Context stringlengths 57 6.04k | file_name stringlengths 21 79 | start int64 14 1.49k | end int64 18 1.5k | theorem stringlengths 25 1.55k | proof stringlengths 5 7.36k | rank int64 0 2.4k |
|---|---|---|---|---|---|---|
import Mathlib.Data.Nat.Multiplicity
import Mathlib.Data.ZMod.Algebra
import Mathlib.RingTheory.WittVector.Basic
import Mathlib.RingTheory.WittVector.IsPoly
import Mathlib.FieldTheory.Perfect
#align_import ring_theory.witt_vector.frobenius from "leanprover-community/mathlib"@"0723536a0522d24fc2f159a096fb3304bef77472"
namespace WittVector
variable {p : ℕ} {R S : Type*} [hp : Fact p.Prime] [CommRing R] [CommRing S]
local notation "𝕎" => WittVector p -- type as `\bbW`
noncomputable section
open MvPolynomial Finset
variable (p)
def frobeniusPolyRat (n : ℕ) : MvPolynomial ℕ ℚ :=
bind₁ (wittPolynomial p ℚ ∘ fun n => n + 1) (xInTermsOfW p ℚ n)
#align witt_vector.frobenius_poly_rat WittVector.frobeniusPolyRat
| Mathlib/RingTheory/WittVector/Frobenius.lean | 71 | 74 | theorem bind₁_frobeniusPolyRat_wittPolynomial (n : ℕ) :
bind₁ (frobeniusPolyRat p) (wittPolynomial p ℚ n) = wittPolynomial p ℚ (n + 1) := by |
delta frobeniusPolyRat
rw [← bind₁_bind₁, bind₁_xInTermsOfW_wittPolynomial, bind₁_X_right, Function.comp_apply]
| 2,002 |
import Mathlib.Data.Nat.Multiplicity
import Mathlib.Data.ZMod.Algebra
import Mathlib.RingTheory.WittVector.Basic
import Mathlib.RingTheory.WittVector.IsPoly
import Mathlib.FieldTheory.Perfect
#align_import ring_theory.witt_vector.frobenius from "leanprover-community/mathlib"@"0723536a0522d24fc2f159a096fb3304bef77472"
namespace WittVector
variable {p : ℕ} {R S : Type*} [hp : Fact p.Prime] [CommRing R] [CommRing S]
local notation "𝕎" => WittVector p -- type as `\bbW`
noncomputable section
open MvPolynomial Finset
variable (p)
def frobeniusPolyRat (n : ℕ) : MvPolynomial ℕ ℚ :=
bind₁ (wittPolynomial p ℚ ∘ fun n => n + 1) (xInTermsOfW p ℚ n)
#align witt_vector.frobenius_poly_rat WittVector.frobeniusPolyRat
theorem bind₁_frobeniusPolyRat_wittPolynomial (n : ℕ) :
bind₁ (frobeniusPolyRat p) (wittPolynomial p ℚ n) = wittPolynomial p ℚ (n + 1) := by
delta frobeniusPolyRat
rw [← bind₁_bind₁, bind₁_xInTermsOfW_wittPolynomial, bind₁_X_right, Function.comp_apply]
#align witt_vector.bind₁_frobenius_poly_rat_witt_polynomial WittVector.bind₁_frobeniusPolyRat_wittPolynomial
private def pnat_multiplicity (n : ℕ+) : ℕ :=
(multiplicity p n).get <| multiplicity.finite_nat_iff.mpr <| ⟨ne_of_gt hp.1.one_lt, n.2⟩
local notation "v" => pnat_multiplicity
noncomputable def frobeniusPolyAux : ℕ → MvPolynomial ℕ ℤ
| n => X (n + 1) - ∑ i : Fin n, have _ := i.is_lt
∑ j ∈ range (p ^ (n - i)),
(((X (i : ℕ) ^ p) ^ (p ^ (n - (i : ℕ)) - (j + 1)) : MvPolynomial ℕ ℤ) *
(frobeniusPolyAux i) ^ (j + 1)) *
C (((p ^ (n - i)).choose (j + 1) / (p ^ (n - i - v p ⟨j + 1, Nat.succ_pos j⟩))
* ↑p ^ (j - v p ⟨j + 1, Nat.succ_pos j⟩) : ℕ) : ℤ)
#align witt_vector.frobenius_poly_aux WittVector.frobeniusPolyAux
| Mathlib/RingTheory/WittVector/Frobenius.lean | 97 | 104 | theorem frobeniusPolyAux_eq (n : ℕ) :
frobeniusPolyAux p n =
X (n + 1) - ∑ i ∈ range n,
∑ j ∈ range (p ^ (n - i)),
(X i ^ p) ^ (p ^ (n - i) - (j + 1)) * frobeniusPolyAux p i ^ (j + 1) *
C ↑((p ^ (n - i)).choose (j + 1) / p ^ (n - i - v p ⟨j + 1, Nat.succ_pos j⟩) *
↑p ^ (j - v p ⟨j + 1, Nat.succ_pos j⟩) : ℕ) := by |
rw [frobeniusPolyAux, ← Fin.sum_univ_eq_sum_range]
| 2,002 |
import Mathlib.Data.Nat.Multiplicity
import Mathlib.Data.ZMod.Algebra
import Mathlib.RingTheory.WittVector.Basic
import Mathlib.RingTheory.WittVector.IsPoly
import Mathlib.FieldTheory.Perfect
#align_import ring_theory.witt_vector.frobenius from "leanprover-community/mathlib"@"0723536a0522d24fc2f159a096fb3304bef77472"
namespace WittVector
variable {p : ℕ} {R S : Type*} [hp : Fact p.Prime] [CommRing R] [CommRing S]
local notation "𝕎" => WittVector p -- type as `\bbW`
noncomputable section
open MvPolynomial Finset
variable (p)
def frobeniusPolyRat (n : ℕ) : MvPolynomial ℕ ℚ :=
bind₁ (wittPolynomial p ℚ ∘ fun n => n + 1) (xInTermsOfW p ℚ n)
#align witt_vector.frobenius_poly_rat WittVector.frobeniusPolyRat
theorem bind₁_frobeniusPolyRat_wittPolynomial (n : ℕ) :
bind₁ (frobeniusPolyRat p) (wittPolynomial p ℚ n) = wittPolynomial p ℚ (n + 1) := by
delta frobeniusPolyRat
rw [← bind₁_bind₁, bind₁_xInTermsOfW_wittPolynomial, bind₁_X_right, Function.comp_apply]
#align witt_vector.bind₁_frobenius_poly_rat_witt_polynomial WittVector.bind₁_frobeniusPolyRat_wittPolynomial
private def pnat_multiplicity (n : ℕ+) : ℕ :=
(multiplicity p n).get <| multiplicity.finite_nat_iff.mpr <| ⟨ne_of_gt hp.1.one_lt, n.2⟩
local notation "v" => pnat_multiplicity
noncomputable def frobeniusPolyAux : ℕ → MvPolynomial ℕ ℤ
| n => X (n + 1) - ∑ i : Fin n, have _ := i.is_lt
∑ j ∈ range (p ^ (n - i)),
(((X (i : ℕ) ^ p) ^ (p ^ (n - (i : ℕ)) - (j + 1)) : MvPolynomial ℕ ℤ) *
(frobeniusPolyAux i) ^ (j + 1)) *
C (((p ^ (n - i)).choose (j + 1) / (p ^ (n - i - v p ⟨j + 1, Nat.succ_pos j⟩))
* ↑p ^ (j - v p ⟨j + 1, Nat.succ_pos j⟩) : ℕ) : ℤ)
#align witt_vector.frobenius_poly_aux WittVector.frobeniusPolyAux
theorem frobeniusPolyAux_eq (n : ℕ) :
frobeniusPolyAux p n =
X (n + 1) - ∑ i ∈ range n,
∑ j ∈ range (p ^ (n - i)),
(X i ^ p) ^ (p ^ (n - i) - (j + 1)) * frobeniusPolyAux p i ^ (j + 1) *
C ↑((p ^ (n - i)).choose (j + 1) / p ^ (n - i - v p ⟨j + 1, Nat.succ_pos j⟩) *
↑p ^ (j - v p ⟨j + 1, Nat.succ_pos j⟩) : ℕ) := by
rw [frobeniusPolyAux, ← Fin.sum_univ_eq_sum_range]
#align witt_vector.frobenius_poly_aux_eq WittVector.frobeniusPolyAux_eq
def frobeniusPoly (n : ℕ) : MvPolynomial ℕ ℤ :=
X n ^ p + C (p : ℤ) * frobeniusPolyAux p n
#align witt_vector.frobenius_poly WittVector.frobeniusPoly
| Mathlib/RingTheory/WittVector/Frobenius.lean | 123 | 127 | theorem map_frobeniusPoly.key₁ (n j : ℕ) (hj : j < p ^ n) :
p ^ (n - v p ⟨j + 1, j.succ_pos⟩) ∣ (p ^ n).choose (j + 1) := by |
apply multiplicity.pow_dvd_of_le_multiplicity
rw [hp.out.multiplicity_choose_prime_pow hj j.succ_ne_zero]
rfl
| 2,002 |
import Mathlib.Data.Nat.Multiplicity
import Mathlib.Data.ZMod.Algebra
import Mathlib.RingTheory.WittVector.Basic
import Mathlib.RingTheory.WittVector.IsPoly
import Mathlib.FieldTheory.Perfect
#align_import ring_theory.witt_vector.frobenius from "leanprover-community/mathlib"@"0723536a0522d24fc2f159a096fb3304bef77472"
namespace WittVector
variable {p : ℕ} {R S : Type*} [hp : Fact p.Prime] [CommRing R] [CommRing S]
local notation "𝕎" => WittVector p -- type as `\bbW`
noncomputable section
open MvPolynomial Finset
variable (p)
def frobeniusPolyRat (n : ℕ) : MvPolynomial ℕ ℚ :=
bind₁ (wittPolynomial p ℚ ∘ fun n => n + 1) (xInTermsOfW p ℚ n)
#align witt_vector.frobenius_poly_rat WittVector.frobeniusPolyRat
theorem bind₁_frobeniusPolyRat_wittPolynomial (n : ℕ) :
bind₁ (frobeniusPolyRat p) (wittPolynomial p ℚ n) = wittPolynomial p ℚ (n + 1) := by
delta frobeniusPolyRat
rw [← bind₁_bind₁, bind₁_xInTermsOfW_wittPolynomial, bind₁_X_right, Function.comp_apply]
#align witt_vector.bind₁_frobenius_poly_rat_witt_polynomial WittVector.bind₁_frobeniusPolyRat_wittPolynomial
private def pnat_multiplicity (n : ℕ+) : ℕ :=
(multiplicity p n).get <| multiplicity.finite_nat_iff.mpr <| ⟨ne_of_gt hp.1.one_lt, n.2⟩
local notation "v" => pnat_multiplicity
noncomputable def frobeniusPolyAux : ℕ → MvPolynomial ℕ ℤ
| n => X (n + 1) - ∑ i : Fin n, have _ := i.is_lt
∑ j ∈ range (p ^ (n - i)),
(((X (i : ℕ) ^ p) ^ (p ^ (n - (i : ℕ)) - (j + 1)) : MvPolynomial ℕ ℤ) *
(frobeniusPolyAux i) ^ (j + 1)) *
C (((p ^ (n - i)).choose (j + 1) / (p ^ (n - i - v p ⟨j + 1, Nat.succ_pos j⟩))
* ↑p ^ (j - v p ⟨j + 1, Nat.succ_pos j⟩) : ℕ) : ℤ)
#align witt_vector.frobenius_poly_aux WittVector.frobeniusPolyAux
theorem frobeniusPolyAux_eq (n : ℕ) :
frobeniusPolyAux p n =
X (n + 1) - ∑ i ∈ range n,
∑ j ∈ range (p ^ (n - i)),
(X i ^ p) ^ (p ^ (n - i) - (j + 1)) * frobeniusPolyAux p i ^ (j + 1) *
C ↑((p ^ (n - i)).choose (j + 1) / p ^ (n - i - v p ⟨j + 1, Nat.succ_pos j⟩) *
↑p ^ (j - v p ⟨j + 1, Nat.succ_pos j⟩) : ℕ) := by
rw [frobeniusPolyAux, ← Fin.sum_univ_eq_sum_range]
#align witt_vector.frobenius_poly_aux_eq WittVector.frobeniusPolyAux_eq
def frobeniusPoly (n : ℕ) : MvPolynomial ℕ ℤ :=
X n ^ p + C (p : ℤ) * frobeniusPolyAux p n
#align witt_vector.frobenius_poly WittVector.frobeniusPoly
theorem map_frobeniusPoly.key₁ (n j : ℕ) (hj : j < p ^ n) :
p ^ (n - v p ⟨j + 1, j.succ_pos⟩) ∣ (p ^ n).choose (j + 1) := by
apply multiplicity.pow_dvd_of_le_multiplicity
rw [hp.out.multiplicity_choose_prime_pow hj j.succ_ne_zero]
rfl
#align witt_vector.map_frobenius_poly.key₁ WittVector.map_frobeniusPoly.key₁
| Mathlib/RingTheory/WittVector/Frobenius.lean | 131 | 140 | theorem map_frobeniusPoly.key₂ {n i j : ℕ} (hi : i ≤ n) (hj : j < p ^ (n - i)) :
j - v p ⟨j + 1, j.succ_pos⟩ + n = i + j + (n - i - v p ⟨j + 1, j.succ_pos⟩) := by |
generalize h : v p ⟨j + 1, j.succ_pos⟩ = m
rsuffices ⟨h₁, h₂⟩ : m ≤ n - i ∧ m ≤ j
· rw [tsub_add_eq_add_tsub h₂, add_comm i j, add_tsub_assoc_of_le (h₁.trans (Nat.sub_le n i)),
add_assoc, tsub_right_comm, add_comm i,
tsub_add_cancel_of_le (le_tsub_of_add_le_right ((le_tsub_iff_left hi).mp h₁))]
have hle : p ^ m ≤ j + 1 := h ▸ Nat.le_of_dvd j.succ_pos (multiplicity.pow_multiplicity_dvd _)
exact ⟨(pow_le_pow_iff_right hp.1.one_lt).1 (hle.trans hj),
Nat.le_of_lt_succ ((Nat.lt_pow_self hp.1.one_lt m).trans_le hle)⟩
| 2,002 |
import Mathlib.Data.Nat.Multiplicity
import Mathlib.Data.ZMod.Algebra
import Mathlib.RingTheory.WittVector.Basic
import Mathlib.RingTheory.WittVector.IsPoly
import Mathlib.FieldTheory.Perfect
#align_import ring_theory.witt_vector.frobenius from "leanprover-community/mathlib"@"0723536a0522d24fc2f159a096fb3304bef77472"
namespace WittVector
variable {p : ℕ} {R S : Type*} [hp : Fact p.Prime] [CommRing R] [CommRing S]
local notation "𝕎" => WittVector p -- type as `\bbW`
noncomputable section
open MvPolynomial Finset
variable (p)
def frobeniusPolyRat (n : ℕ) : MvPolynomial ℕ ℚ :=
bind₁ (wittPolynomial p ℚ ∘ fun n => n + 1) (xInTermsOfW p ℚ n)
#align witt_vector.frobenius_poly_rat WittVector.frobeniusPolyRat
theorem bind₁_frobeniusPolyRat_wittPolynomial (n : ℕ) :
bind₁ (frobeniusPolyRat p) (wittPolynomial p ℚ n) = wittPolynomial p ℚ (n + 1) := by
delta frobeniusPolyRat
rw [← bind₁_bind₁, bind₁_xInTermsOfW_wittPolynomial, bind₁_X_right, Function.comp_apply]
#align witt_vector.bind₁_frobenius_poly_rat_witt_polynomial WittVector.bind₁_frobeniusPolyRat_wittPolynomial
private def pnat_multiplicity (n : ℕ+) : ℕ :=
(multiplicity p n).get <| multiplicity.finite_nat_iff.mpr <| ⟨ne_of_gt hp.1.one_lt, n.2⟩
local notation "v" => pnat_multiplicity
noncomputable def frobeniusPolyAux : ℕ → MvPolynomial ℕ ℤ
| n => X (n + 1) - ∑ i : Fin n, have _ := i.is_lt
∑ j ∈ range (p ^ (n - i)),
(((X (i : ℕ) ^ p) ^ (p ^ (n - (i : ℕ)) - (j + 1)) : MvPolynomial ℕ ℤ) *
(frobeniusPolyAux i) ^ (j + 1)) *
C (((p ^ (n - i)).choose (j + 1) / (p ^ (n - i - v p ⟨j + 1, Nat.succ_pos j⟩))
* ↑p ^ (j - v p ⟨j + 1, Nat.succ_pos j⟩) : ℕ) : ℤ)
#align witt_vector.frobenius_poly_aux WittVector.frobeniusPolyAux
theorem frobeniusPolyAux_eq (n : ℕ) :
frobeniusPolyAux p n =
X (n + 1) - ∑ i ∈ range n,
∑ j ∈ range (p ^ (n - i)),
(X i ^ p) ^ (p ^ (n - i) - (j + 1)) * frobeniusPolyAux p i ^ (j + 1) *
C ↑((p ^ (n - i)).choose (j + 1) / p ^ (n - i - v p ⟨j + 1, Nat.succ_pos j⟩) *
↑p ^ (j - v p ⟨j + 1, Nat.succ_pos j⟩) : ℕ) := by
rw [frobeniusPolyAux, ← Fin.sum_univ_eq_sum_range]
#align witt_vector.frobenius_poly_aux_eq WittVector.frobeniusPolyAux_eq
def frobeniusPoly (n : ℕ) : MvPolynomial ℕ ℤ :=
X n ^ p + C (p : ℤ) * frobeniusPolyAux p n
#align witt_vector.frobenius_poly WittVector.frobeniusPoly
theorem map_frobeniusPoly.key₁ (n j : ℕ) (hj : j < p ^ n) :
p ^ (n - v p ⟨j + 1, j.succ_pos⟩) ∣ (p ^ n).choose (j + 1) := by
apply multiplicity.pow_dvd_of_le_multiplicity
rw [hp.out.multiplicity_choose_prime_pow hj j.succ_ne_zero]
rfl
#align witt_vector.map_frobenius_poly.key₁ WittVector.map_frobeniusPoly.key₁
theorem map_frobeniusPoly.key₂ {n i j : ℕ} (hi : i ≤ n) (hj : j < p ^ (n - i)) :
j - v p ⟨j + 1, j.succ_pos⟩ + n = i + j + (n - i - v p ⟨j + 1, j.succ_pos⟩) := by
generalize h : v p ⟨j + 1, j.succ_pos⟩ = m
rsuffices ⟨h₁, h₂⟩ : m ≤ n - i ∧ m ≤ j
· rw [tsub_add_eq_add_tsub h₂, add_comm i j, add_tsub_assoc_of_le (h₁.trans (Nat.sub_le n i)),
add_assoc, tsub_right_comm, add_comm i,
tsub_add_cancel_of_le (le_tsub_of_add_le_right ((le_tsub_iff_left hi).mp h₁))]
have hle : p ^ m ≤ j + 1 := h ▸ Nat.le_of_dvd j.succ_pos (multiplicity.pow_multiplicity_dvd _)
exact ⟨(pow_le_pow_iff_right hp.1.one_lt).1 (hle.trans hj),
Nat.le_of_lt_succ ((Nat.lt_pow_self hp.1.one_lt m).trans_le hle)⟩
#align witt_vector.map_frobenius_poly.key₂ WittVector.map_frobeniusPoly.key₂
| Mathlib/RingTheory/WittVector/Frobenius.lean | 143 | 193 | theorem map_frobeniusPoly (n : ℕ) :
MvPolynomial.map (Int.castRingHom ℚ) (frobeniusPoly p n) = frobeniusPolyRat p n := by |
rw [frobeniusPoly, RingHom.map_add, RingHom.map_mul, RingHom.map_pow, map_C, map_X, eq_intCast,
Int.cast_natCast, frobeniusPolyRat]
refine Nat.strong_induction_on n ?_; clear n
intro n IH
rw [xInTermsOfW_eq]
simp only [AlgHom.map_sum, AlgHom.map_sub, AlgHom.map_mul, AlgHom.map_pow, bind₁_C_right]
have h1 : (p : ℚ) ^ n * ⅟ (p : ℚ) ^ n = 1 := by rw [← mul_pow, mul_invOf_self, one_pow]
rw [bind₁_X_right, Function.comp_apply, wittPolynomial_eq_sum_C_mul_X_pow, sum_range_succ,
sum_range_succ, tsub_self, add_tsub_cancel_left, pow_zero, pow_one, pow_one, sub_mul, add_mul,
add_mul, mul_right_comm, mul_right_comm (C ((p : ℚ) ^ (n + 1))), ← C_mul, ← C_mul, pow_succ',
mul_assoc (p : ℚ) ((p : ℚ) ^ n), h1, mul_one, C_1, one_mul, add_comm _ (X n ^ p), add_assoc,
← add_sub, add_right_inj, frobeniusPolyAux_eq, RingHom.map_sub, map_X, mul_sub, sub_eq_add_neg,
add_comm _ (C (p : ℚ) * X (n + 1)), ← add_sub,
add_right_inj, neg_eq_iff_eq_neg, neg_sub, eq_comm]
simp only [map_sum, mul_sum, sum_mul, ← sum_sub_distrib]
apply sum_congr rfl
intro i hi
rw [mem_range] at hi
rw [← IH i hi]
clear IH
rw [add_comm (X i ^ p), add_pow, sum_range_succ', pow_zero, tsub_zero, Nat.choose_zero_right,
one_mul, Nat.cast_one, mul_one, mul_add, add_mul, Nat.succ_sub (le_of_lt hi),
Nat.succ_eq_add_one (n - i), pow_succ', pow_mul, add_sub_cancel_right, mul_sum, sum_mul]
apply sum_congr rfl
intro j hj
rw [mem_range] at hj
rw [RingHom.map_mul, RingHom.map_mul, RingHom.map_pow, RingHom.map_pow, RingHom.map_pow,
RingHom.map_pow, RingHom.map_pow, map_C, map_X, mul_pow]
rw [mul_comm (C (p : ℚ) ^ i), mul_comm _ ((X i ^ p) ^ _), mul_comm (C (p : ℚ) ^ (j + 1)),
mul_comm (C (p : ℚ))]
simp only [mul_assoc]
apply congr_arg
apply congr_arg
rw [← C_eq_coe_nat]
simp only [← RingHom.map_pow, ← C_mul]
rw [C_inj]
simp only [invOf_eq_inv, eq_intCast, inv_pow, Int.cast_natCast, Nat.cast_mul, Int.cast_mul]
rw [Rat.natCast_div _ _ (map_frobeniusPoly.key₁ p (n - i) j hj)]
simp only [Nat.cast_pow, pow_add, pow_one]
suffices
(((p ^ (n - i)).choose (j + 1): ℚ) * (p : ℚ) ^ (j - v p ⟨j + 1, j.succ_pos⟩) * ↑p * (p ^ n : ℚ))
= (p : ℚ) ^ j * p * ↑((p ^ (n - i)).choose (j + 1) * p ^ i) *
(p : ℚ) ^ (n - i - v p ⟨j + 1, j.succ_pos⟩) by
have aux : ∀ k : ℕ, (p : ℚ)^ k ≠ 0 := by
intro; apply pow_ne_zero; exact mod_cast hp.1.ne_zero
simpa [aux, -one_div, -pow_eq_zero_iff', field_simps] using this.symm
rw [mul_comm _ (p : ℚ), mul_assoc, mul_assoc, ← pow_add,
map_frobeniusPoly.key₂ p hi.le hj, Nat.cast_mul, Nat.cast_pow]
ring
| 2,002 |
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"
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.
