [unpair, be, Nat.add_sub_cancel_left, h]
· show unpair (a * a + a + b) = (a, b)
have ae : sqrt (a * a + (a + b)) = a := by
rw [sqrt_add_eq]
exact Nat.add_le_add_left (le_of_not_gt h) _
simp [unpair, ae, Nat.not_lt_zero, Nat.add_assoc, Nat.add_sub_cancel_left]
|
/-
Copyright (c) 2017 Johannes Hölzl. All rights reserved.
Released under Apache 2.0 license as described in the file LICENSE.
Authors: Johannes Hölzl
-/
import Mathlib.Algebra.BigOperators.NatAntidiagonal
import Mathlib.Topology.Algebra.InfiniteSum.Constructions
import Mathlib.Topology.Algebra.Ring.Basic
#align_import topology.algebra.infinite_sum.ring from "leanprover-community/mathlib"@"9a59dcb7a2d06bf55da57b9030169219980660cd"
/-!
# Infinite sum in a ring
This file provides lemmas about the interaction between infinite sums and multiplication.
## Main results
* `tsum_mul_tsum_eq_tsum_sum_antidiagonal`: Cauchy product formula
-/
open Filter Finset Function
open scoped Classical
variable {ι κ R α : Type*}
section NonUnitalNonAssocSemiring
variable [NonUnitalNonAssocSemiring α] [TopologicalSpace α] [TopologicalSemiring α] {f g : ι → α}
{a a₁ a₂ : α}
theorem HasSum.mul_left (a₂) (h : HasSum f a₁) : HasSum (fun i ↦ a₂ * f i) (a₂ * a₁) := by
simpa only using h.map (AddMonoidHom.mulLeft a₂) (continuous_const.mul continuous_id)
#align has_sum.mul_left HasSum.mul_left
| Mathlib/Topology/Algebra/InfiniteSum/Ring.lean | 38 | 39 | theorem HasSum.mul_right (a₂) (hf : HasSum f a₁) : HasSum (fun i ↦ f i * a₂) (a₁ * a₂) := by |
simpa only using hf.map (AddMonoidHom.mulRight a₂) (continuous_id.mul continuous_const)
|
/-
Copyright (c) 2022 Anatole Dedecker. All rights reserved.
Released under Apache 2.0 license as described in the file LICENSE.
Authors: Moritz Doll, Frédéric Dupuis, Heather Macbeth
-/
import Mathlib.Analysis.InnerProductSpace.Basic
import Mathlib.Analysis.NormedSpace.Banach
import Mathlib.LinearAlgebra.SesquilinearForm
#align_import analysis.inner_product_space.symmetric from "leanprover-community/mathlib"@"3f655f5297b030a87d641ad4e825af8d9679eb0b"
/-!
# Symmetric linear maps in an inner product space
This file defines and proves basic theorems about symmetric **not necessarily bounded** operators
on an inner product space, i.e linear maps `T : E → E` such that `∀ x y, ⟪T x, y⟫ = ⟪x, T y⟫`.
In comparison to `IsSelfAdjoint`, this definition works for non-continuous linear maps, and
doesn't rely on the definition of the adjoint, which allows it to be stated in non-complete space.
## Main definitions
* `LinearMap.IsSymmetric`: a (not necessarily bounded) operator on an inner product space is
symmetric, if for all `x`, `y`, we have `⟪T x, y⟫ = ⟪x, T y⟫`
## Main statements
* `IsSymmetric.continuous`: if a symmetric operator is defined on a complete space, then
it is automatically continuous.