| Mathlib/RingTheory/WittVector/Identities.lean | 42 | 47 | 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]
| 2,003 |
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"
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.
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
| Mathlib/RingTheory/WittVector/Identities.lean | 51 | 52 | theorem verschiebung_zmod (x : 𝕎 (ZMod p)) : verschiebung x = x * p := by |
rw [← frobenius_verschiebung, frobenius_zmodp]
| 2,003 |
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"
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.
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
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]
| 2,003 |
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"
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.
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
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)
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]
#align witt_vector.coeff_p_pow WittVector.coeff_p_pow
| Mathlib/RingTheory/WittVector/Identities.lean | 64 | 71 | theorem coeff_p_pow_eq_zero [CharP R p] {i j : ℕ} (hj : j ≠ i) : ((p : 𝕎 R) ^ i).coeff j = 0 := by |
induction' i with i hi generalizing j
· rw [pow_zero, one_coeff_eq_of_pos]
exact Nat.pos_of_ne_zero hj
· rw [pow_succ, ← frobenius_verschiebung, coeff_frobenius_charP]
cases j
· rw [verschiebung_coeff_zero, zero_pow hp.out.ne_zero]
· rw [verschiebung_coeff_succ, hi (ne_of_apply_ne _ hj), zero_pow hp.out.ne_zero]
| 2,003 |
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"
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.
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
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)
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]
#align witt_vector.coeff_p_pow WittVector.coeff_p_pow
theorem coeff_p_pow_eq_zero [CharP R p] {i j : ℕ} (hj : j ≠ i) : ((p : 𝕎 R) ^ i).coeff j = 0 := by
induction' i with i hi generalizing j
· rw [pow_zero, one_coeff_eq_of_pos]
exact Nat.pos_of_ne_zero hj
· rw [pow_succ, ← frobenius_verschiebung, coeff_frobenius_charP]
cases j
· rw [verschiebung_coeff_zero, zero_pow hp.out.ne_zero]
· rw [verschiebung_coeff_succ, hi (ne_of_apply_ne _ hj), zero_pow hp.out.ne_zero]
#align witt_vector.coeff_p_pow_eq_zero WittVector.coeff_p_pow_eq_zero
| Mathlib/RingTheory/WittVector/Identities.lean | 74 | 77 | theorem coeff_p [CharP R p] (i : ℕ) : (p : 𝕎 R).coeff i = if i = 1 then 1 else 0 := by |
split_ifs with hi
· simpa only [hi, pow_one] using coeff_p_pow p R 1
· simpa only [pow_one] using coeff_p_pow_eq_zero p R hi
| 2,003 |
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"
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.
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
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)
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]
#align witt_vector.coeff_p_pow WittVector.coeff_p_pow
theorem coeff_p_pow_eq_zero [CharP R p] {i j : ℕ} (hj : j ≠ i) : ((p : 𝕎 R) ^ i).coeff j = 0 := by
induction' i with i hi generalizing j
· rw [pow_zero, one_coeff_eq_of_pos]
exact Nat.pos_of_ne_zero hj
· rw [pow_succ, ← frobenius_verschiebung, coeff_frobenius_charP]
cases j
· rw [verschiebung_coeff_zero, zero_pow hp.out.ne_zero]
· rw [verschiebung_coeff_succ, hi (ne_of_apply_ne _ hj), zero_pow hp.out.ne_zero]
#align witt_vector.coeff_p_pow_eq_zero WittVector.coeff_p_pow_eq_zero
theorem coeff_p [CharP R p] (i : ℕ) : (p : 𝕎 R).coeff i = if i = 1 then 1 else 0 := by
split_ifs with hi
· simpa only [hi, pow_one] using coeff_p_pow p R 1
· simpa only [pow_one] using coeff_p_pow_eq_zero p R hi
#align witt_vector.coeff_p WittVector.coeff_p
@[simp]
| Mathlib/RingTheory/WittVector/Identities.lean | 81 | 83 | theorem coeff_p_zero [CharP R p] : (p : 𝕎 R).coeff 0 = 0 := by |
rw [coeff_p, if_neg]
exact zero_ne_one
| 2,003 |
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"
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.
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
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)
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]
#align witt_vector.coeff_p_pow WittVector.coeff_p_pow
theorem coeff_p_pow_eq_zero [CharP R p] {i j : ℕ} (hj : j ≠ i) : ((p : 𝕎 R) ^ i).coeff j = 0 := by
induction' i with i hi generalizing j
· rw [pow_zero, one_coeff_eq_of_pos]
exact Nat.pos_of_ne_zero hj
· rw [pow_succ, ← frobenius_verschiebung, coeff_frobenius_charP]
cases j
· rw [verschiebung_coeff_zero, zero_pow hp.out.ne_zero]
· rw [verschiebung_coeff_succ, hi (ne_of_apply_ne _ hj), zero_pow hp.out.ne_zero]
#align witt_vector.coeff_p_pow_eq_zero WittVector.coeff_p_pow_eq_zero
theorem coeff_p [CharP R p] (i : ℕ) : (p : 𝕎 R).coeff i = if i = 1 then 1 else 0 := by
split_ifs with hi
· simpa only [hi, pow_one] using coeff_p_pow p R 1
· simpa only [pow_one] using coeff_p_pow_eq_zero p R hi
#align witt_vector.coeff_p WittVector.coeff_p
@[simp]
theorem coeff_p_zero [CharP R p] : (p : 𝕎 R).coeff 0 = 0 := by
rw [coeff_p, if_neg]
exact zero_ne_one
#align witt_vector.coeff_p_zero WittVector.coeff_p_zero
@[simp]
| Mathlib/RingTheory/WittVector/Identities.lean | 87 | 87 | theorem coeff_p_one [CharP R p] : (p : 𝕎 R).coeff 1 = 1 := by | rw [coeff_p, if_pos rfl]
| 2,003 |
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"
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.
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
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)
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]
#align witt_vector.coeff_p_pow WittVector.coeff_p_pow
theorem coeff_p_pow_eq_zero [CharP R p] {i j : ℕ} (hj : j ≠ i) : ((p : 𝕎 R) ^ i).coeff j = 0 := by
induction' i with i hi generalizing j
· rw [pow_zero, one_coeff_eq_of_pos]
exact Nat.pos_of_ne_zero hj
· rw [pow_succ, ← frobenius_verschiebung, coeff_frobenius_charP]
cases j
· rw [verschiebung_coeff_zero, zero_pow hp.out.ne_zero]
· rw [verschiebung_coeff_succ, hi (ne_of_apply_ne _ hj), zero_pow hp.out.ne_zero]
#align witt_vector.coeff_p_pow_eq_zero WittVector.coeff_p_pow_eq_zero
theorem coeff_p [CharP R p] (i : ℕ) : (p : 𝕎 R).coeff i = if i = 1 then 1 else 0 := by
split_ifs with hi
· simpa only [hi, pow_one] using coeff_p_pow p R 1
· simpa only [pow_one] using coeff_p_pow_eq_zero p R hi
#align witt_vector.coeff_p WittVector.coeff_p
@[simp]
theorem coeff_p_zero [CharP R p] : (p : 𝕎 R).coeff 0 = 0 := by
rw [coeff_p, if_neg]
exact zero_ne_one
#align witt_vector.coeff_p_zero WittVector.coeff_p_zero
@[simp]
theorem coeff_p_one [CharP R p] : (p : 𝕎 R).coeff 1 = 1 := by rw [coeff_p, if_pos rfl]
#align witt_vector.coeff_p_one WittVector.coeff_p_one
| Mathlib/RingTheory/WittVector/Identities.lean | 90 | 92 | theorem p_nonzero [Nontrivial R] [CharP R p] : (p : 𝕎 R) ≠ 0 := by |
intro h
simpa only [h, zero_coeff, zero_ne_one] using coeff_p_one p R
| 2,003 |
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"
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.
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
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)
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]
#align witt_vector.coeff_p_pow WittVector.coeff_p_pow
theorem coeff_p_pow_eq_zero [CharP R p] {i j : ℕ} (hj : j ≠ i) : ((p : 𝕎 R) ^ i).coeff j = 0 := by
induction' i with i hi generalizing j
· rw [pow_zero, one_coeff_eq_of_pos]
exact Nat.pos_of_ne_zero hj
· rw [pow_succ, ← frobenius_verschiebung, coeff_frobenius_charP]
cases j
· rw [verschiebung_coeff_zero, zero_pow hp.out.ne_zero]
· rw [verschiebung_coeff_succ, hi (ne_of_apply_ne _ hj), zero_pow hp.out.ne_zero]
#align witt_vector.coeff_p_pow_eq_zero WittVector.coeff_p_pow_eq_zero
theorem coeff_p [CharP R p] (i : ℕ) : (p : 𝕎 R).coeff i = if i = 1 then 1 else 0 := by
split_ifs with hi
· simpa only [hi, pow_one] using coeff_p_pow p R 1
· simpa only [pow_one] using coeff_p_pow_eq_zero p R hi
#align witt_vector.coeff_p WittVector.coeff_p
@[simp]
theorem coeff_p_zero [CharP R p] : (p : 𝕎 R).coeff 0 = 0 := by
rw [coeff_p, if_neg]
exact zero_ne_one
#align witt_vector.coeff_p_zero WittVector.coeff_p_zero
@[simp]
theorem coeff_p_one [CharP R p] : (p : 𝕎 R).coeff 1 = 1 := by rw [coeff_p, if_pos rfl]
#align witt_vector.coeff_p_one WittVector.coeff_p_one
theorem p_nonzero [Nontrivial R] [CharP R p] : (p : 𝕎 R) ≠ 0 := by
intro h
simpa only [h, zero_coeff, zero_ne_one] using coeff_p_one p R
#align witt_vector.p_nonzero WittVector.p_nonzero
| Mathlib/RingTheory/WittVector/Identities.lean | 95 | 96 | theorem FractionRing.p_nonzero [Nontrivial R] [CharP R p] : (p : FractionRing (𝕎 R)) ≠ 0 := by |
simpa using (IsFractionRing.injective (𝕎 R) (FractionRing (𝕎 R))).ne (WittVector.p_nonzero _ _)
| 2,003 |
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"
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.
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
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)
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]
#align witt_vector.coeff_p_pow WittVector.coeff_p_pow
theorem coeff_p_pow_eq_zero [CharP R p] {i j : ℕ} (hj : j ≠ i) : ((p : 𝕎 R) ^ i).coeff j = 0 := by
induction' i with i hi generalizing j
· rw [pow_zero, one_coeff_eq_of_pos]
exact Nat.pos_of_ne_zero hj
· rw [pow_succ, ← frobenius_verschiebung, coeff_frobenius_charP]
cases j
· rw [verschiebung_coeff_zero, zero_pow hp.out.ne_zero]
· rw [verschiebung_coeff_succ, hi (ne_of_apply_ne _ hj), zero_pow hp.out.ne_zero]
#align witt_vector.coeff_p_pow_eq_zero WittVector.coeff_p_pow_eq_zero
theorem coeff_p [CharP R p] (i : ℕ) : (p : 𝕎 R).coeff i = if i = 1 then 1 else 0 := by
split_ifs with hi
· simpa only [hi, pow_one] using coeff_p_pow p R 1
· simpa only [pow_one] using coeff_p_pow_eq_zero p R hi
#align witt_vector.coeff_p WittVector.coeff_p
@[simp]
theorem coeff_p_zero [CharP R p] : (p : 𝕎 R).coeff 0 = 0 := by
rw [coeff_p, if_neg]
exact zero_ne_one
#align witt_vector.coeff_p_zero WittVector.coeff_p_zero
@[simp]
theorem coeff_p_one [CharP R p] : (p : 𝕎 R).coeff 1 = 1 := by rw [coeff_p, if_pos rfl]
#align witt_vector.coeff_p_one WittVector.coeff_p_one
theorem p_nonzero [Nontrivial R] [CharP R p] : (p : 𝕎 R) ≠ 0 := by
intro h
simpa only [h, zero_coeff, zero_ne_one] using coeff_p_one p R
#align witt_vector.p_nonzero WittVector.p_nonzero
theorem FractionRing.p_nonzero [Nontrivial R] [CharP R p] : (p : FractionRing (𝕎 R)) ≠ 0 := by
simpa using (IsFractionRing.injective (𝕎 R) (FractionRing (𝕎 R))).ne (WittVector.p_nonzero _ _)
#align witt_vector.fraction_ring.p_nonzero WittVector.FractionRing.p_nonzero
variable {p R}
-- Porting note: `ghost_calc` failure: `simp only []` and the manual instances had to be added.
| Mathlib/RingTheory/WittVector/Identities.lean | 103 | 111 | theorem verschiebung_mul_frobenius (x y : 𝕎 R) :
verschiebung (x * frobenius y) = verschiebung x * y := by |
have : IsPoly₂ p fun {R} [Rcr : CommRing R] x y ↦ verschiebung (x * frobenius y) :=
IsPoly.comp₂ (hg := verschiebung_isPoly)
(hf := IsPoly₂.comp (hh := mulIsPoly₂) (hf := idIsPolyI' p) (hg := frobenius_isPoly p))
have : IsPoly₂ p fun {R} [CommRing R] x y ↦ verschiebung x * y :=
IsPoly₂.comp (hh := mulIsPoly₂) (hf := verschiebung_isPoly) (hg := idIsPolyI' p)
ghost_calc x y
rintro ⟨⟩ <;> ghost_simp [mul_assoc]
| 2,003 |
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"
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.
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
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)
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]
#align witt_vector.coeff_p_pow WittVector.coeff_p_pow
theorem coeff_p_pow_eq_zero [CharP R p] {i j : ℕ} (hj : j ≠ i) : ((p : 𝕎 R) ^ i).coeff j = 0 := by
induction' i with i hi generalizing j
· rw [pow_zero, one_coeff_eq_of_pos]
exact Nat.pos_of_ne_zero hj
· rw [pow_succ, ← frobenius_verschiebung, coeff_frobenius_charP]
cases j
· rw [verschiebung_coeff_zero, zero_pow hp.out.ne_zero]
· rw [verschiebung_coeff_succ, hi (ne_of_apply_ne _ hj), zero_pow hp.out.ne_zero]
#align witt_vector.coeff_p_pow_eq_zero WittVector.coeff_p_pow_eq_zero
theorem coeff_p [CharP R p] (i : ℕ) : (p : 𝕎 R).coeff i = if i = 1 then 1 else 0 := by
split_ifs with hi
· simpa only [hi, pow_one] using coeff_p_pow p R 1
· simpa only [pow_one] using coeff_p_pow_eq_zero p R hi
#align witt_vector.coeff_p WittVector.coeff_p
@[simp]
theorem coeff_p_zero [CharP R p] : (p : 𝕎 R).coeff 0 = 0 := by
rw [coeff_p, if_neg]
exact zero_ne_one
#align witt_vector.coeff_p_zero WittVector.coeff_p_zero
@[simp]
theorem coeff_p_one [CharP R p] : (p : 𝕎 R).coeff 1 = 1 := by rw [coeff_p, if_pos rfl]
#align witt_vector.coeff_p_one WittVector.coeff_p_one
theorem p_nonzero [Nontrivial R] [CharP R p] : (p : 𝕎 R) ≠ 0 := by
intro h
simpa only [h, zero_coeff, zero_ne_one] using coeff_p_one p R
#align witt_vector.p_nonzero WittVector.p_nonzero
theorem FractionRing.p_nonzero [Nontrivial R] [CharP R p] : (p : FractionRing (𝕎 R)) ≠ 0 := by
simpa using (IsFractionRing.injective (𝕎 R) (FractionRing (𝕎 R))).ne (WittVector.p_nonzero _ _)
#align witt_vector.fraction_ring.p_nonzero WittVector.FractionRing.p_nonzero
variable {p R}
-- Porting note: `ghost_calc` failure: `simp only []` and the manual instances had to be added.
theorem verschiebung_mul_frobenius (x y : 𝕎 R) :
verschiebung (x * frobenius y) = verschiebung x * y := by
have : IsPoly₂ p fun {R} [Rcr : CommRing R] x y ↦ verschiebung (x * frobenius y) :=
IsPoly.comp₂ (hg := verschiebung_isPoly)
(hf := IsPoly₂.comp (hh := mulIsPoly₂) (hf := idIsPolyI' p) (hg := frobenius_isPoly p))
have : IsPoly₂ p fun {R} [CommRing R] x y ↦ verschiebung x * y :=
IsPoly₂.comp (hh := mulIsPoly₂) (hf := verschiebung_isPoly) (hg := idIsPolyI' p)
ghost_calc x y
rintro ⟨⟩ <;> ghost_simp [mul_assoc]
#align witt_vector.verschiebung_mul_frobenius WittVector.verschiebung_mul_frobenius
| Mathlib/RingTheory/WittVector/Identities.lean | 114 | 116 | theorem mul_charP_coeff_zero [CharP R p] (x : 𝕎 R) : (x * p).coeff 0 = 0 := by |
rw [← frobenius_verschiebung, coeff_frobenius_charP, verschiebung_coeff_zero,
zero_pow hp.out.ne_zero]
| 2,003 |
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"
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.
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
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)
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]
#align witt_vector.coeff_p_pow WittVector.coeff_p_pow
theorem coeff_p_pow_eq_zero [CharP R p] {i j : ℕ} (hj : j ≠ i) : ((p : 𝕎 R) ^ i).coeff j = 0 := by
induction' i with i hi generalizing j
· rw [pow_zero, one_coeff_eq_of_pos]
exact Nat.pos_of_ne_zero hj
· rw [pow_succ, ← frobenius_verschiebung, coeff_frobenius_charP]
cases j
· rw [verschiebung_coeff_zero, zero_pow hp.out.ne_zero]
· rw [verschiebung_coeff_succ, hi (ne_of_apply_ne _ hj), zero_pow hp.out.ne_zero]
#align witt_vector.coeff_p_pow_eq_zero WittVector.coeff_p_pow_eq_zero
theorem coeff_p [CharP R p] (i : ℕ) : (p : 𝕎 R).coeff i = if i = 1 then 1 else 0 := by
split_ifs with hi
· simpa only [hi, pow_one] using coeff_p_pow p R 1
· simpa only [pow_one] using coeff_p_pow_eq_zero p R hi
#align witt_vector.coeff_p WittVector.coeff_p
@[simp]
theorem coeff_p_zero [CharP R p] : (p : 𝕎 R).coeff 0 = 0 := by
rw [coeff_p, if_neg]
exact zero_ne_one
#align witt_vector.coeff_p_zero WittVector.coeff_p_zero
@[simp]
theorem coeff_p_one [CharP R p] : (p : 𝕎 R).coeff 1 = 1 := by rw [coeff_p, if_pos rfl]
#align witt_vector.coeff_p_one WittVector.coeff_p_one
theorem p_nonzero [Nontrivial R] [CharP R p] : (p : 𝕎 R) ≠ 0 := by
intro h
simpa only [h, zero_coeff, zero_ne_one] using coeff_p_one p R
#align witt_vector.p_nonzero WittVector.p_nonzero
theorem FractionRing.p_nonzero [Nontrivial R] [CharP R p] : (p : FractionRing (𝕎 R)) ≠ 0 := by
simpa using (IsFractionRing.injective (𝕎 R) (FractionRing (𝕎 R))).ne (WittVector.p_nonzero _ _)
#align witt_vector.fraction_ring.p_nonzero WittVector.FractionRing.p_nonzero
variable {p R}
-- Porting note: `ghost_calc` failure: `simp only []` and the manual instances had to be added.
theorem verschiebung_mul_frobenius (x y : 𝕎 R) :
verschiebung (x * frobenius y) = verschiebung x * y := by
have : IsPoly₂ p fun {R} [Rcr : CommRing R] x y ↦ verschiebung (x * frobenius y) :=
IsPoly.comp₂ (hg := verschiebung_isPoly)
(hf := IsPoly₂.comp (hh := mulIsPoly₂) (hf := idIsPolyI' p) (hg := frobenius_isPoly p))
have : IsPoly₂ p fun {R} [CommRing R] x y ↦ verschiebung x * y :=
IsPoly₂.comp (hh := mulIsPoly₂) (hf := verschiebung_isPoly) (hg := idIsPolyI' p)
ghost_calc x y
rintro ⟨⟩ <;> ghost_simp [mul_assoc]
#align witt_vector.verschiebung_mul_frobenius WittVector.verschiebung_mul_frobenius
theorem mul_charP_coeff_zero [CharP R p] (x : 𝕎 R) : (x * p).coeff 0 = 0 := by
rw [← frobenius_verschiebung, coeff_frobenius_charP, verschiebung_coeff_zero,
zero_pow hp.out.ne_zero]
#align witt_vector.mul_char_p_coeff_zero WittVector.mul_charP_coeff_zero
| Mathlib/RingTheory/WittVector/Identities.lean | 119 | 121 | theorem mul_charP_coeff_succ [CharP R p] (x : 𝕎 R) (i : ℕ) :
(x * p).coeff (i + 1) = x.coeff i ^ p := by |
rw [← frobenius_verschiebung, coeff_frobenius_charP, verschiebung_coeff_succ]
| 2,003 |
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"
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.
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
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)
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]
#align witt_vector.coeff_p_pow WittVector.coeff_p_pow
theorem coeff_p_pow_eq_zero [CharP R p] {i j : ℕ} (hj : j ≠ i) : ((p : 𝕎 R) ^ i).coeff j = 0 := by
induction' i with i hi generalizing j
· rw [pow_zero, one_coeff_eq_of_pos]
exact Nat.pos_of_ne_zero hj
· rw [pow_succ, ← frobenius_verschiebung, coeff_frobenius_charP]
cases j
· rw [verschiebung_coeff_zero, zero_pow hp.out.ne_zero]
· rw [verschiebung_coeff_succ, hi (ne_of_apply_ne _ hj), zero_pow hp.out.ne_zero]
#align witt_vector.coeff_p_pow_eq_zero WittVector.coeff_p_pow_eq_zero
theorem coeff_p [CharP R p] (i : ℕ) : (p : 𝕎 R).coeff i = if i = 1 then 1 else 0 := by
split_ifs with hi
· simpa only [hi, pow_one] using coeff_p_pow p R 1
· simpa only [pow_one] using coeff_p_pow_eq_zero p R hi
#align witt_vector.coeff_p WittVector.coeff_p
@[simp]
theorem coeff_p_zero [CharP R p] : (p : 𝕎 R).coeff 0 = 0 := by
rw [coeff_p, if_neg]
exact zero_ne_one
#align witt_vector.coeff_p_zero WittVector.coeff_p_zero
@[simp]
theorem coeff_p_one [CharP R p] : (p : 𝕎 R).coeff 1 = 1 := by rw [coeff_p, if_pos rfl]
#align witt_vector.coeff_p_one WittVector.coeff_p_one
theorem p_nonzero [Nontrivial R] [CharP R p] : (p : 𝕎 R) ≠ 0 := by
intro h
simpa only [h, zero_coeff, zero_ne_one] using coeff_p_one p R
#align witt_vector.p_nonzero WittVector.p_nonzero
theorem FractionRing.p_nonzero [Nontrivial R] [CharP R p] : (p : FractionRing (𝕎 R)) ≠ 0 := by
simpa using (IsFractionRing.injective (𝕎 R) (FractionRing (𝕎 R))).ne (WittVector.p_nonzero _ _)
#align witt_vector.fraction_ring.p_nonzero WittVector.FractionRing.p_nonzero
variable {p R}
-- Porting note: `ghost_calc` failure: `simp only []` and the manual instances had to be added.
theorem verschiebung_mul_frobenius (x y : 𝕎 R) :
verschiebung (x * frobenius y) = verschiebung x * y := by
have : IsPoly₂ p fun {R} [Rcr : CommRing R] x y ↦ verschiebung (x * frobenius y) :=
IsPoly.comp₂ (hg := verschiebung_isPoly)
(hf := IsPoly₂.comp (hh := mulIsPoly₂) (hf := idIsPolyI' p) (hg := frobenius_isPoly p))
have : IsPoly₂ p fun {R} [CommRing R] x y ↦ verschiebung x * y :=
IsPoly₂.comp (hh := mulIsPoly₂) (hf := verschiebung_isPoly) (hg := idIsPolyI' p)
ghost_calc x y
rintro ⟨⟩ <;> ghost_simp [mul_assoc]
#align witt_vector.verschiebung_mul_frobenius WittVector.verschiebung_mul_frobenius
theorem mul_charP_coeff_zero [CharP R p] (x : 𝕎 R) : (x * p).coeff 0 = 0 := by
rw [← frobenius_verschiebung, coeff_frobenius_charP, verschiebung_coeff_zero,
zero_pow hp.out.ne_zero]
#align witt_vector.mul_char_p_coeff_zero WittVector.mul_charP_coeff_zero
theorem mul_charP_coeff_succ [CharP R p] (x : 𝕎 R) (i : ℕ) :
(x * p).coeff (i + 1) = x.coeff i ^ p := by
rw [← frobenius_verschiebung, coeff_frobenius_charP, verschiebung_coeff_succ]
#align witt_vector.mul_char_p_coeff_succ WittVector.mul_charP_coeff_succ
| Mathlib/RingTheory/WittVector/Identities.lean | 124 | 127 | theorem verschiebung_frobenius [CharP R p] (x : 𝕎 R) : verschiebung (frobenius x) = x * p := by |
ext ⟨i⟩
· rw [mul_charP_coeff_zero, verschiebung_coeff_zero]
· rw [mul_charP_coeff_succ, verschiebung_coeff_succ, coeff_frobenius_charP]
| 2,003 |
import Mathlib.RingTheory.WittVector.Identities
#align_import ring_theory.witt_vector.domain from "leanprover-community/mathlib"@"b1d911acd60ab198808e853292106ee352b648ea"
noncomputable section
open scoped Classical
namespace WittVector
open Function
variable {p : ℕ} {R : Type*}
local notation "𝕎" => WittVector p -- type as `\bbW`
def shift (x : 𝕎 R) (n : ℕ) : 𝕎 R :=
@mk' p R fun i => x.coeff (n + i)
#align witt_vector.shift WittVector.shift
theorem shift_coeff (x : 𝕎 R) (n k : ℕ) : (x.shift n).coeff k = x.coeff (n + k) :=
rfl
#align witt_vector.shift_coeff WittVector.shift_coeff
variable [hp : Fact p.Prime] [CommRing R]
| Mathlib/RingTheory/WittVector/Domain.lean | 69 | 76 | theorem verschiebung_shift (x : 𝕎 R) (k : ℕ) (h : ∀ i < k + 1, x.coeff i = 0) :
verschiebung (x.shift k.succ) = x.shift k := by |
ext ⟨j⟩
· rw [verschiebung_coeff_zero, shift_coeff, h]
apply Nat.lt_succ_self
· simp only [verschiebung_coeff_succ, shift]
congr 1
rw [Nat.add_succ, add_comm, Nat.add_succ, add_comm]
| 2,004 |
import Mathlib.RingTheory.WittVector.Identities
#align_import ring_theory.witt_vector.domain from "leanprover-community/mathlib"@"b1d911acd60ab198808e853292106ee352b648ea"
noncomputable section
open scoped Classical
namespace WittVector
open Function
variable {p : ℕ} {R : Type*}
local notation "𝕎" => WittVector p -- type as `\bbW`
def shift (x : 𝕎 R) (n : ℕ) : 𝕎 R :=
@mk' p R fun i => x.coeff (n + i)
#align witt_vector.shift WittVector.shift
theorem shift_coeff (x : 𝕎 R) (n k : ℕ) : (x.shift n).coeff k = x.coeff (n + k) :=
rfl
#align witt_vector.shift_coeff WittVector.shift_coeff
variable [hp : Fact p.Prime] [CommRing R]
theorem verschiebung_shift (x : 𝕎 R) (k : ℕ) (h : ∀ i < k + 1, x.coeff i = 0) :
verschiebung (x.shift k.succ) = x.shift k := by
ext ⟨j⟩
· rw [verschiebung_coeff_zero, shift_coeff, h]
apply Nat.lt_succ_self
· simp only [verschiebung_coeff_succ, shift]
congr 1
rw [Nat.add_succ, add_comm, Nat.add_succ, add_comm]
#align witt_vector.verschiebung_shift WittVector.verschiebung_shift
| Mathlib/RingTheory/WittVector/Domain.lean | 79 | 85 | theorem eq_iterate_verschiebung {x : 𝕎 R} {n : ℕ} (h : ∀ i < n, x.coeff i = 0) :
x = verschiebung^[n] (x.shift n) := by |
induction' n with k ih
· cases x; simp [shift]
· dsimp; rw [verschiebung_shift]
· exact ih fun i hi => h _ (hi.trans (Nat.lt_succ_self _))
· exact h
| 2,004 |
import Mathlib.RingTheory.WittVector.Identities
#align_import ring_theory.witt_vector.domain from "leanprover-community/mathlib"@"b1d911acd60ab198808e853292106ee352b648ea"
noncomputable section
open scoped Classical
namespace WittVector
open Function
variable {p : ℕ} {R : Type*}
local notation "𝕎" => WittVector p -- type as `\bbW`
def shift (x : 𝕎 R) (n : ℕ) : 𝕎 R :=
@mk' p R fun i => x.coeff (n + i)
#align witt_vector.shift WittVector.shift
theorem shift_coeff (x : 𝕎 R) (n k : ℕ) : (x.shift n).coeff k = x.coeff (n + k) :=
rfl
#align witt_vector.shift_coeff WittVector.shift_coeff
variable [hp : Fact p.Prime] [CommRing R]
theorem verschiebung_shift (x : 𝕎 R) (k : ℕ) (h : ∀ i < k + 1, x.coeff i = 0) :
verschiebung (x.shift k.succ) = x.shift k := by
ext ⟨j⟩
· rw [verschiebung_coeff_zero, shift_coeff, h]
apply Nat.lt_succ_self
· simp only [verschiebung_coeff_succ, shift]
congr 1
rw [Nat.add_succ, add_comm, Nat.add_succ, add_comm]
#align witt_vector.verschiebung_shift WittVector.verschiebung_shift
theorem eq_iterate_verschiebung {x : 𝕎 R} {n : ℕ} (h : ∀ i < n, x.coeff i = 0) :
x = verschiebung^[n] (x.shift n) := by
induction' n with k ih
· cases x; simp [shift]
· dsimp; rw [verschiebung_shift]
· exact ih fun i hi => h _ (hi.trans (Nat.lt_succ_self _))
· exact h
#align witt_vector.eq_iterate_verschiebung WittVector.eq_iterate_verschiebung
| Mathlib/RingTheory/WittVector/Domain.lean | 88 | 98 | theorem verschiebung_nonzero {x : 𝕎 R} (hx : x ≠ 0) :
∃ n : ℕ, ∃ x' : 𝕎 R, x'.coeff 0 ≠ 0 ∧ x = verschiebung^[n] x' := by |
have hex : ∃ k : ℕ, x.coeff k ≠ 0 := by
by_contra! hall
apply hx
ext i
simp only [hall, zero_coeff]
let n := Nat.find hex