## Tags
self-adjoint, symmetric
-/
open RCLike
open ComplexConjugate
variable {𝕜 E E' F G : Type*} [RCLike 𝕜]
variable [NormedAddCommGroup E] [InnerProductSpace 𝕜 E]
variable [NormedAddCommGroup F] [InnerProductSpace 𝕜 F]
variable [NormedAddCommGroup G] [InnerProductSpace 𝕜 G]
variable [NormedAddCommGroup E'] [InnerProductSpace ℝ E']
local notation "⟪" x ", " y "⟫" => @inner 𝕜 _ _ x y
namespace LinearMap
/-! ### Symmetric operators -/
/-- A (not necessarily bounded) operator on an inner product space is symmetric, if for all
`x`, `y`, we have `⟪T x, y⟫ = ⟪x, T y⟫`. -/
def IsSymmetric (T : E →ₗ[𝕜] E) : Prop :=
∀ x y, ⟪T x, y⟫ = ⟪x, T y⟫
#align linear_map.is_symmetric LinearMap.IsSymmetric
section Real
/-- An operator `T` on an inner product space is symmetric if and only if it is
`LinearMap.IsSelfAdjoint` with respect to the sesquilinear form given by the inner product. -/
theorem isSymmetric_iff_sesqForm (T : E →ₗ[𝕜] E) :
T.IsSymmetric ↔ LinearMap.IsSelfAdjoint (R := 𝕜) (M := E) sesqFormOfInner T :=
⟨fun h x y => (h y x).symm, fun h x y => (h y x).symm⟩
#align linear_map.is_symmetric_iff_sesq_form LinearMap.isSymmetric_iff_sesqForm
end Real
theorem IsSymmetric.conj_inner_sym {T : E →ₗ[𝕜] E} (hT : IsSymmetric T) (x y : E) :
conj ⟪T x, y⟫ = ⟪T y, x⟫ := by rw [hT x y, inner_conj_symm]
#align linear_map.is_symmetric.conj_inner_sym LinearMap.IsSymmetric.conj_inner_sym
@[simp]
theorem IsSymmetric.apply_clm {T : E →L[𝕜] E} (hT : IsSymmetric (T : E →ₗ[𝕜] E)) (x y : E) :
⟪T x, y⟫ = ⟪x, T y⟫ :=
hT x y
#align linear_map.is_symmetric.apply_clm LinearMap.IsSymmetric.apply_clm
theorem isSymmetric_zero : (0 : E →ₗ[𝕜] E).IsSymmetric := fun x y =>
(inner_zero_right x : ⟪x, 0⟫ = 0).symm ▸ (inner_zero_left y : ⟪0, y⟫ = 0)
#align linear_map.is_symmetric_zero LinearMap.isSymmetric_zero
theorem isSymmetric_id : (LinearMap.id : E →ₗ[𝕜] E).IsSymmetric := fun _ _ => rfl
#align linear_map.is_symmetric_id LinearMap.isSymmetric_id
theorem IsSymmetric.add {T S : E →ₗ[𝕜] E} (hT : T.IsSymmetric) (hS : S.IsSymmetric) :
(T + S).IsSymmetric := by
intro x y
rw [LinearMap.add_apply, inner_add_left, hT x y, hS x y, ← inner_add_right]
rfl
#align linear_map.is_symmetric.add LinearMap.IsSymmetric.add
/-- The **Hellinger--Toeplitz theorem**: if a symmetric operator is defined on a complete space,
then it is automatically continuous. -/
| Mathlib/Analysis/InnerProductSpace/Symmetric.lean | 97 | 110 | theorem IsSymmetric.continuous [CompleteSpace E] {T : E →ₗ[𝕜] E} (hT : IsSymmetric T) :
Continuous T := by |
-- We prove it by using the closed graph theorem
refine T.continuous_of_seq_closed_graph fun u x y hu hTu => ?_
rw [← sub_eq_zero, ← @inner_self_eq_zero 𝕜]
have hlhs : ∀ k : ℕ, ⟪T (u k) - T x, y - T x⟫ = ⟪u k - x, T (y - T x)⟫ := by
intro k
rw [← T.map_sub, hT]
refine tendsto_nhds_unique ((hTu.sub_const _).inner tendsto_const_nhds) ?_
simp_rw [Function.comp_apply, hlhs]
rw [← inner_zero_left (T (y - T x))]
refine Filter.Tendsto.inner ?_ tendsto_const_nhds
rw [← sub_self x]
exact hu.sub_const _
|
/-
Copyright (c) 2019 Chris Hughes. All rights reserved.
Released under Apache 2.0 license as described in the file LICENSE.