use n, x.shift n
refine ⟨Nat.find_spec hex, eq_iterate_verschiebung fun i hi => not_not.mp ?_⟩
exact Nat.find_min hex hi
| 2,004 |
import Mathlib.RingTheory.WittVector.Domain
import Mathlib.RingTheory.WittVector.MulCoeff
import Mathlib.RingTheory.DiscreteValuationRing.Basic
import Mathlib.Tactic.LinearCombination
#align_import ring_theory.witt_vector.discrete_valuation_ring from "leanprover-community/mathlib"@"c163ec99dfc664628ca15d215fce0a5b9c265b68"
noncomputable section
namespace WittVector
variable {p : ℕ} [hp : Fact p.Prime]
local notation "𝕎" => WittVector p
section PerfectRing
variable {k : Type*} [CommRing k] [CharP k p] [PerfectRing k p]
| Mathlib/RingTheory/WittVector/DiscreteValuationRing.lean | 121 | 135 | theorem exists_eq_pow_p_mul (a : 𝕎 k) (ha : a ≠ 0) :
∃ (m : ℕ) (b : 𝕎 k), b.coeff 0 ≠ 0 ∧ a = (p : 𝕎 k) ^ m * b := by |
obtain ⟨m, c, hc, hcm⟩ := WittVector.verschiebung_nonzero ha
obtain ⟨b, rfl⟩ := (frobenius_bijective p k).surjective.iterate m c
rw [WittVector.iterate_frobenius_coeff] at hc
have := congr_fun (WittVector.verschiebung_frobenius_comm.comp_iterate m) b
simp only [Function.comp_apply] at this
rw [← this] at hcm
refine ⟨m, b, ?_, ?_⟩
· contrapose! hc
simp [hc, zero_pow $ pow_ne_zero _ hp.out.ne_zero]
· simp_rw [← mul_left_iterate (p : 𝕎 k) m]
convert hcm using 2
ext1 x
rw [mul_comm, ← WittVector.verschiebung_frobenius x]; rfl
| 2,005 |
import Mathlib.RingTheory.WittVector.Truncated
import Mathlib.RingTheory.WittVector.Identities
import Mathlib.NumberTheory.Padics.RingHoms
#align_import ring_theory.witt_vector.compare from "leanprover-community/mathlib"@"168ad7fc5d8173ad38be9767a22d50b8ecf1cd00"
noncomputable section
variable {p : ℕ} [hp : Fact p.Prime]
local notation "𝕎" => WittVector p
namespace TruncatedWittVector
variable (p) (n : ℕ) (R : Type*) [CommRing R]
| Mathlib/RingTheory/WittVector/Compare.lean | 43 | 53 | theorem eq_of_le_of_cast_pow_eq_zero [CharP R p] (i : ℕ) (hin : i ≤ n)
(hpi : (p : TruncatedWittVector p n R) ^ i = 0) : i = n := by |
contrapose! hpi
replace hin := lt_of_le_of_ne hin hpi; clear hpi
have : (p : TruncatedWittVector p n R) ^ i = WittVector.truncate n ((p : 𝕎 R) ^ i) := by
rw [RingHom.map_pow, map_natCast]
rw [this, ne_eq, ext_iff, not_forall]; clear this
use ⟨i, hin⟩
rw [WittVector.coeff_truncate, coeff_zero, Fin.val_mk, WittVector.coeff_p_pow]
haveI : Nontrivial R := CharP.nontrivial_of_char_ne_one hp.1.ne_one
exact one_ne_zero
| 2,006 |
import Mathlib.RingTheory.WittVector.Truncated
import Mathlib.RingTheory.WittVector.Identities
import Mathlib.NumberTheory.Padics.RingHoms
#align_import ring_theory.witt_vector.compare from "leanprover-community/mathlib"@"168ad7fc5d8173ad38be9767a22d50b8ecf1cd00"
noncomputable section
variable {p : ℕ} [hp : Fact p.Prime]
local notation "𝕎" => WittVector p
namespace TruncatedWittVector
variable (p) (n : ℕ) (R : Type*) [CommRing R]
theorem eq_of_le_of_cast_pow_eq_zero [CharP R p] (i : ℕ) (hin : i ≤ n)
(hpi : (p : TruncatedWittVector p n R) ^ i = 0) : i = n := by
contrapose! hpi
replace hin := lt_of_le_of_ne hin hpi; clear hpi
have : (p : TruncatedWittVector p n R) ^ i = WittVector.truncate n ((p : 𝕎 R) ^ i) := by
rw [RingHom.map_pow, map_natCast]
rw [this, ne_eq, ext_iff, not_forall]; clear this
use ⟨i, hin⟩
rw [WittVector.coeff_truncate, coeff_zero, Fin.val_mk, WittVector.coeff_p_pow]
haveI : Nontrivial R := CharP.nontrivial_of_char_ne_one hp.1.ne_one
exact one_ne_zero
#align truncated_witt_vector.eq_of_le_of_cast_pow_eq_zero TruncatedWittVector.eq_of_le_of_cast_pow_eq_zero
section Iso
variable {R}
| Mathlib/RingTheory/WittVector/Compare.lean | 60 | 61 | theorem card_zmod : Fintype.card (TruncatedWittVector p n (ZMod p)) = p ^ n := by |
rw [card, ZMod.card]
| 2,006 |
import Mathlib.RingTheory.WittVector.Truncated
import Mathlib.RingTheory.WittVector.Identities
import Mathlib.NumberTheory.Padics.RingHoms
#align_import ring_theory.witt_vector.compare from "leanprover-community/mathlib"@"168ad7fc5d8173ad38be9767a22d50b8ecf1cd00"
noncomputable section
variable {p : ℕ} [hp : Fact p.Prime]
local notation "𝕎" => WittVector p
namespace TruncatedWittVector
variable (p) (n : ℕ) (R : Type*) [CommRing R]
theorem eq_of_le_of_cast_pow_eq_zero [CharP R p] (i : ℕ) (hin : i ≤ n)
(hpi : (p : TruncatedWittVector p n R) ^ i = 0) : i = n := by
contrapose! hpi
replace hin := lt_of_le_of_ne hin hpi; clear hpi
have : (p : TruncatedWittVector p n R) ^ i = WittVector.truncate n ((p : 𝕎 R) ^ i) := by
rw [RingHom.map_pow, map_natCast]
rw [this, ne_eq, ext_iff, not_forall]; clear this
use ⟨i, hin⟩
rw [WittVector.coeff_truncate, coeff_zero, Fin.val_mk, WittVector.coeff_p_pow]
haveI : Nontrivial R := CharP.nontrivial_of_char_ne_one hp.1.ne_one
exact one_ne_zero
#align truncated_witt_vector.eq_of_le_of_cast_pow_eq_zero TruncatedWittVector.eq_of_le_of_cast_pow_eq_zero
section Iso
variable {R}
theorem card_zmod : Fintype.card (TruncatedWittVector p n (ZMod p)) = p ^ n := by
rw [card, ZMod.card]
#align truncated_witt_vector.card_zmod TruncatedWittVector.card_zmod
theorem charP_zmod : CharP (TruncatedWittVector p n (ZMod p)) (p ^ n) :=
charP_of_prime_pow_injective _ _ _ (card_zmod _ _) (eq_of_le_of_cast_pow_eq_zero p n (ZMod p))
#align truncated_witt_vector.char_p_zmod TruncatedWittVector.charP_zmod
attribute [local instance] charP_zmod
def zmodEquivTrunc : ZMod (p ^ n) ≃+* TruncatedWittVector p n (ZMod p) :=
ZMod.ringEquiv (TruncatedWittVector p n (ZMod p)) (card_zmod _ _)
#align truncated_witt_vector.zmod_equiv_trunc TruncatedWittVector.zmodEquivTrunc
theorem zmodEquivTrunc_apply {x : ZMod (p ^ n)} :
zmodEquivTrunc p n x = ZMod.castHom (by rfl) (TruncatedWittVector p n (ZMod p)) x :=
rfl
#align truncated_witt_vector.zmod_equiv_trunc_apply TruncatedWittVector.zmodEquivTrunc_apply
theorem commutes {m : ℕ} (hm : n ≤ m) :
(truncate hm).comp (zmodEquivTrunc p m).toRingHom =
(zmodEquivTrunc p n).toRingHom.comp (ZMod.castHom (pow_dvd_pow p hm) _) :=
RingHom.ext_zmod _ _
#align truncated_witt_vector.commutes TruncatedWittVector.commutes
theorem commutes' {m : ℕ} (hm : n ≤ m) (x : ZMod (p ^ m)) :
truncate hm (zmodEquivTrunc p m x) = zmodEquivTrunc p n (ZMod.castHom (pow_dvd_pow p hm) _ x) :=
show (truncate hm).comp (zmodEquivTrunc p m).toRingHom x = _ by rw [commutes _ _ hm]; rfl
#align truncated_witt_vector.commutes' TruncatedWittVector.commutes'
| Mathlib/RingTheory/WittVector/Compare.lean | 107 | 112 | theorem commutes_symm' {m : ℕ} (hm : n ≤ m) (x : TruncatedWittVector p m (ZMod p)) :
(zmodEquivTrunc p n).symm (truncate hm x) =
ZMod.castHom (pow_dvd_pow p hm) _ ((zmodEquivTrunc p m).symm x) := by |
apply (zmodEquivTrunc p n).injective
rw [← commutes' _ _ hm]
simp
| 2,006 |
import Mathlib.RingTheory.WittVector.Truncated
import Mathlib.RingTheory.WittVector.Identities
import Mathlib.NumberTheory.Padics.RingHoms
#align_import ring_theory.witt_vector.compare from "leanprover-community/mathlib"@"168ad7fc5d8173ad38be9767a22d50b8ecf1cd00"
noncomputable section
variable {p : ℕ} [hp : Fact p.Prime]
local notation "𝕎" => WittVector p
namespace TruncatedWittVector
variable (p) (n : ℕ) (R : Type*) [CommRing R]
theorem eq_of_le_of_cast_pow_eq_zero [CharP R p] (i : ℕ) (hin : i ≤ n)
(hpi : (p : TruncatedWittVector p n R) ^ i = 0) : i = n := by
contrapose! hpi
replace hin := lt_of_le_of_ne hin hpi; clear hpi
have : (p : TruncatedWittVector p n R) ^ i = WittVector.truncate n ((p : 𝕎 R) ^ i) := by
rw [RingHom.map_pow, map_natCast]
rw [this, ne_eq, ext_iff, not_forall]; clear this
use ⟨i, hin⟩
rw [WittVector.coeff_truncate, coeff_zero, Fin.val_mk, WittVector.coeff_p_pow]
haveI : Nontrivial R := CharP.nontrivial_of_char_ne_one hp.1.ne_one
exact one_ne_zero
#align truncated_witt_vector.eq_of_le_of_cast_pow_eq_zero TruncatedWittVector.eq_of_le_of_cast_pow_eq_zero
section Iso
variable {R}
theorem card_zmod : Fintype.card (TruncatedWittVector p n (ZMod p)) = p ^ n := by
rw [card, ZMod.card]
#align truncated_witt_vector.card_zmod TruncatedWittVector.card_zmod
theorem charP_zmod : CharP (TruncatedWittVector p n (ZMod p)) (p ^ n) :=
charP_of_prime_pow_injective _ _ _ (card_zmod _ _) (eq_of_le_of_cast_pow_eq_zero p n (ZMod p))
#align truncated_witt_vector.char_p_zmod TruncatedWittVector.charP_zmod
attribute [local instance] charP_zmod
def zmodEquivTrunc : ZMod (p ^ n) ≃+* TruncatedWittVector p n (ZMod p) :=
ZMod.ringEquiv (TruncatedWittVector p n (ZMod p)) (card_zmod _ _)
#align truncated_witt_vector.zmod_equiv_trunc TruncatedWittVector.zmodEquivTrunc
theorem zmodEquivTrunc_apply {x : ZMod (p ^ n)} :
zmodEquivTrunc p n x = ZMod.castHom (by rfl) (TruncatedWittVector p n (ZMod p)) x :=
rfl
#align truncated_witt_vector.zmod_equiv_trunc_apply TruncatedWittVector.zmodEquivTrunc_apply
theorem commutes {m : ℕ} (hm : n ≤ m) :
(truncate hm).comp (zmodEquivTrunc p m).toRingHom =
(zmodEquivTrunc p n).toRingHom.comp (ZMod.castHom (pow_dvd_pow p hm) _) :=
RingHom.ext_zmod _ _
#align truncated_witt_vector.commutes TruncatedWittVector.commutes
theorem commutes' {m : ℕ} (hm : n ≤ m) (x : ZMod (p ^ m)) :
truncate hm (zmodEquivTrunc p m x) = zmodEquivTrunc p n (ZMod.castHom (pow_dvd_pow p hm) _ x) :=
show (truncate hm).comp (zmodEquivTrunc p m).toRingHom x = _ by rw [commutes _ _ hm]; rfl
#align truncated_witt_vector.commutes' TruncatedWittVector.commutes'
theorem commutes_symm' {m : ℕ} (hm : n ≤ m) (x : TruncatedWittVector p m (ZMod p)) :
(zmodEquivTrunc p n).symm (truncate hm x) =
ZMod.castHom (pow_dvd_pow p hm) _ ((zmodEquivTrunc p m).symm x) := by
apply (zmodEquivTrunc p n).injective
rw [← commutes' _ _ hm]
simp
#align truncated_witt_vector.commutes_symm' TruncatedWittVector.commutes_symm'
| Mathlib/RingTheory/WittVector/Compare.lean | 127 | 130 | theorem commutes_symm {m : ℕ} (hm : n ≤ m) :
(zmodEquivTrunc p n).symm.toRingHom.comp (truncate hm) =
(ZMod.castHom (pow_dvd_pow p hm) _).comp (zmodEquivTrunc p m).symm.toRingHom := by |
ext; apply commutes_symm'
| 2,006 |
import Mathlib.Algebra.CharP.Pi
import Mathlib.Algebra.CharP.Quotient
import Mathlib.Algebra.CharP.Subring
import Mathlib.Algebra.Ring.Pi
import Mathlib.Analysis.SpecialFunctions.Pow.NNReal
import Mathlib.FieldTheory.Perfect
import Mathlib.RingTheory.Localization.FractionRing
import Mathlib.Algebra.Ring.Subring.Basic
import Mathlib.RingTheory.Valuation.Integers
#align_import ring_theory.perfection from "leanprover-community/mathlib"@"0b9eaaa7686280fad8cce467f5c3c57ee6ce77f8"
universe u₁ u₂ u₃ u₄
open scoped NNReal
def Monoid.perfection (M : Type u₁) [CommMonoid M] (p : ℕ) : Submonoid (ℕ → M) where
carrier := { f | ∀ n, f (n + 1) ^ p = f n }
one_mem' _ := one_pow _
mul_mem' hf hg n := (mul_pow _ _ _).trans <| congr_arg₂ _ (hf n) (hg n)
#align monoid.perfection Monoid.perfection
def Ring.perfectionSubsemiring (R : Type u₁) [CommSemiring R] (p : ℕ) [hp : Fact p.Prime]
[CharP R p] : Subsemiring (ℕ → R) :=
{ Monoid.perfection R p with
zero_mem' := fun _ ↦ zero_pow hp.1.ne_zero
add_mem' := fun hf hg n => (frobenius_add R p _ _).trans <| congr_arg₂ _ (hf n) (hg n) }
#align ring.perfection_subsemiring Ring.perfectionSubsemiring
def Ring.perfectionSubring (R : Type u₁) [CommRing R] (p : ℕ) [hp : Fact p.Prime] [CharP R p] :
Subring (ℕ → R) :=
(Ring.perfectionSubsemiring R p).toSubring fun n => by
simp_rw [← frobenius_def, Pi.neg_apply, Pi.one_apply, RingHom.map_neg, RingHom.map_one]
#align ring.perfection_subring Ring.perfectionSubring
def Ring.Perfection (R : Type u₁) [CommSemiring R] (p : ℕ) : Type u₁ :=
{ f // ∀ n : ℕ, (f : ℕ → R) (n + 1) ^ p = f n }
#align ring.perfection Ring.Perfection
namespace Perfection
variable (R : Type u₁) [CommSemiring R] (p : ℕ) [hp : Fact p.Prime] [CharP R p]
instance commSemiring : CommSemiring (Ring.Perfection R p) :=
(Ring.perfectionSubsemiring R p).toCommSemiring
#align perfection.ring.perfection.comm_semiring Perfection.commSemiring
instance charP : CharP (Ring.Perfection R p) p :=
CharP.subsemiring (ℕ → R) p (Ring.perfectionSubsemiring R p)
#align perfection.char_p Perfection.charP
instance ring (R : Type u₁) [CommRing R] [CharP R p] : Ring (Ring.Perfection R p) :=
(Ring.perfectionSubring R p).toRing
#align perfection.ring Perfection.ring
instance commRing (R : Type u₁) [CommRing R] [CharP R p] : CommRing (Ring.Perfection R p) :=
(Ring.perfectionSubring R p).toCommRing
#align perfection.comm_ring Perfection.commRing
instance : Inhabited (Ring.Perfection R p) := ⟨0⟩
def coeff (n : ℕ) : Ring.Perfection R p →+* R where
toFun f := f.1 n
map_one' := rfl
map_mul' _ _ := rfl
map_zero' := rfl
map_add' _ _ := rfl
#align perfection.coeff Perfection.coeff
variable {R p}
@[ext]
theorem ext {f g : Ring.Perfection R p} (h : ∀ n, coeff R p n f = coeff R p n g) : f = g :=
Subtype.eq <| funext h
#align perfection.ext Perfection.ext
variable (R p)
def pthRoot : Ring.Perfection R p →+* Ring.Perfection R p where
toFun f := ⟨fun n => coeff R p (n + 1) f, fun _ => f.2 _⟩
map_one' := rfl
map_mul' _ _ := rfl
map_zero' := rfl
map_add' _ _ := rfl
#align perfection.pth_root Perfection.pthRoot
variable {R p}
@[simp]
theorem coeff_mk (f : ℕ → R) (hf) (n : ℕ) : coeff R p n ⟨f, hf⟩ = f n := rfl
#align perfection.coeff_mk Perfection.coeff_mk
theorem coeff_pthRoot (f : Ring.Perfection R p) (n : ℕ) :
coeff R p n (pthRoot R p f) = coeff R p (n + 1) f := rfl
#align perfection.coeff_pth_root Perfection.coeff_pthRoot
| Mathlib/RingTheory/Perfection.lean | 129 | 130 | theorem coeff_pow_p (f : Ring.Perfection R p) (n : ℕ) :
coeff R p (n + 1) (f ^ p) = coeff R p n f := by | rw [RingHom.map_pow]; exact f.2 n
| 2,007 |
import Mathlib.Algebra.CharP.Pi
import Mathlib.Algebra.CharP.Quotient
import Mathlib.Algebra.CharP.Subring
import Mathlib.Algebra.Ring.Pi
import Mathlib.Analysis.SpecialFunctions.Pow.NNReal
import Mathlib.FieldTheory.Perfect
import Mathlib.RingTheory.Localization.FractionRing
import Mathlib.Algebra.Ring.Subring.Basic
import Mathlib.RingTheory.Valuation.Integers
#align_import ring_theory.perfection from "leanprover-community/mathlib"@"0b9eaaa7686280fad8cce467f5c3c57ee6ce77f8"
universe u₁ u₂ u₃ u₄
open scoped NNReal
def Monoid.perfection (M : Type u₁) [CommMonoid M] (p : ℕ) : Submonoid (ℕ → M) where
carrier := { f | ∀ n, f (n + 1) ^ p = f n }
one_mem' _ := one_pow _
mul_mem' hf hg n := (mul_pow _ _ _).trans <| congr_arg₂ _ (hf n) (hg n)
#align monoid.perfection Monoid.perfection
def Ring.perfectionSubsemiring (R : Type u₁) [CommSemiring R] (p : ℕ) [hp : Fact p.Prime]
[CharP R p] : Subsemiring (ℕ → R) :=
{ Monoid.perfection R p with
zero_mem' := fun _ ↦ zero_pow hp.1.ne_zero
add_mem' := fun hf hg n => (frobenius_add R p _ _).trans <| congr_arg₂ _ (hf n) (hg n) }
#align ring.perfection_subsemiring Ring.perfectionSubsemiring
def Ring.perfectionSubring (R : Type u₁) [CommRing R] (p : ℕ) [hp : Fact p.Prime] [CharP R p] :
Subring (ℕ → R) :=
(Ring.perfectionSubsemiring R p).toSubring fun n => by
simp_rw [← frobenius_def, Pi.neg_apply, Pi.one_apply, RingHom.map_neg, RingHom.map_one]
#align ring.perfection_subring Ring.perfectionSubring
def Ring.Perfection (R : Type u₁) [CommSemiring R] (p : ℕ) : Type u₁ :=
{ f // ∀ n : ℕ, (f : ℕ → R) (n + 1) ^ p = f n }
#align ring.perfection Ring.Perfection
namespace Perfection
variable (R : Type u₁) [CommSemiring R] (p : ℕ) [hp : Fact p.Prime] [CharP R p]
instance commSemiring : CommSemiring (Ring.Perfection R p) :=
(Ring.perfectionSubsemiring R p).toCommSemiring
#align perfection.ring.perfection.comm_semiring Perfection.commSemiring
instance charP : CharP (Ring.Perfection R p) p :=
CharP.subsemiring (ℕ → R) p (Ring.perfectionSubsemiring R p)
#align perfection.char_p Perfection.charP
instance ring (R : Type u₁) [CommRing R] [CharP R p] : Ring (Ring.Perfection R p) :=
(Ring.perfectionSubring R p).toRing
#align perfection.ring Perfection.ring
instance commRing (R : Type u₁) [CommRing R] [CharP R p] : CommRing (Ring.Perfection R p) :=
(Ring.perfectionSubring R p).toCommRing
#align perfection.comm_ring Perfection.commRing
instance : Inhabited (Ring.Perfection R p) := ⟨0⟩
def coeff (n : ℕ) : Ring.Perfection R p →+* R where
toFun f := f.1 n
map_one' := rfl
map_mul' _ _ := rfl
map_zero' := rfl
map_add' _ _ := rfl
#align perfection.coeff Perfection.coeff
variable {R p}
@[ext]
theorem ext {f g : Ring.Perfection R p} (h : ∀ n, coeff R p n f = coeff R p n g) : f = g :=
Subtype.eq <| funext h
#align perfection.ext Perfection.ext
variable (R p)
def pthRoot : Ring.Perfection R p →+* Ring.Perfection R p where
toFun f := ⟨fun n => coeff R p (n + 1) f, fun _ => f.2 _⟩
map_one' := rfl
map_mul' _ _ := rfl
map_zero' := rfl
map_add' _ _ := rfl
#align perfection.pth_root Perfection.pthRoot
variable {R p}
@[simp]
theorem coeff_mk (f : ℕ → R) (hf) (n : ℕ) : coeff R p n ⟨f, hf⟩ = f n := rfl
#align perfection.coeff_mk Perfection.coeff_mk
theorem coeff_pthRoot (f : Ring.Perfection R p) (n : ℕ) :
coeff R p n (pthRoot R p f) = coeff R p (n + 1) f := rfl
#align perfection.coeff_pth_root Perfection.coeff_pthRoot
theorem coeff_pow_p (f : Ring.Perfection R p) (n : ℕ) :
coeff R p (n + 1) (f ^ p) = coeff R p n f := by rw [RingHom.map_pow]; exact f.2 n
#align perfection.coeff_pow_p Perfection.coeff_pow_p
theorem coeff_pow_p' (f : Ring.Perfection R p) (n : ℕ) : coeff R p (n + 1) f ^ p = coeff R p n f :=
f.2 n
#align perfection.coeff_pow_p' Perfection.coeff_pow_p'
| Mathlib/RingTheory/Perfection.lean | 137 | 138 | theorem coeff_frobenius (f : Ring.Perfection R p) (n : ℕ) :
coeff R p (n + 1) (frobenius _ p f) = coeff R p n f := by | apply coeff_pow_p f n
| 2,007 |
import Mathlib.Algebra.CharP.Pi
import Mathlib.Algebra.CharP.Quotient
import Mathlib.Algebra.CharP.Subring
import Mathlib.Algebra.Ring.Pi
import Mathlib.Analysis.SpecialFunctions.Pow.NNReal
import Mathlib.FieldTheory.Perfect
import Mathlib.RingTheory.Localization.FractionRing
import Mathlib.Algebra.Ring.Subring.Basic
import Mathlib.RingTheory.Valuation.Integers
#align_import ring_theory.perfection from "leanprover-community/mathlib"@"0b9eaaa7686280fad8cce467f5c3c57ee6ce77f8"
universe u₁ u₂ u₃ u₄
open scoped NNReal
def Monoid.perfection (M : Type u₁) [CommMonoid M] (p : ℕ) : Submonoid (ℕ → M) where
carrier := { f | ∀ n, f (n + 1) ^ p = f n }
one_mem' _ := one_pow _
mul_mem' hf hg n := (mul_pow _ _ _).trans <| congr_arg₂ _ (hf n) (hg n)
#align monoid.perfection Monoid.perfection
def Ring.perfectionSubsemiring (R : Type u₁) [CommSemiring R] (p : ℕ) [hp : Fact p.Prime]
[CharP R p] : Subsemiring (ℕ → R) :=
{ Monoid.perfection R p with
zero_mem' := fun _ ↦ zero_pow hp.1.ne_zero
add_mem' := fun hf hg n => (frobenius_add R p _ _).trans <| congr_arg₂ _ (hf n) (hg n) }
#align ring.perfection_subsemiring Ring.perfectionSubsemiring
def Ring.perfectionSubring (R : Type u₁) [CommRing R] (p : ℕ) [hp : Fact p.Prime] [CharP R p] :
Subring (ℕ → R) :=
(Ring.perfectionSubsemiring R p).toSubring fun n => by
simp_rw [← frobenius_def, Pi.neg_apply, Pi.one_apply, RingHom.map_neg, RingHom.map_one]
#align ring.perfection_subring Ring.perfectionSubring
def Ring.Perfection (R : Type u₁) [CommSemiring R] (p : ℕ) : Type u₁ :=
{ f // ∀ n : ℕ, (f : ℕ → R) (n + 1) ^ p = f n }
#align ring.perfection Ring.Perfection
-- @[nolint has_nonempty_instance] -- Porting note(#5171): This linter does not exist yet.
structure PerfectionMap (p : ℕ) [Fact p.Prime] {R : Type u₁} [CommSemiring R] [CharP R p]
{P : Type u₂} [CommSemiring P] [CharP P p] [PerfectRing P p] (π : P →+* R) : Prop where
injective : ∀ ⦃x y : P⦄,
(∀ n, π (((frobeniusEquiv P p).symm)^[n] x) = π (((frobeniusEquiv P p).symm)^[n] y)) → x = y
surjective : ∀ f : ℕ → R, (∀ n, f (n + 1) ^ p = f n) → ∃ x : P, ∀ n,
π (((frobeniusEquiv P p).symm)^[n] x) = f n
#align perfection_map PerfectionMap
section Perfectoid
variable (K : Type u₁) [Field K] (v : Valuation K ℝ≥0)
variable (O : Type u₂) [CommRing O] [Algebra O K] (hv : v.Integers O)
variable (p : ℕ)
-- Porting note: Specified all arguments explicitly
@[nolint unusedArguments] -- Porting note(#5171): removed `nolint has_nonempty_instance`
def ModP (K : Type u₁) [Field K] (v : Valuation K ℝ≥0) (O : Type u₂) [CommRing O] [Algebra O K]
(_ : v.Integers O) (p : ℕ) :=
O ⧸ (Ideal.span {(p : O)} : Ideal O)
#align mod_p ModP
variable [hp : Fact p.Prime] [hvp : Fact (v p ≠ 1)]
namespace ModP
instance commRing : CommRing (ModP K v O hv p) :=
Ideal.Quotient.commRing (Ideal.span {(p : O)} : Ideal O)
instance charP : CharP (ModP K v O hv p) p :=
CharP.quotient O p <| mt hv.one_of_isUnit <| (map_natCast (algebraMap O K) p).symm ▸ hvp.1
instance : Nontrivial (ModP K v O hv p) :=
CharP.nontrivial_of_char_ne_one hp.1.ne_one
section Classical
attribute [local instance] Classical.dec
noncomputable def preVal (x : ModP K v O hv p) : ℝ≥0 :=
if x = 0 then 0 else v (algebraMap O K x.out')
#align mod_p.pre_val ModP.preVal
variable {K v O hv p}
| Mathlib/RingTheory/Perfection.lean | 406 | 413 | theorem preVal_mk {x : O} (hx : (Ideal.Quotient.mk _ x : ModP K v O hv p) ≠ 0) :
preVal K v O hv p (Ideal.Quotient.mk _ x) = v (algebraMap O K x) := by |
obtain ⟨r, hr⟩ : ∃ (a : O), a * (p : O) = (Quotient.mk'' x).out' - x :=
Ideal.mem_span_singleton'.1 <| Ideal.Quotient.eq.1 <| Quotient.sound' <| Quotient.mk_out' _
refine (if_neg hx).trans (v.map_eq_of_sub_lt <| lt_of_not_le ?_)
erw [← RingHom.map_sub, ← hr, hv.le_iff_dvd]
exact fun hprx =>
hx (Ideal.Quotient.eq_zero_iff_mem.2 <| Ideal.mem_span_singleton.2 <| dvd_of_mul_left_dvd hprx)
| 2,007 |
import Mathlib.Algebra.CharP.Pi
import Mathlib.Algebra.CharP.Quotient
import Mathlib.Algebra.CharP.Subring
import Mathlib.Algebra.Ring.Pi
import Mathlib.Analysis.SpecialFunctions.Pow.NNReal
import Mathlib.FieldTheory.Perfect
import Mathlib.RingTheory.Localization.FractionRing
import Mathlib.Algebra.Ring.Subring.Basic
import Mathlib.RingTheory.Valuation.Integers
#align_import ring_theory.perfection from "leanprover-community/mathlib"@"0b9eaaa7686280fad8cce467f5c3c57ee6ce77f8"
universe u₁ u₂ u₃ u₄
open scoped NNReal
def Monoid.perfection (M : Type u₁) [CommMonoid M] (p : ℕ) : Submonoid (ℕ → M) where
carrier := { f | ∀ n, f (n + 1) ^ p = f n }
one_mem' _ := one_pow _
mul_mem' hf hg n := (mul_pow _ _ _).trans <| congr_arg₂ _ (hf n) (hg n)
#align monoid.perfection Monoid.perfection
def Ring.perfectionSubsemiring (R : Type u₁) [CommSemiring R] (p : ℕ) [hp : Fact p.Prime]
[CharP R p] : Subsemiring (ℕ → R) :=
{ Monoid.perfection R p with
zero_mem' := fun _ ↦ zero_pow hp.1.ne_zero
add_mem' := fun hf hg n => (frobenius_add R p _ _).trans <| congr_arg₂ _ (hf n) (hg n) }
#align ring.perfection_subsemiring Ring.perfectionSubsemiring
def Ring.perfectionSubring (R : Type u₁) [CommRing R] (p : ℕ) [hp : Fact p.Prime] [CharP R p] :
Subring (ℕ → R) :=
(Ring.perfectionSubsemiring R p).toSubring fun n => by
simp_rw [← frobenius_def, Pi.neg_apply, Pi.one_apply, RingHom.map_neg, RingHom.map_one]
#align ring.perfection_subring Ring.perfectionSubring
def Ring.Perfection (R : Type u₁) [CommSemiring R] (p : ℕ) : Type u₁ :=
{ f // ∀ n : ℕ, (f : ℕ → R) (n + 1) ^ p = f n }
#align ring.perfection Ring.Perfection
-- @[nolint has_nonempty_instance] -- Porting note(#5171): This linter does not exist yet.
structure PerfectionMap (p : ℕ) [Fact p.Prime] {R : Type u₁} [CommSemiring R] [CharP R p]
{P : Type u₂} [CommSemiring P] [CharP P p] [PerfectRing P p] (π : P →+* R) : Prop where
injective : ∀ ⦃x y : P⦄,
(∀ n, π (((frobeniusEquiv P p).symm)^[n] x) = π (((frobeniusEquiv P p).symm)^[n] y)) → x = y
surjective : ∀ f : ℕ → R, (∀ n, f (n + 1) ^ p = f n) → ∃ x : P, ∀ n,
π (((frobeniusEquiv P p).symm)^[n] x) = f n
#align perfection_map PerfectionMap
section Perfectoid
variable (K : Type u₁) [Field K] (v : Valuation K ℝ≥0)
variable (O : Type u₂) [CommRing O] [Algebra O K] (hv : v.Integers O)
variable (p : ℕ)
-- Porting note: Specified all arguments explicitly
@[nolint unusedArguments] -- Porting note(#5171): removed `nolint has_nonempty_instance`
def ModP (K : Type u₁) [Field K] (v : Valuation K ℝ≥0) (O : Type u₂) [CommRing O] [Algebra O K]
(_ : v.Integers O) (p : ℕ) :=
O ⧸ (Ideal.span {(p : O)} : Ideal O)
#align mod_p ModP
variable [hp : Fact p.Prime] [hvp : Fact (v p ≠ 1)]
namespace ModP
instance commRing : CommRing (ModP K v O hv p) :=
Ideal.Quotient.commRing (Ideal.span {(p : O)} : Ideal O)
instance charP : CharP (ModP K v O hv p) p :=
CharP.quotient O p <| mt hv.one_of_isUnit <| (map_natCast (algebraMap O K) p).symm ▸ hvp.1
instance : Nontrivial (ModP K v O hv p) :=
CharP.nontrivial_of_char_ne_one hp.1.ne_one
section Classical
attribute [local instance] Classical.dec
noncomputable def preVal (x : ModP K v O hv p) : ℝ≥0 :=
if x = 0 then 0 else v (algebraMap O K x.out')
#align mod_p.pre_val ModP.preVal
variable {K v O hv p}
theorem preVal_mk {x : O} (hx : (Ideal.Quotient.mk _ x : ModP K v O hv p) ≠ 0) :
preVal K v O hv p (Ideal.Quotient.mk _ x) = v (algebraMap O K x) := by
obtain ⟨r, hr⟩ : ∃ (a : O), a * (p : O) = (Quotient.mk'' x).out' - x :=
Ideal.mem_span_singleton'.1 <| Ideal.Quotient.eq.1 <| Quotient.sound' <| Quotient.mk_out' _
refine (if_neg hx).trans (v.map_eq_of_sub_lt <| lt_of_not_le ?_)
erw [← RingHom.map_sub, ← hr, hv.le_iff_dvd]
exact fun hprx =>
hx (Ideal.Quotient.eq_zero_iff_mem.2 <| Ideal.mem_span_singleton.2 <| dvd_of_mul_left_dvd hprx)
#align mod_p.pre_val_mk ModP.preVal_mk
theorem preVal_zero : preVal K v O hv p 0 = 0 :=
if_pos rfl
#align mod_p.pre_val_zero ModP.preVal_zero
| Mathlib/RingTheory/Perfection.lean | 420 | 427 | theorem preVal_mul {x y : ModP K v O hv p} (hxy0 : x * y ≠ 0) :
preVal K v O hv p (x * y) = preVal K v O hv p x * preVal K v O hv p y := by |
have hx0 : x ≠ 0 := mt (by rintro rfl; rw [zero_mul]) hxy0
have hy0 : y ≠ 0 := mt (by rintro rfl; rw [mul_zero]) hxy0
obtain ⟨r, rfl⟩ := Ideal.Quotient.mk_surjective x
obtain ⟨s, rfl⟩ := Ideal.Quotient.mk_surjective y
rw [← map_mul (Ideal.Quotient.mk (Ideal.span {↑p})) r s] at hxy0 ⊢
rw [preVal_mk hx0, preVal_mk hy0, preVal_mk hxy0, RingHom.map_mul, v.map_mul]
| 2,007 |
import Mathlib.Algebra.Algebra.Defs
import Mathlib.Algebra.CharP.ExpChar
import Mathlib.FieldTheory.Separable
#align_import field_theory.separable_degree from "leanprover-community/mathlib"@"d11893b411025250c8e61ff2f12ccbd7ee35ab15"
noncomputable section
namespace Polynomial
open scoped Classical
open Polynomial
section CommSemiring
variable {F : Type*} [CommSemiring F] (q : ℕ)
def IsSeparableContraction (f : F[X]) (g : F[X]) : Prop :=
g.Separable ∧ ∃ m : ℕ, expand F (q ^ m) g = f
#align polynomial.is_separable_contraction Polynomial.IsSeparableContraction