Authors: Chris Hughes
-/
import Mathlib.Data.Matrix.Basic
import Mathlib.Data.PEquiv
#align_import data.matrix.pequiv from "leanprover-community/mathlib"@"3e068ece210655b7b9a9477c3aff38a492400aa1"
/-!
# partial equivalences for matrices
Using partial equivalences to represent matrices.
This file introduces the function `PEquiv.toMatrix`, which returns a matrix containing ones and
zeros. For any partial equivalence `f`, `f.toMatrix i j = 1 ↔ f i = some j`.
The following important properties of this function are proved
`toMatrix_trans : (f.trans g).toMatrix = f.toMatrix * g.toMatrix`
`toMatrix_symm : f.symm.toMatrix = f.toMatrixᵀ`
`toMatrix_refl : (PEquiv.refl n).toMatrix = 1`
`toMatrix_bot : ⊥.toMatrix = 0`
This theory gives the matrix representation of projection linear maps, and their right inverses.
For example, the matrix `(single (0 : Fin 1) (i : Fin n)).toMatrix` corresponds to the ith
projection map from R^n to R.
Any injective function `Fin m → Fin n` gives rise to a `PEquiv`, whose matrix is the projection
map from R^m → R^n represented by the same function. The transpose of this matrix is the right
inverse of this map, sending anything not in the image to zero.
## notations
This file uses `ᵀ` for `Matrix.transpose`.
-/
namespace PEquiv
open Matrix
universe u v
variable {k l m n : Type*}
variable {α : Type v}
open Matrix
/-- `toMatrix` returns a matrix containing ones and zeros. `f.toMatrix i j` is `1` if
`f i = some j` and `0` otherwise -/
def toMatrix [DecidableEq n] [Zero α] [One α] (f : m ≃. n) : Matrix m n α :=
of fun i j => if j ∈ f i then (1 : α) else 0
#align pequiv.to_matrix PEquiv.toMatrix
-- TODO: set as an equation lemma for `toMatrix`, see mathlib4#3024
@[simp]
theorem toMatrix_apply [DecidableEq n] [Zero α] [One α] (f : m ≃. n) (i j) :
toMatrix f i j = if j ∈ f i then (1 : α) else 0 :=
rfl
#align pequiv.to_matrix_apply PEquiv.toMatrix_apply
theorem mul_matrix_apply [Fintype m] [DecidableEq m] [Semiring α] (f : l ≃. m) (M : Matrix m n α)
(i j) : (f.toMatrix * M :) i j = Option.casesOn (f i) 0 fun fi => M fi j := by
dsimp [toMatrix, Matrix.mul_apply]
cases' h : f i with fi
· simp [h]
· rw [Finset.sum_eq_single fi] <;> simp (config := { contextual := true }) [h, eq_comm]
#align pequiv.mul_matrix_apply PEquiv.mul_matrix_apply
theorem toMatrix_symm [DecidableEq m] [DecidableEq n] [Zero α] [One α] (f : m ≃. n) :
(f.symm.toMatrix : Matrix n m α) = f.toMatrixᵀ := by
ext
simp only [transpose, mem_iff_mem f, toMatrix_apply]
congr
#align pequiv.to_matrix_symm PEquiv.toMatrix_symm
@[simp]
theorem toMatrix_refl [DecidableEq n] [Zero α] [One α] :
((PEquiv.refl n).toMatrix : Matrix n n α) = 1 := by
ext
simp [toMatrix_apply, one_apply]
#align pequiv.to_matrix_refl PEquiv.toMatrix_refl
theorem matrix_mul_apply [Fintype m] [Semiring α] [DecidableEq n] (M : Matrix l m α) (f : m ≃. n)
(i j) : (M * f.toMatrix :) i j = Option.casesOn (f.symm j) 0 fun fj => M i fj := by
dsimp [toMatrix, Matrix.mul_apply]
cases' h : f.symm j with fj
· simp [h, ← f.eq_some_iff]