def HasSeparableContraction (f : F[X]) : Prop :=
∃ g : F[X], IsSeparableContraction q f g
#align polynomial.has_separable_contraction Polynomial.HasSeparableContraction
variable {q} {f : F[X]} (hf : HasSeparableContraction q f)
def HasSeparableContraction.contraction : F[X] :=
Classical.choose hf
#align polynomial.has_separable_contraction.contraction Polynomial.HasSeparableContraction.contraction
def HasSeparableContraction.degree : ℕ :=
hf.contraction.natDegree
#align polynomial.has_separable_contraction.degree Polynomial.HasSeparableContraction.degree
theorem HasSeparableContraction.isSeparableContraction :
IsSeparableContraction q f hf.contraction := Classical.choose_spec hf
| Mathlib/RingTheory/Polynomial/SeparableDegree.lean | 78 | 82 | theorem IsSeparableContraction.dvd_degree' {g} (hf : IsSeparableContraction q f g) :
∃ m : ℕ, g.natDegree * q ^ m = f.natDegree := by |
obtain ⟨m, rfl⟩ := hf.2
use m
rw [natDegree_expand]
| 2,008 |
import Mathlib.Algebra.Algebra.Defs
import Mathlib.Algebra.CharP.ExpChar
import Mathlib.FieldTheory.Separable
#align_import field_theory.separable_degree from "leanprover-community/mathlib"@"d11893b411025250c8e61ff2f12ccbd7ee35ab15"
noncomputable section
namespace Polynomial
open scoped Classical
open Polynomial
section CommSemiring
variable {F : Type*} [CommSemiring F] (q : ℕ)
def IsSeparableContraction (f : F[X]) (g : F[X]) : Prop :=
g.Separable ∧ ∃ m : ℕ, expand F (q ^ m) g = f
#align polynomial.is_separable_contraction Polynomial.IsSeparableContraction
def HasSeparableContraction (f : F[X]) : Prop :=
∃ g : F[X], IsSeparableContraction q f g
#align polynomial.has_separable_contraction Polynomial.HasSeparableContraction
variable {q} {f : F[X]} (hf : HasSeparableContraction q f)
def HasSeparableContraction.contraction : F[X] :=
Classical.choose hf
#align polynomial.has_separable_contraction.contraction Polynomial.HasSeparableContraction.contraction
def HasSeparableContraction.degree : ℕ :=
hf.contraction.natDegree
#align polynomial.has_separable_contraction.degree Polynomial.HasSeparableContraction.degree
theorem HasSeparableContraction.isSeparableContraction :
IsSeparableContraction q f hf.contraction := Classical.choose_spec hf
theorem IsSeparableContraction.dvd_degree' {g} (hf : IsSeparableContraction q f g) :
∃ m : ℕ, g.natDegree * q ^ m = f.natDegree := by
obtain ⟨m, rfl⟩ := hf.2
use m
rw [natDegree_expand]
#align polynomial.is_separable_contraction.dvd_degree' Polynomial.IsSeparableContraction.dvd_degree'
theorem HasSeparableContraction.dvd_degree' : ∃ m : ℕ, hf.degree * q ^ m = f.natDegree :=
(Classical.choose_spec hf).dvd_degree' hf
#align polynomial.has_separable_contraction.dvd_degree' Polynomial.HasSeparableContraction.dvd_degree'
theorem HasSeparableContraction.dvd_degree : hf.degree ∣ f.natDegree :=
let ⟨a, ha⟩ := hf.dvd_degree'
Dvd.intro (q ^ a) ha
#align polynomial.has_separable_contraction.dvd_degree Polynomial.HasSeparableContraction.dvd_degree
| Mathlib/RingTheory/Polynomial/SeparableDegree.lean | 96 | 99 | theorem HasSeparableContraction.eq_degree {f : F[X]} (hf : HasSeparableContraction 1 f) :
hf.degree = f.natDegree := by |
let ⟨a, ha⟩ := hf.dvd_degree'
rw [← ha, one_pow a, mul_one]
| 2,008 |
import Mathlib.Algebra.Polynomial.Splits
#align_import algebra.cubic_discriminant from "leanprover-community/mathlib"@"930133160e24036d5242039fe4972407cd4f1222"
noncomputable section
@[ext]
structure Cubic (R : Type*) where
(a b c d : R)
#align cubic Cubic
namespace Cubic
open Cubic Polynomial
open Polynomial
variable {R S F K : Type*}
instance [Inhabited R] : Inhabited (Cubic R) :=
⟨⟨default, default, default, default⟩⟩
instance [Zero R] : Zero (Cubic R) :=
⟨⟨0, 0, 0, 0⟩⟩
section Basic
variable {P Q : Cubic R} {a b c d a' b' c' d' : R} [Semiring R]
def toPoly (P : Cubic R) : R[X] :=
C P.a * X ^ 3 + C P.b * X ^ 2 + C P.c * X + C P.d
#align cubic.to_poly Cubic.toPoly
| Mathlib/Algebra/CubicDiscriminant.lean | 67 | 71 | theorem C_mul_prod_X_sub_C_eq [CommRing S] {w x y z : S} :
C w * (X - C x) * (X - C y) * (X - C z) =
toPoly ⟨w, w * -(x + y + z), w * (x * y + x * z + y * z), w * -(x * y * z)⟩ := by |
simp only [toPoly, C_neg, C_add, C_mul]
ring1
| 2,009 |
import Mathlib.Algebra.Polynomial.Splits
#align_import algebra.cubic_discriminant from "leanprover-community/mathlib"@"930133160e24036d5242039fe4972407cd4f1222"
noncomputable section
@[ext]
structure Cubic (R : Type*) where
(a b c d : R)
#align cubic Cubic
namespace Cubic
open Cubic Polynomial
open Polynomial
variable {R S F K : Type*}
instance [Inhabited R] : Inhabited (Cubic R) :=
⟨⟨default, default, default, default⟩⟩
instance [Zero R] : Zero (Cubic R) :=
⟨⟨0, 0, 0, 0⟩⟩
section Basic
variable {P Q : Cubic R} {a b c d a' b' c' d' : R} [Semiring R]
def toPoly (P : Cubic R) : R[X] :=
C P.a * X ^ 3 + C P.b * X ^ 2 + C P.c * X + C P.d
#align cubic.to_poly Cubic.toPoly
theorem C_mul_prod_X_sub_C_eq [CommRing S] {w x y z : S} :
C w * (X - C x) * (X - C y) * (X - C z) =
toPoly ⟨w, w * -(x + y + z), w * (x * y + x * z + y * z), w * -(x * y * z)⟩ := by
simp only [toPoly, C_neg, C_add, C_mul]
ring1
set_option linter.uppercaseLean3 false in
#align cubic.C_mul_prod_X_sub_C_eq Cubic.C_mul_prod_X_sub_C_eq
| Mathlib/Algebra/CubicDiscriminant.lean | 75 | 78 | theorem prod_X_sub_C_eq [CommRing S] {x y z : S} :
(X - C x) * (X - C y) * (X - C z) =
toPoly ⟨1, -(x + y + z), x * y + x * z + y * z, -(x * y * z)⟩ := by |
rw [← one_mul <| X - C x, ← C_1, C_mul_prod_X_sub_C_eq, one_mul, one_mul, one_mul]
| 2,009 |
import Mathlib.Algebra.Polynomial.Splits
#align_import algebra.cubic_discriminant from "leanprover-community/mathlib"@"930133160e24036d5242039fe4972407cd4f1222"
noncomputable section
@[ext]
structure Cubic (R : Type*) where
(a b c d : R)
#align cubic Cubic
namespace Cubic
open Cubic Polynomial
open Polynomial
variable {R S F K : Type*}
instance [Inhabited R] : Inhabited (Cubic R) :=
⟨⟨default, default, default, default⟩⟩
instance [Zero R] : Zero (Cubic R) :=
⟨⟨0, 0, 0, 0⟩⟩
section Basic
variable {P Q : Cubic R} {a b c d a' b' c' d' : R} [Semiring R]
def toPoly (P : Cubic R) : R[X] :=
C P.a * X ^ 3 + C P.b * X ^ 2 + C P.c * X + C P.d
#align cubic.to_poly Cubic.toPoly
theorem C_mul_prod_X_sub_C_eq [CommRing S] {w x y z : S} :
C w * (X - C x) * (X - C y) * (X - C z) =
toPoly ⟨w, w * -(x + y + z), w * (x * y + x * z + y * z), w * -(x * y * z)⟩ := by
simp only [toPoly, C_neg, C_add, C_mul]
ring1
set_option linter.uppercaseLean3 false in
#align cubic.C_mul_prod_X_sub_C_eq Cubic.C_mul_prod_X_sub_C_eq
theorem prod_X_sub_C_eq [CommRing S] {x y z : S} :
(X - C x) * (X - C y) * (X - C z) =
toPoly ⟨1, -(x + y + z), x * y + x * z + y * z, -(x * y * z)⟩ := by
rw [← one_mul <| X - C x, ← C_1, C_mul_prod_X_sub_C_eq, one_mul, one_mul, one_mul]
set_option linter.uppercaseLean3 false in
#align cubic.prod_X_sub_C_eq Cubic.prod_X_sub_C_eq
section Coeff
private theorem coeffs : (∀ n > 3, P.toPoly.coeff n = 0) ∧ P.toPoly.coeff 3 = P.a ∧
P.toPoly.coeff 2 = P.b ∧ P.toPoly.coeff 1 = P.c ∧ P.toPoly.coeff 0 = P.d := by
simp only [toPoly, coeff_add, coeff_C, coeff_C_mul_X, coeff_C_mul_X_pow]
set_option tactic.skipAssignedInstances false in norm_num
intro n hn
repeat' rw [if_neg]
any_goals linarith only [hn]
repeat' rw [zero_add]
@[simp]
theorem coeff_eq_zero {n : ℕ} (hn : 3 < n) : P.toPoly.coeff n = 0 :=
coeffs.1 n hn
#align cubic.coeff_eq_zero Cubic.coeff_eq_zero
@[simp]
theorem coeff_eq_a : P.toPoly.coeff 3 = P.a :=
coeffs.2.1
#align cubic.coeff_eq_a Cubic.coeff_eq_a
@[simp]
theorem coeff_eq_b : P.toPoly.coeff 2 = P.b :=
coeffs.2.2.1
#align cubic.coeff_eq_b Cubic.coeff_eq_b
@[simp]
theorem coeff_eq_c : P.toPoly.coeff 1 = P.c :=
coeffs.2.2.2.1
#align cubic.coeff_eq_c Cubic.coeff_eq_c
@[simp]
theorem coeff_eq_d : P.toPoly.coeff 0 = P.d :=
coeffs.2.2.2.2
#align cubic.coeff_eq_d Cubic.coeff_eq_d
| Mathlib/Algebra/CubicDiscriminant.lean | 121 | 121 | theorem a_of_eq (h : P.toPoly = Q.toPoly) : P.a = Q.a := by | rw [← coeff_eq_a, h, coeff_eq_a]
| 2,009 |
import Mathlib.Algebra.Polynomial.Splits
#align_import algebra.cubic_discriminant from "leanprover-community/mathlib"@"930133160e24036d5242039fe4972407cd4f1222"
noncomputable section
@[ext]
structure Cubic (R : Type*) where
(a b c d : R)
#align cubic Cubic
namespace Cubic
open Cubic Polynomial
open Polynomial
variable {R S F K : Type*}
instance [Inhabited R] : Inhabited (Cubic R) :=
⟨⟨default, default, default, default⟩⟩
instance [Zero R] : Zero (Cubic R) :=
⟨⟨0, 0, 0, 0⟩⟩
section Basic
variable {P Q : Cubic R} {a b c d a' b' c' d' : R} [Semiring R]
def toPoly (P : Cubic R) : R[X] :=
C P.a * X ^ 3 + C P.b * X ^ 2 + C P.c * X + C P.d
#align cubic.to_poly Cubic.toPoly
theorem C_mul_prod_X_sub_C_eq [CommRing S] {w x y z : S} :
C w * (X - C x) * (X - C y) * (X - C z) =
toPoly ⟨w, w * -(x + y + z), w * (x * y + x * z + y * z), w * -(x * y * z)⟩ := by
simp only [toPoly, C_neg, C_add, C_mul]
ring1
set_option linter.uppercaseLean3 false in
#align cubic.C_mul_prod_X_sub_C_eq Cubic.C_mul_prod_X_sub_C_eq
theorem prod_X_sub_C_eq [CommRing S] {x y z : S} :
(X - C x) * (X - C y) * (X - C z) =
toPoly ⟨1, -(x + y + z), x * y + x * z + y * z, -(x * y * z)⟩ := by
rw [← one_mul <| X - C x, ← C_1, C_mul_prod_X_sub_C_eq, one_mul, one_mul, one_mul]
set_option linter.uppercaseLean3 false in
#align cubic.prod_X_sub_C_eq Cubic.prod_X_sub_C_eq
section Coeff
private theorem coeffs : (∀ n > 3, P.toPoly.coeff n = 0) ∧ P.toPoly.coeff 3 = P.a ∧
P.toPoly.coeff 2 = P.b ∧ P.toPoly.coeff 1 = P.c ∧ P.toPoly.coeff 0 = P.d := by
simp only [toPoly, coeff_add, coeff_C, coeff_C_mul_X, coeff_C_mul_X_pow]
set_option tactic.skipAssignedInstances false in norm_num
intro n hn
repeat' rw [if_neg]
any_goals linarith only [hn]
repeat' rw [zero_add]
@[simp]
theorem coeff_eq_zero {n : ℕ} (hn : 3 < n) : P.toPoly.coeff n = 0 :=
coeffs.1 n hn
#align cubic.coeff_eq_zero Cubic.coeff_eq_zero
@[simp]
theorem coeff_eq_a : P.toPoly.coeff 3 = P.a :=
coeffs.2.1
#align cubic.coeff_eq_a Cubic.coeff_eq_a
@[simp]
theorem coeff_eq_b : P.toPoly.coeff 2 = P.b :=
coeffs.2.2.1
#align cubic.coeff_eq_b Cubic.coeff_eq_b
@[simp]
theorem coeff_eq_c : P.toPoly.coeff 1 = P.c :=
coeffs.2.2.2.1
#align cubic.coeff_eq_c Cubic.coeff_eq_c
@[simp]
theorem coeff_eq_d : P.toPoly.coeff 0 = P.d :=
coeffs.2.2.2.2
#align cubic.coeff_eq_d Cubic.coeff_eq_d
theorem a_of_eq (h : P.toPoly = Q.toPoly) : P.a = Q.a := by rw [← coeff_eq_a, h, coeff_eq_a]
#align cubic.a_of_eq Cubic.a_of_eq
| Mathlib/Algebra/CubicDiscriminant.lean | 124 | 124 | theorem b_of_eq (h : P.toPoly = Q.toPoly) : P.b = Q.b := by | rw [← coeff_eq_b, h, coeff_eq_b]
| 2,009 |
import Mathlib.Algebra.Polynomial.Splits
#align_import algebra.cubic_discriminant from "leanprover-community/mathlib"@"930133160e24036d5242039fe4972407cd4f1222"
noncomputable section
@[ext]
structure Cubic (R : Type*) where
(a b c d : R)
#align cubic Cubic
namespace Cubic
open Cubic Polynomial
open Polynomial
variable {R S F K : Type*}
instance [Inhabited R] : Inhabited (Cubic R) :=
⟨⟨default, default, default, default⟩⟩
instance [Zero R] : Zero (Cubic R) :=
⟨⟨0, 0, 0, 0⟩⟩
section Basic
variable {P Q : Cubic R} {a b c d a' b' c' d' : R} [Semiring R]
def toPoly (P : Cubic R) : R[X] :=
C P.a * X ^ 3 + C P.b * X ^ 2 + C P.c * X + C P.d
#align cubic.to_poly Cubic.toPoly
theorem C_mul_prod_X_sub_C_eq [CommRing S] {w x y z : S} :
C w * (X - C x) * (X - C y) * (X - C z) =
toPoly ⟨w, w * -(x + y + z), w * (x * y + x * z + y * z), w * -(x * y * z)⟩ := by
simp only [toPoly, C_neg, C_add, C_mul]
ring1
set_option linter.uppercaseLean3 false in
#align cubic.C_mul_prod_X_sub_C_eq Cubic.C_mul_prod_X_sub_C_eq
theorem prod_X_sub_C_eq [CommRing S] {x y z : S} :
(X - C x) * (X - C y) * (X - C z) =
toPoly ⟨1, -(x + y + z), x * y + x * z + y * z, -(x * y * z)⟩ := by
rw [← one_mul <| X - C x, ← C_1, C_mul_prod_X_sub_C_eq, one_mul, one_mul, one_mul]
set_option linter.uppercaseLean3 false in
#align cubic.prod_X_sub_C_eq Cubic.prod_X_sub_C_eq
section Coeff
private theorem coeffs : (∀ n > 3, P.toPoly.coeff n = 0) ∧ P.toPoly.coeff 3 = P.a ∧
P.toPoly.coeff 2 = P.b ∧ P.toPoly.coeff 1 = P.c ∧ P.toPoly.coeff 0 = P.d := by
simp only [toPoly, coeff_add, coeff_C, coeff_C_mul_X, coeff_C_mul_X_pow]
set_option tactic.skipAssignedInstances false in norm_num
intro n hn
repeat' rw [if_neg]
any_goals linarith only [hn]
repeat' rw [zero_add]
@[simp]
theorem coeff_eq_zero {n : ℕ} (hn : 3 < n) : P.toPoly.coeff n = 0 :=
coeffs.1 n hn
#align cubic.coeff_eq_zero Cubic.coeff_eq_zero
@[simp]
theorem coeff_eq_a : P.toPoly.coeff 3 = P.a :=
coeffs.2.1
#align cubic.coeff_eq_a Cubic.coeff_eq_a
@[simp]
theorem coeff_eq_b : P.toPoly.coeff 2 = P.b :=
coeffs.2.2.1
#align cubic.coeff_eq_b Cubic.coeff_eq_b
@[simp]
theorem coeff_eq_c : P.toPoly.coeff 1 = P.c :=
coeffs.2.2.2.1
#align cubic.coeff_eq_c Cubic.coeff_eq_c
@[simp]
theorem coeff_eq_d : P.toPoly.coeff 0 = P.d :=
coeffs.2.2.2.2
#align cubic.coeff_eq_d Cubic.coeff_eq_d
theorem a_of_eq (h : P.toPoly = Q.toPoly) : P.a = Q.a := by rw [← coeff_eq_a, h, coeff_eq_a]
#align cubic.a_of_eq Cubic.a_of_eq
theorem b_of_eq (h : P.toPoly = Q.toPoly) : P.b = Q.b := by rw [← coeff_eq_b, h, coeff_eq_b]
#align cubic.b_of_eq Cubic.b_of_eq
| Mathlib/Algebra/CubicDiscriminant.lean | 127 | 127 | theorem c_of_eq (h : P.toPoly = Q.toPoly) : P.c = Q.c := by | rw [← coeff_eq_c, h, coeff_eq_c]
| 2,009 |
import Mathlib.Algebra.Polynomial.Splits
#align_import algebra.cubic_discriminant from "leanprover-community/mathlib"@"930133160e24036d5242039fe4972407cd4f1222"
noncomputable section
@[ext]
structure Cubic (R : Type*) where
(a b c d : R)
#align cubic Cubic
namespace Cubic
open Cubic Polynomial
open Polynomial
variable {R S F K : Type*}
instance [Inhabited R] : Inhabited (Cubic R) :=
⟨⟨default, default, default, default⟩⟩
instance [Zero R] : Zero (Cubic R) :=
⟨⟨0, 0, 0, 0⟩⟩
section Basic
variable {P Q : Cubic R} {a b c d a' b' c' d' : R} [Semiring R]
def toPoly (P : Cubic R) : R[X] :=
C P.a * X ^ 3 + C P.b * X ^ 2 + C P.c * X + C P.d
#align cubic.to_poly Cubic.toPoly
theorem C_mul_prod_X_sub_C_eq [CommRing S] {w x y z : S} :
C w * (X - C x) * (X - C y) * (X - C z) =
toPoly ⟨w, w * -(x + y + z), w * (x * y + x * z + y * z), w * -(x * y * z)⟩ := by
simp only [toPoly, C_neg, C_add, C_mul]
ring1
set_option linter.uppercaseLean3 false in
#align cubic.C_mul_prod_X_sub_C_eq Cubic.C_mul_prod_X_sub_C_eq
theorem prod_X_sub_C_eq [CommRing S] {x y z : S} :
(X - C x) * (X - C y) * (X - C z) =
toPoly ⟨1, -(x + y + z), x * y + x * z + y * z, -(x * y * z)⟩ := by
rw [← one_mul <| X - C x, ← C_1, C_mul_prod_X_sub_C_eq, one_mul, one_mul, one_mul]
set_option linter.uppercaseLean3 false in
#align cubic.prod_X_sub_C_eq Cubic.prod_X_sub_C_eq
section Coeff
private theorem coeffs : (∀ n > 3, P.toPoly.coeff n = 0) ∧ P.toPoly.coeff 3 = P.a ∧
P.toPoly.coeff 2 = P.b ∧ P.toPoly.coeff 1 = P.c ∧ P.toPoly.coeff 0 = P.d := by
simp only [toPoly, coeff_add, coeff_C, coeff_C_mul_X, coeff_C_mul_X_pow]
set_option tactic.skipAssignedInstances false in norm_num
intro n hn
repeat' rw [if_neg]
any_goals linarith only [hn]
repeat' rw [zero_add]
@[simp]
theorem coeff_eq_zero {n : ℕ} (hn : 3 < n) : P.toPoly.coeff n = 0 :=
coeffs.1 n hn
#align cubic.coeff_eq_zero Cubic.coeff_eq_zero
@[simp]
theorem coeff_eq_a : P.toPoly.coeff 3 = P.a :=
coeffs.2.1
#align cubic.coeff_eq_a Cubic.coeff_eq_a
@[simp]
theorem coeff_eq_b : P.toPoly.coeff 2 = P.b :=
coeffs.2.2.1
#align cubic.coeff_eq_b Cubic.coeff_eq_b
@[simp]
theorem coeff_eq_c : P.toPoly.coeff 1 = P.c :=
coeffs.2.2.2.1
#align cubic.coeff_eq_c Cubic.coeff_eq_c
@[simp]
theorem coeff_eq_d : P.toPoly.coeff 0 = P.d :=
coeffs.2.2.2.2
#align cubic.coeff_eq_d Cubic.coeff_eq_d
theorem a_of_eq (h : P.toPoly = Q.toPoly) : P.a = Q.a := by rw [← coeff_eq_a, h, coeff_eq_a]
#align cubic.a_of_eq Cubic.a_of_eq
theorem b_of_eq (h : P.toPoly = Q.toPoly) : P.b = Q.b := by rw [← coeff_eq_b, h, coeff_eq_b]
#align cubic.b_of_eq Cubic.b_of_eq
theorem c_of_eq (h : P.toPoly = Q.toPoly) : P.c = Q.c := by rw [← coeff_eq_c, h, coeff_eq_c]
#align cubic.c_of_eq Cubic.c_of_eq
| Mathlib/Algebra/CubicDiscriminant.lean | 130 | 130 | theorem d_of_eq (h : P.toPoly = Q.toPoly) : P.d = Q.d := by | rw [← coeff_eq_d, h, coeff_eq_d]
| 2,009 |
import Mathlib.Algebra.Polynomial.Splits
#align_import algebra.cubic_discriminant from "leanprover-community/mathlib"@"930133160e24036d5242039fe4972407cd4f1222"
noncomputable section
@[ext]
structure Cubic (R : Type*) where
(a b c d : R)
#align cubic Cubic
namespace Cubic
open Cubic Polynomial
open Polynomial
variable {R S F K : Type*}
instance [Inhabited R] : Inhabited (Cubic R) :=
⟨⟨default, default, default, default⟩⟩
instance [Zero R] : Zero (Cubic R) :=
⟨⟨0, 0, 0, 0⟩⟩
section Basic
variable {P Q : Cubic R} {a b c d a' b' c' d' : R} [Semiring R]
def toPoly (P : Cubic R) : R[X] :=
C P.a * X ^ 3 + C P.b * X ^ 2 + C P.c * X + C P.d
#align cubic.to_poly Cubic.toPoly
theorem C_mul_prod_X_sub_C_eq [CommRing S] {w x y z : S} :
C w * (X - C x) * (X - C y) * (X - C z) =
toPoly ⟨w, w * -(x + y + z), w * (x * y + x * z + y * z), w * -(x * y * z)⟩ := by
simp only [toPoly, C_neg, C_add, C_mul]
ring1
set_option linter.uppercaseLean3 false in
#align cubic.C_mul_prod_X_sub_C_eq Cubic.C_mul_prod_X_sub_C_eq
theorem prod_X_sub_C_eq [CommRing S] {x y z : S} :
(X - C x) * (X - C y) * (X - C z) =
toPoly ⟨1, -(x + y + z), x * y + x * z + y * z, -(x * y * z)⟩ := by
rw [← one_mul <| X - C x, ← C_1, C_mul_prod_X_sub_C_eq, one_mul, one_mul, one_mul]
set_option linter.uppercaseLean3 false in
#align cubic.prod_X_sub_C_eq Cubic.prod_X_sub_C_eq
section Coeff
private theorem coeffs : (∀ n > 3, P.toPoly.coeff n = 0) ∧ P.toPoly.coeff 3 = P.a ∧
P.toPoly.coeff 2 = P.b ∧ P.toPoly.coeff 1 = P.c ∧ P.toPoly.coeff 0 = P.d := by
simp only [toPoly, coeff_add, coeff_C, coeff_C_mul_X, coeff_C_mul_X_pow]
set_option tactic.skipAssignedInstances false in norm_num
intro n hn
repeat' rw [if_neg]
any_goals linarith only [hn]
repeat' rw [zero_add]
@[simp]
theorem coeff_eq_zero {n : ℕ} (hn : 3 < n) : P.toPoly.coeff n = 0 :=
coeffs.1 n hn
#align cubic.coeff_eq_zero Cubic.coeff_eq_zero
@[simp]
theorem coeff_eq_a : P.toPoly.coeff 3 = P.a :=
coeffs.2.1
#align cubic.coeff_eq_a Cubic.coeff_eq_a
@[simp]
theorem coeff_eq_b : P.toPoly.coeff 2 = P.b :=
coeffs.2.2.1
#align cubic.coeff_eq_b Cubic.coeff_eq_b
@[simp]
theorem coeff_eq_c : P.toPoly.coeff 1 = P.c :=
coeffs.2.2.2.1
#align cubic.coeff_eq_c Cubic.coeff_eq_c
@[simp]
theorem coeff_eq_d : P.toPoly.coeff 0 = P.d :=
coeffs.2.2.2.2
#align cubic.coeff_eq_d Cubic.coeff_eq_d
theorem a_of_eq (h : P.toPoly = Q.toPoly) : P.a = Q.a := by rw [← coeff_eq_a, h, coeff_eq_a]
#align cubic.a_of_eq Cubic.a_of_eq
theorem b_of_eq (h : P.toPoly = Q.toPoly) : P.b = Q.b := by rw [← coeff_eq_b, h, coeff_eq_b]
#align cubic.b_of_eq Cubic.b_of_eq
theorem c_of_eq (h : P.toPoly = Q.toPoly) : P.c = Q.c := by rw [← coeff_eq_c, h, coeff_eq_c]
#align cubic.c_of_eq Cubic.c_of_eq
theorem d_of_eq (h : P.toPoly = Q.toPoly) : P.d = Q.d := by rw [← coeff_eq_d, h, coeff_eq_d]
#align cubic.d_of_eq Cubic.d_of_eq
theorem toPoly_injective (P Q : Cubic R) : P.toPoly = Q.toPoly ↔ P = Q :=
⟨fun h ↦ Cubic.ext P Q (a_of_eq h) (b_of_eq h) (c_of_eq h) (d_of_eq h), congr_arg toPoly⟩
#align cubic.to_poly_injective Cubic.toPoly_injective
| Mathlib/Algebra/CubicDiscriminant.lean | 137 | 138 | theorem of_a_eq_zero (ha : P.a = 0) : P.toPoly = C P.b * X ^ 2 + C P.c * X + C P.d := by |
rw [toPoly, ha, C_0, zero_mul, zero_add]
| 2,009 |
import Mathlib.Algebra.Polynomial.Splits
#align_import algebra.cubic_discriminant from "leanprover-community/mathlib"@"930133160e24036d5242039fe4972407cd4f1222"
noncomputable section
@[ext]
structure Cubic (R : Type*) where
(a b c d : R)
#align cubic Cubic
namespace Cubic
open Cubic Polynomial
open Polynomial
variable {R S F K : Type*}
instance [Inhabited R] : Inhabited (Cubic R) :=
⟨⟨default, default, default, default⟩⟩
instance [Zero R] : Zero (Cubic R) :=
⟨⟨0, 0, 0, 0⟩⟩
section Basic
variable {P Q : Cubic R} {a b c d a' b' c' d' : R} [Semiring R]
def toPoly (P : Cubic R) : R[X] :=
C P.a * X ^ 3 + C P.b * X ^ 2 + C P.c * X + C P.d
#align cubic.to_poly Cubic.toPoly
theorem C_mul_prod_X_sub_C_eq [CommRing S] {w x y z : S} :
C w * (X - C x) * (X - C y) * (X - C z) =
toPoly ⟨w, w * -(x + y + z), w * (x * y + x * z + y * z), w * -(x * y * z)⟩ := by
simp only [toPoly, C_neg, C_add, C_mul]
ring1
set_option linter.uppercaseLean3 false in
#align cubic.C_mul_prod_X_sub_C_eq Cubic.C_mul_prod_X_sub_C_eq
theorem prod_X_sub_C_eq [CommRing S] {x y z : S} :
(X - C x) * (X - C y) * (X - C z) =
toPoly ⟨1, -(x + y + z), x * y + x * z + y * z, -(x * y * z)⟩ := by
rw [← one_mul <| X - C x, ← C_1, C_mul_prod_X_sub_C_eq, one_mul, one_mul, one_mul]
set_option linter.uppercaseLean3 false in
#align cubic.prod_X_sub_C_eq Cubic.prod_X_sub_C_eq
section Coeff
private theorem coeffs : (∀ n > 3, P.toPoly.coeff n = 0) ∧ P.toPoly.coeff 3 = P.a ∧
P.toPoly.coeff 2 = P.b ∧ P.toPoly.coeff 1 = P.c ∧ P.toPoly.coeff 0 = P.d := by
simp only [toPoly, coeff_add, coeff_C, coeff_C_mul_X, coeff_C_mul_X_pow]
set_option tactic.skipAssignedInstances false in norm_num
intro n hn
repeat' rw [if_neg]
any_goals linarith only [hn]
repeat' rw [zero_add]
@[simp]
theorem coeff_eq_zero {n : ℕ} (hn : 3 < n) : P.toPoly.coeff n = 0 :=
coeffs.1 n hn
#align cubic.coeff_eq_zero Cubic.coeff_eq_zero
@[simp]
theorem coeff_eq_a : P.toPoly.coeff 3 = P.a :=
coeffs.2.1
#align cubic.coeff_eq_a Cubic.coeff_eq_a
@[simp]
theorem coeff_eq_b : P.toPoly.coeff 2 = P.b :=
coeffs.2.2.1
#align cubic.coeff_eq_b Cubic.coeff_eq_b
@[simp]
theorem coeff_eq_c : P.toPoly.coeff 1 = P.c :=
coeffs.2.2.2.1
#align cubic.coeff_eq_c Cubic.coeff_eq_c
@[simp]
theorem coeff_eq_d : P.toPoly.coeff 0 = P.d :=
coeffs.2.2.2.2
#align cubic.coeff_eq_d Cubic.coeff_eq_d
theorem a_of_eq (h : P.toPoly = Q.toPoly) : P.a = Q.a := by rw [← coeff_eq_a, h, coeff_eq_a]
#align cubic.a_of_eq Cubic.a_of_eq
theorem b_of_eq (h : P.toPoly = Q.toPoly) : P.b = Q.b := by rw [← coeff_eq_b, h, coeff_eq_b]
#align cubic.b_of_eq Cubic.b_of_eq
theorem c_of_eq (h : P.toPoly = Q.toPoly) : P.c = Q.c := by rw [← coeff_eq_c, h, coeff_eq_c]
#align cubic.c_of_eq Cubic.c_of_eq
theorem d_of_eq (h : P.toPoly = Q.toPoly) : P.d = Q.d := by rw [← coeff_eq_d, h, coeff_eq_d]
#align cubic.d_of_eq Cubic.d_of_eq
theorem toPoly_injective (P Q : Cubic R) : P.toPoly = Q.toPoly ↔ P = Q :=
⟨fun h ↦ Cubic.ext P Q (a_of_eq h) (b_of_eq h) (c_of_eq h) (d_of_eq h), congr_arg toPoly⟩
#align cubic.to_poly_injective Cubic.toPoly_injective
theorem of_a_eq_zero (ha : P.a = 0) : P.toPoly = C P.b * X ^ 2 + C P.c * X + C P.d := by
rw [toPoly, ha, C_0, zero_mul, zero_add]
#align cubic.of_a_eq_zero Cubic.of_a_eq_zero
theorem of_a_eq_zero' : toPoly ⟨0, b, c, d⟩ = C b * X ^ 2 + C c * X + C d :=
of_a_eq_zero rfl
#align cubic.of_a_eq_zero' Cubic.of_a_eq_zero'
| Mathlib/Algebra/CubicDiscriminant.lean | 145 | 146 | theorem of_b_eq_zero (ha : P.a = 0) (hb : P.b = 0) : P.toPoly = C P.c * X + C P.d := by |
rw [of_a_eq_zero ha, hb, C_0, zero_mul, zero_add]
| 2,009 |
import Mathlib.Algebra.Polynomial.Splits
#align_import algebra.cubic_discriminant from "leanprover-community/mathlib"@"930133160e24036d5242039fe4972407cd4f1222"
noncomputable section
@[ext]
structure Cubic (R : Type*) where
(a b c d : R)
#align cubic Cubic
namespace Cubic
open Cubic Polynomial
open Polynomial
variable {R S F K : Type*}
instance [Inhabited R] : Inhabited (Cubic R) :=
⟨⟨default, default, default, default⟩⟩
instance [Zero R] : Zero (Cubic R) :=
⟨⟨0, 0, 0, 0⟩⟩
section Basic
variable {P Q : Cubic R} {a b c d a' b' c' d' : R} [Semiring R]
def toPoly (P : Cubic R) : R[X] :=
C P.a * X ^ 3 + C P.b * X ^ 2 + C P.c * X + C P.d
#align cubic.to_poly Cubic.toPoly
theorem C_mul_prod_X_sub_C_eq [CommRing S] {w x y z : S} :
C w * (X - C x) * (X - C y) * (X - C z) =
toPoly ⟨w, w * -(x + y + z), w * (x * y + x * z + y * z), w * -(x * y * z)⟩ := by
simp only [toPoly, C_neg, C_add, C_mul]
ring1
set_option linter.uppercaseLean3 false in
#align cubic.C_mul_prod_X_sub_C_eq Cubic.C_mul_prod_X_sub_C_eq
theorem prod_X_sub_C_eq [CommRing S] {x y z : S} :
(X - C x) * (X - C y) * (X - C z) =
toPoly ⟨1, -(x + y + z), x * y + x * z + y * z, -(x * y * z)⟩ := by
rw [← one_mul <| X - C x, ← C_1, C_mul_prod_X_sub_C_eq, one_mul, one_mul, one_mul]
set_option linter.uppercaseLean3 false in
#align cubic.prod_X_sub_C_eq Cubic.prod_X_sub_C_eq
section Coeff
private theorem coeffs : (∀ n > 3, P.toPoly.coeff n = 0) ∧ P.toPoly.coeff 3 = P.a ∧
P.toPoly.coeff 2 = P.b ∧ P.toPoly.coeff 1 = P.c ∧ P.toPoly.coeff 0 = P.d := by
simp only [toPoly, coeff_add, coeff_C, coeff_C_mul_X, coeff_C_mul_X_pow]
set_option tactic.skipAssignedInstances false in norm_num
intro n hn
repeat' rw [if_neg]
any_goals linarith only [hn]
repeat' rw [zero_add]
@[simp]
theorem coeff_eq_zero {n : ℕ} (hn : 3 < n) : P.toPoly.coeff n = 0 :=
coeffs.1 n hn
#align cubic.coeff_eq_zero Cubic.coeff_eq_zero
@[simp]
theorem coeff_eq_a : P.toPoly.coeff 3 = P.a :=
coeffs.2.1
#align cubic.coeff_eq_a Cubic.coeff_eq_a
@[simp]
theorem coeff_eq_b : P.toPoly.coeff 2 = P.b :=
coeffs.2.2.1
#align cubic.coeff_eq_b Cubic.coeff_eq_b
@[simp]
theorem coeff_eq_c : P.toPoly.coeff 1 = P.c :=
coeffs.2.2.2.1
#align cubic.coeff_eq_c Cubic.coeff_eq_c
@[simp]
theorem coeff_eq_d : P.toPoly.coeff 0 = P.d :=
coeffs.2.2.2.2
#align cubic.coeff_eq_d Cubic.coeff_eq_d
theorem a_of_eq (h : P.toPoly = Q.toPoly) : P.a = Q.a := by rw [← coeff_eq_a, h, coeff_eq_a]
#align cubic.a_of_eq Cubic.a_of_eq
theorem b_of_eq (h : P.toPoly = Q.toPoly) : P.b = Q.b := by rw [← coeff_eq_b, h, coeff_eq_b]
#align cubic.b_of_eq Cubic.b_of_eq
theorem c_of_eq (h : P.toPoly = Q.toPoly) : P.c = Q.c := by rw [← coeff_eq_c, h, coeff_eq_c]
#align cubic.c_of_eq Cubic.c_of_eq
theorem d_of_eq (h : P.toPoly = Q.toPoly) : P.d = Q.d := by rw [← coeff_eq_d, h, coeff_eq_d]
#align cubic.d_of_eq Cubic.d_of_eq
theorem toPoly_injective (P Q : Cubic R) : P.toPoly = Q.toPoly ↔ P = Q :=
⟨fun h ↦ Cubic.ext P Q (a_of_eq h) (b_of_eq h) (c_of_eq h) (d_of_eq h), congr_arg toPoly⟩
#align cubic.to_poly_injective Cubic.toPoly_injective
theorem of_a_eq_zero (ha : P.a = 0) : P.toPoly = C P.b * X ^ 2 + C P.c * X + C P.d := by
rw [toPoly, ha, C_0, zero_mul, zero_add]
#align cubic.of_a_eq_zero Cubic.of_a_eq_zero
theorem of_a_eq_zero' : toPoly ⟨0, b, c, d⟩ = C b * X ^ 2 + C c * X + C d :=
of_a_eq_zero rfl
#align cubic.of_a_eq_zero' Cubic.of_a_eq_zero'