· rw [Finset.sum_eq_single fj]
· simp [h, ← f.eq_some_iff]
· rintro b - n
simp [h, ← f.eq_some_iff, n.symm]
· simp
#align pequiv.matrix_mul_apply PEquiv.matrix_mul_apply
theorem toPEquiv_mul_matrix [Fintype m] [DecidableEq m] [Semiring α] (f : m ≃ m)
(M : Matrix m n α) : f.toPEquiv.toMatrix * M = M.submatrix f id := by
ext i j
rw [mul_matrix_apply, Equiv.toPEquiv_apply, submatrix_apply, id]
#align pequiv.to_pequiv_mul_matrix PEquiv.toPEquiv_mul_matrix
theorem mul_toPEquiv_toMatrix {m n α : Type*} [Fintype n] [DecidableEq n] [Semiring α] (f : n ≃ n)
(M : Matrix m n α) : M * f.toPEquiv.toMatrix = M.submatrix id f.symm :=
Matrix.ext fun i j => by
rw [PEquiv.matrix_mul_apply, ← Equiv.toPEquiv_symm, Equiv.toPEquiv_apply,
Matrix.submatrix_apply, id]
#align pequiv.mul_to_pequiv_to_matrix PEquiv.mul_toPEquiv_toMatrix
theorem toMatrix_trans [Fintype m] [DecidableEq m] [DecidableEq n] [Semiring α] (f : l ≃. m)
(g : m ≃. n) : ((f.trans g).toMatrix : Matrix l n α) = f.toMatrix * g.toMatrix := by
ext i j
rw [mul_matrix_apply]
dsimp [toMatrix, PEquiv.trans]
cases f i <;> simp
#align pequiv.to_matrix_trans PEquiv.toMatrix_trans
@[simp]
theorem toMatrix_bot [DecidableEq n] [Zero α] [One α] :
((⊥ : PEquiv m n).toMatrix : Matrix m n α) = 0 :=
rfl
#align pequiv.to_matrix_bot PEquiv.toMatrix_bot
| Mathlib/Data/Matrix/PEquiv.lean | 123 | 139 | theorem toMatrix_injective [DecidableEq n] [MonoidWithZero α] [Nontrivial α] :
Function.Injective (@toMatrix m n α _ _ _) := by |
classical
intro f g
refine not_imp_not.1 ?_
simp only [Matrix.ext_iff.symm, toMatrix_apply, PEquiv.ext_iff, not_forall, exists_imp]
intro i hi
use i
cases' hf : f i with fi
· cases' hg : g i with gi
-- Porting note: was `cc`
· rw [hf, hg] at hi
exact (hi rfl).elim
· use gi
simp
· use fi
simp [hf.symm, Ne.symm hi]
|
/-
Copyright (c) 2021 Oliver Nash. All rights reserved.
Released under Apache 2.0 license as described in the file LICENSE.
Authors: Oliver Nash
-/
import Mathlib.Algebra.Lie.Subalgebra
import Mathlib.RingTheory.Noetherian
import Mathlib.RingTheory.Artinian
#align_import algebra.lie.submodule from "leanprover-community/mathlib"@"9822b65bfc4ac74537d77ae318d27df1df662471"
/-!
# Lie submodules of a Lie algebra
In this file we define Lie submodules and Lie ideals, we construct the lattice structure on Lie
submodules and we use it to define various important operations, notably the Lie span of a subset
of a Lie module.
## Main definitions
* `LieSubmodule`
* `LieSubmodule.wellFounded_of_noetherian`
* `LieSubmodule.lieSpan`
* `LieSubmodule.map`
* `LieSubmodule.comap`
* `LieIdeal`
* `LieIdeal.map`
* `LieIdeal.comap`
## Tags
lie algebra, lie submodule, lie ideal, lattice structure
-/
universe u v w w₁ w₂
section LieSubmodule
variable (R : Type u) (L : Type v) (M : Type w)
variable [CommRing R] [LieRing L] [LieAlgebra R L] [AddCommGroup M] [Module R M]
variable [LieRingModule L M] [LieModule R L M]
/-- A Lie submodule of a Lie module is a submodule that is closed under the Lie bracket.
This is a sufficient condition for the subset itself to form a Lie module. -/
structure LieSubmodule extends Submodule R M where
lie_mem : ∀ {x : L} {m : M}, m ∈ carrier → ⁅x, m⁆ ∈ carrier
#align lie_submodule LieSubmodule
attribute [nolint docBlame] LieSubmodule.toSubmodule
attribute [coe] LieSubmodule.toSubmodule
namespace LieSubmodule
variable {R L M}
variable (N N' : LieSubmodule R L M)
instance : SetLike (LieSubmodule R L M) M where
coe s := s.carrier
coe_injective' N O h := by cases N; cases O; congr; exact SetLike.coe_injective' h
instance : AddSubgroupClass (LieSubmodule R L M) M where
add_mem {N} _ _ := N.add_mem'
zero_mem N := N.zero_mem'
neg_mem {N} x hx := show -x ∈ N.toSubmodule from neg_mem hx
instance instSMulMemClass : SMulMemClass (LieSubmodule R L M) R M where
smul_mem {s} c _ h := s.smul_mem' c h
/-- The zero module is a Lie submodule of any Lie module. -/
instance : Zero (LieSubmodule R L M) :=
⟨{ (0 : Submodule R M) with
lie_mem := fun {x m} h ↦ by rw [(Submodule.mem_bot R).1 h]; apply lie_zero }⟩
instance : Inhabited (LieSubmodule R L M) :=
⟨0⟩
instance coeSubmodule : CoeOut (LieSubmodule R L M) (Submodule R M) :=
⟨toSubmodule⟩
#align lie_submodule.coe_submodule LieSubmodule.coeSubmodule
-- Syntactic tautology
#noalign lie_submodule.to_submodule_eq_coe
@[norm_cast]
theorem coe_toSubmodule : ((N : Submodule R M) : Set M) = N :=
rfl
#align lie_submodule.coe_to_submodule LieSubmodule.coe_toSubmodule
-- Porting note (#10618): `simp` can prove this after `mem_coeSubmodule` is added to the simp set,
-- but `dsimp` can't.
@[simp, nolint simpNF]
theorem mem_carrier {x : M} : x ∈ N.carrier ↔ x ∈ (N : Set M) :=
Iff.rfl
#align lie_submodule.mem_carrier LieSubmodule.mem_carrier
theorem mem_mk_iff (S : Set M) (h₁ h₂ h₃ h₄) {x : M} :
x ∈ (⟨⟨⟨⟨S, h₁⟩, h₂⟩, h₃⟩, h₄⟩ : LieSubmodule R L M) ↔ x ∈ S :=
Iff.rfl
#align lie_submodule.mem_mk_iff LieSubmodule.mem_mk_iff
@[simp]
theorem mem_mk_iff' (p : Submodule R M) (h) {x : M} :
x ∈ (⟨p, h⟩ : LieSubmodule R L M) ↔ x ∈ p :=
Iff.rfl
@[simp]
theorem mem_coeSubmodule {x : M} : x ∈ (N : Submodule R M) ↔ x ∈ N :=
Iff.rfl
#align lie_submodule.mem_coe_submodule LieSubmodule.mem_coeSubmodule
theorem mem_coe {x : M} : x ∈ (N : Set M) ↔ x ∈ N :=
Iff.rfl
#align lie_submodule.mem_coe LieSubmodule.mem_coe
@[simp]
protected theorem zero_mem : (0 : M) ∈ N :=
zero_mem N
#align lie_submodule.zero_mem LieSubmodule.zero_mem
-- Porting note (#10618): @[simp] can prove this
theorem mk_eq_zero {x} (h : x ∈ N) : (⟨x, h⟩ : N) = 0 ↔ x = 0 :=
Subtype.ext_iff_val
#align lie_submodule.mk_eq_zero LieSubmodule.mk_eq_zero
@[simp]
theorem coe_toSet_mk (S : Set M) (h₁ h₂ h₃ h₄) :
((⟨⟨⟨⟨S, h₁⟩, h₂⟩, h₃⟩, h₄⟩ : LieSubmodule R L M) : Set M) = S :=
rfl
#align lie_submodule.coe_to_set_mk LieSubmodule.coe_toSet_mk
| Mathlib/Algebra/Lie/Submodule.lean | 132 | 133 | theorem coe_toSubmodule_mk (p : Submodule R M) (h) :
(({ p with lie_mem := h } : LieSubmodule R L M) : Submodule R M) = p := by | cases p; rfl
|
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