theorem of_b_eq_zero (ha : P.a = 0) (hb : P.b = 0) : P.toPoly = C P.c * X + C P.d := by
rw [of_a_eq_zero ha, hb, C_0, zero_mul, zero_add]
#align cubic.of_b_eq_zero Cubic.of_b_eq_zero
theorem of_b_eq_zero' : toPoly ⟨0, 0, c, d⟩ = C c * X + C d :=
of_b_eq_zero rfl rfl
#align cubic.of_b_eq_zero' Cubic.of_b_eq_zero'
| Mathlib/Algebra/CubicDiscriminant.lean | 153 | 154 | theorem of_c_eq_zero (ha : P.a = 0) (hb : P.b = 0) (hc : P.c = 0) : P.toPoly = C P.d := by |
rw [of_b_eq_zero ha hb, hc, C_0, zero_mul, zero_add]
| 2,009 |
import Mathlib.Algebra.Polynomial.Splits
#align_import algebra.cubic_discriminant from "leanprover-community/mathlib"@"930133160e24036d5242039fe4972407cd4f1222"
noncomputable section
@[ext]
structure Cubic (R : Type*) where
(a b c d : R)
#align cubic Cubic
namespace Cubic
open Cubic Polynomial
open Polynomial
variable {R S F K : Type*}
instance [Inhabited R] : Inhabited (Cubic R) :=
⟨⟨default, default, default, default⟩⟩
instance [Zero R] : Zero (Cubic R) :=
⟨⟨0, 0, 0, 0⟩⟩
section Basic
variable {P Q : Cubic R} {a b c d a' b' c' d' : R} [Semiring R]
def toPoly (P : Cubic R) : R[X] :=
C P.a * X ^ 3 + C P.b * X ^ 2 + C P.c * X + C P.d
#align cubic.to_poly Cubic.toPoly
theorem C_mul_prod_X_sub_C_eq [CommRing S] {w x y z : S} :
C w * (X - C x) * (X - C y) * (X - C z) =
toPoly ⟨w, w * -(x + y + z), w * (x * y + x * z + y * z), w * -(x * y * z)⟩ := by
simp only [toPoly, C_neg, C_add, C_mul]
ring1
set_option linter.uppercaseLean3 false in
#align cubic.C_mul_prod_X_sub_C_eq Cubic.C_mul_prod_X_sub_C_eq
theorem prod_X_sub_C_eq [CommRing S] {x y z : S} :
(X - C x) * (X - C y) * (X - C z) =
toPoly ⟨1, -(x + y + z), x * y + x * z + y * z, -(x * y * z)⟩ := by
rw [← one_mul <| X - C x, ← C_1, C_mul_prod_X_sub_C_eq, one_mul, one_mul, one_mul]
set_option linter.uppercaseLean3 false in
#align cubic.prod_X_sub_C_eq Cubic.prod_X_sub_C_eq
section Map
variable [Semiring S] {φ : R →+* S}
def map (φ : R →+* S) (P : Cubic R) : Cubic S :=
⟨φ P.a, φ P.b, φ P.c, φ P.d⟩
#align cubic.map Cubic.map
| Mathlib/Algebra/CubicDiscriminant.lean | 458 | 459 | theorem map_toPoly : (map φ P).toPoly = Polynomial.map φ P.toPoly := by |
simp only [map, toPoly, map_C, map_X, Polynomial.map_add, Polynomial.map_mul, Polynomial.map_pow]
| 2,009 |
import Mathlib.Algebra.Polynomial.Splits
import Mathlib.RingTheory.MvPolynomial.Symmetric
#align_import ring_theory.polynomial.vieta from "leanprover-community/mathlib"@"f694c7dead66f5d4c80f446c796a5aad14707f0e"
open Polynomial
namespace Multiset
open Polynomial
section Semiring
variable {R : Type*} [CommSemiring R]
| Mathlib/RingTheory/Polynomial/Vieta.lean | 41 | 53 | theorem prod_X_add_C_eq_sum_esymm (s : Multiset R) :
(s.map fun r => X + C r).prod =
∑ j ∈ Finset.range (Multiset.card s + 1), (C (s.esymm j) * X ^ (Multiset.card s - j)) := by |
classical
rw [prod_map_add, antidiagonal_eq_map_powerset, map_map, ← bind_powerset_len,
map_bind, sum_bind, Finset.sum_eq_multiset_sum, Finset.range_val, map_congr (Eq.refl _)]
intro _ _
rw [esymm, ← sum_hom', ← sum_map_mul_right, map_congr (Eq.refl _)]
intro s ht
rw [mem_powersetCard] at ht
dsimp
rw [prod_hom' s (Polynomial.C : R →+* R[X])]
simp [ht, map_const, prod_replicate, prod_hom', map_id', card_sub]
| 2,010 |
import Mathlib.Algebra.Polynomial.Splits
import Mathlib.RingTheory.MvPolynomial.Symmetric
#align_import ring_theory.polynomial.vieta from "leanprover-community/mathlib"@"f694c7dead66f5d4c80f446c796a5aad14707f0e"
open Polynomial
namespace Multiset
open Polynomial
section Semiring
variable {R : Type*} [CommSemiring R]
theorem prod_X_add_C_eq_sum_esymm (s : Multiset R) :
(s.map fun r => X + C r).prod =
∑ j ∈ Finset.range (Multiset.card s + 1), (C (s.esymm j) * X ^ (Multiset.card s - j)) := by
classical
rw [prod_map_add, antidiagonal_eq_map_powerset, map_map, ← bind_powerset_len,
map_bind, sum_bind, Finset.sum_eq_multiset_sum, Finset.range_val, map_congr (Eq.refl _)]
intro _ _
rw [esymm, ← sum_hom', ← sum_map_mul_right, map_congr (Eq.refl _)]
intro s ht
rw [mem_powersetCard] at ht
dsimp
rw [prod_hom' s (Polynomial.C : R →+* R[X])]
simp [ht, map_const, prod_replicate, prod_hom', map_id', card_sub]
set_option linter.uppercaseLean3 false in
#align multiset.prod_X_add_C_eq_sum_esymm Multiset.prod_X_add_C_eq_sum_esymm
| Mathlib/RingTheory/Polynomial/Vieta.lean | 59 | 71 | theorem prod_X_add_C_coeff (s : Multiset R) {k : ℕ} (h : k ≤ Multiset.card s) :
(s.map fun r => X + C r).prod.coeff k = s.esymm (Multiset.card s - k) := by |
convert Polynomial.ext_iff.mp (prod_X_add_C_eq_sum_esymm s) k using 1
simp_rw [finset_sum_coeff, coeff_C_mul_X_pow]
rw [Finset.sum_eq_single_of_mem (Multiset.card s - k) _]
· rw [if_pos (Nat.sub_sub_self h).symm]
· intro j hj1 hj2
suffices k ≠ card s - j by rw [if_neg this]
intro hn
rw [hn, Nat.sub_sub_self (Nat.lt_succ_iff.mp (Finset.mem_range.mp hj1))] at hj2
exact Ne.irrefl hj2
· rw [Finset.mem_range]
exact Nat.lt_succ_of_le (Nat.sub_le (Multiset.card s) k)
| 2,010 |
import Mathlib.Algebra.Polynomial.Splits
import Mathlib.RingTheory.MvPolynomial.Symmetric
#align_import ring_theory.polynomial.vieta from "leanprover-community/mathlib"@"f694c7dead66f5d4c80f446c796a5aad14707f0e"
open Polynomial
namespace Multiset
open Polynomial
section Semiring
variable {R : Type*} [CommSemiring R]
theorem prod_X_add_C_eq_sum_esymm (s : Multiset R) :
(s.map fun r => X + C r).prod =
∑ j ∈ Finset.range (Multiset.card s + 1), (C (s.esymm j) * X ^ (Multiset.card s - j)) := by
classical
rw [prod_map_add, antidiagonal_eq_map_powerset, map_map, ← bind_powerset_len,
map_bind, sum_bind, Finset.sum_eq_multiset_sum, Finset.range_val, map_congr (Eq.refl _)]
intro _ _
rw [esymm, ← sum_hom', ← sum_map_mul_right, map_congr (Eq.refl _)]
intro s ht
rw [mem_powersetCard] at ht
dsimp
rw [prod_hom' s (Polynomial.C : R →+* R[X])]
simp [ht, map_const, prod_replicate, prod_hom', map_id', card_sub]
set_option linter.uppercaseLean3 false in
#align multiset.prod_X_add_C_eq_sum_esymm Multiset.prod_X_add_C_eq_sum_esymm
theorem prod_X_add_C_coeff (s : Multiset R) {k : ℕ} (h : k ≤ Multiset.card s) :
(s.map fun r => X + C r).prod.coeff k = s.esymm (Multiset.card s - k) := by
convert Polynomial.ext_iff.mp (prod_X_add_C_eq_sum_esymm s) k using 1
simp_rw [finset_sum_coeff, coeff_C_mul_X_pow]
rw [Finset.sum_eq_single_of_mem (Multiset.card s - k) _]
· rw [if_pos (Nat.sub_sub_self h).symm]
· intro j hj1 hj2
suffices k ≠ card s - j by rw [if_neg this]
intro hn
rw [hn, Nat.sub_sub_self (Nat.lt_succ_iff.mp (Finset.mem_range.mp hj1))] at hj2
exact Ne.irrefl hj2
· rw [Finset.mem_range]
exact Nat.lt_succ_of_le (Nat.sub_le (Multiset.card s) k)
set_option linter.uppercaseLean3 false in
#align multiset.prod_X_add_C_coeff Multiset.prod_X_add_C_coeff
| Mathlib/RingTheory/Polynomial/Vieta.lean | 75 | 77 | theorem prod_X_add_C_coeff' {σ} (s : Multiset σ) (r : σ → R) {k : ℕ} (h : k ≤ Multiset.card s) :
(s.map fun i => X + C (r i)).prod.coeff k = (s.map r).esymm (Multiset.card s - k) := by |
erw [← map_map (fun r => X + C r) r, prod_X_add_C_coeff] <;> rw [s.card_map r]; assumption
| 2,010 |
import Mathlib.Algebra.Polynomial.Splits
import Mathlib.RingTheory.MvPolynomial.Symmetric
#align_import ring_theory.polynomial.vieta from "leanprover-community/mathlib"@"f694c7dead66f5d4c80f446c796a5aad14707f0e"
open Polynomial
namespace Multiset
open Polynomial
section Semiring
variable {R : Type*} [CommSemiring R]
theorem prod_X_add_C_eq_sum_esymm (s : Multiset R) :
(s.map fun r => X + C r).prod =
∑ j ∈ Finset.range (Multiset.card s + 1), (C (s.esymm j) * X ^ (Multiset.card s - j)) := by
classical
rw [prod_map_add, antidiagonal_eq_map_powerset, map_map, ← bind_powerset_len,
map_bind, sum_bind, Finset.sum_eq_multiset_sum, Finset.range_val, map_congr (Eq.refl _)]
intro _ _
rw [esymm, ← sum_hom', ← sum_map_mul_right, map_congr (Eq.refl _)]
intro s ht
rw [mem_powersetCard] at ht
dsimp
rw [prod_hom' s (Polynomial.C : R →+* R[X])]
simp [ht, map_const, prod_replicate, prod_hom', map_id', card_sub]
set_option linter.uppercaseLean3 false in
#align multiset.prod_X_add_C_eq_sum_esymm Multiset.prod_X_add_C_eq_sum_esymm
theorem prod_X_add_C_coeff (s : Multiset R) {k : ℕ} (h : k ≤ Multiset.card s) :
(s.map fun r => X + C r).prod.coeff k = s.esymm (Multiset.card s - k) := by
convert Polynomial.ext_iff.mp (prod_X_add_C_eq_sum_esymm s) k using 1
simp_rw [finset_sum_coeff, coeff_C_mul_X_pow]
rw [Finset.sum_eq_single_of_mem (Multiset.card s - k) _]
· rw [if_pos (Nat.sub_sub_self h).symm]
· intro j hj1 hj2
suffices k ≠ card s - j by rw [if_neg this]
intro hn
rw [hn, Nat.sub_sub_self (Nat.lt_succ_iff.mp (Finset.mem_range.mp hj1))] at hj2
exact Ne.irrefl hj2
· rw [Finset.mem_range]
exact Nat.lt_succ_of_le (Nat.sub_le (Multiset.card s) k)
set_option linter.uppercaseLean3 false in
#align multiset.prod_X_add_C_coeff Multiset.prod_X_add_C_coeff
theorem prod_X_add_C_coeff' {σ} (s : Multiset σ) (r : σ → R) {k : ℕ} (h : k ≤ Multiset.card s) :
(s.map fun i => X + C (r i)).prod.coeff k = (s.map r).esymm (Multiset.card s - k) := by
erw [← map_map (fun r => X + C r) r, prod_X_add_C_coeff] <;> rw [s.card_map r]; assumption
set_option linter.uppercaseLean3 false in
#align multiset.prod_X_add_C_coeff' Multiset.prod_X_add_C_coeff'
| Mathlib/RingTheory/Polynomial/Vieta.lean | 81 | 84 | theorem _root_.Finset.prod_X_add_C_coeff {σ} (s : Finset σ) (r : σ → R) {k : ℕ} (h : k ≤ s.card) :
(∏ i ∈ s, (X + C (r i))).coeff k = ∑ t ∈ s.powersetCard (s.card - k), ∏ i ∈ t, r i := by |
rw [Finset.prod, prod_X_add_C_coeff' _ r h, Finset.esymm_map_val]
rfl
| 2,010 |
import Mathlib.Algebra.Polynomial.Splits
import Mathlib.RingTheory.MvPolynomial.Symmetric
#align_import ring_theory.polynomial.vieta from "leanprover-community/mathlib"@"f694c7dead66f5d4c80f446c796a5aad14707f0e"
open Polynomial
namespace Multiset
open Polynomial
section Ring
variable {R : Type*} [CommRing R]
| Mathlib/RingTheory/Polynomial/Vieta.lean | 94 | 101 | theorem esymm_neg (s : Multiset R) (k : ℕ) : (map Neg.neg s).esymm k = (-1) ^ k * esymm s k := by |
rw [esymm, esymm, ← Multiset.sum_map_mul_left, Multiset.powersetCard_map, Multiset.map_map,
map_congr rfl]
intro x hx
rw [(mem_powersetCard.mp hx).right.symm, ← prod_replicate, ← Multiset.map_const]
nth_rw 3 [← map_id' x]
rw [← prod_map_mul, map_congr rfl, Function.comp_apply]
exact fun z _ => neg_one_mul z
| 2,010 |
import Mathlib.Algebra.Polynomial.AlgebraMap
import Mathlib.Algebra.Polynomial.Inductions
import Mathlib.Algebra.Polynomial.Splits
import Mathlib.Analysis.Normed.Field.Basic
import Mathlib.RingTheory.Polynomial.Vieta
#align_import topology.algebra.polynomial from "leanprover-community/mathlib"@"565eb991e264d0db702722b4bde52ee5173c9950"
open IsAbsoluteValue Filter
namespace Polynomial
open Polynomial
| Mathlib/Topology/Algebra/Polynomial.lean | 105 | 120 | theorem tendsto_abv_eval₂_atTop {R S k α : Type*} [Semiring R] [Ring S] [LinearOrderedField k]
(f : R →+* S) (abv : S → k) [IsAbsoluteValue abv] (p : R[X]) (hd : 0 < degree p)
(hf : f p.leadingCoeff ≠ 0) {l : Filter α} {z : α → S} (hz : Tendsto (abv ∘ z) l atTop) :
Tendsto (fun x => abv (p.eval₂ f (z x))) l atTop := by |
revert hf; refine degree_pos_induction_on p hd ?_ ?_ ?_ <;> clear hd p
· rintro _ - hc
rw [leadingCoeff_mul_X, leadingCoeff_C] at hc
simpa [abv_mul abv] using hz.const_mul_atTop ((abv_pos abv).2 hc)
· intro _ _ ihp hf
rw [leadingCoeff_mul_X] at hf
simpa [abv_mul abv] using (ihp hf).atTop_mul_atTop hz
· intro _ a hd ihp hf
rw [add_comm, leadingCoeff_add_of_degree_lt (degree_C_le.trans_lt hd)] at hf
refine tendsto_atTop_of_add_const_right (abv (-f a)) ?_
refine tendsto_atTop_mono (fun _ => abv_add abv _ _) ?_
simpa using ihp hf
| 2,011 |
import Mathlib.Algebra.Polynomial.AlgebraMap
import Mathlib.Algebra.Polynomial.Inductions
import Mathlib.Algebra.Polynomial.Splits
import Mathlib.Analysis.Normed.Field.Basic
import Mathlib.RingTheory.Polynomial.Vieta
#align_import topology.algebra.polynomial from "leanprover-community/mathlib"@"565eb991e264d0db702722b4bde52ee5173c9950"
open IsAbsoluteValue Filter
namespace Polynomial
open Polynomial
theorem tendsto_abv_eval₂_atTop {R S k α : Type*} [Semiring R] [Ring S] [LinearOrderedField k]
(f : R →+* S) (abv : S → k) [IsAbsoluteValue abv] (p : R[X]) (hd : 0 < degree p)
(hf : f p.leadingCoeff ≠ 0) {l : Filter α} {z : α → S} (hz : Tendsto (abv ∘ z) l atTop) :
Tendsto (fun x => abv (p.eval₂ f (z x))) l atTop := by
revert hf; refine degree_pos_induction_on p hd ?_ ?_ ?_ <;> clear hd p
· rintro _ - hc
rw [leadingCoeff_mul_X, leadingCoeff_C] at hc
simpa [abv_mul abv] using hz.const_mul_atTop ((abv_pos abv).2 hc)
· intro _ _ ihp hf
rw [leadingCoeff_mul_X] at hf
simpa [abv_mul abv] using (ihp hf).atTop_mul_atTop hz
· intro _ a hd ihp hf
rw [add_comm, leadingCoeff_add_of_degree_lt (degree_C_le.trans_lt hd)] at hf
refine tendsto_atTop_of_add_const_right (abv (-f a)) ?_
refine tendsto_atTop_mono (fun _ => abv_add abv _ _) ?_
simpa using ihp hf
#align polynomial.tendsto_abv_eval₂_at_top Polynomial.tendsto_abv_eval₂_atTop
| Mathlib/Topology/Algebra/Polynomial.lean | 123 | 127 | theorem tendsto_abv_atTop {R k α : Type*} [Ring R] [LinearOrderedField k] (abv : R → k)
[IsAbsoluteValue abv] (p : R[X]) (h : 0 < degree p) {l : Filter α} {z : α → R}
(hz : Tendsto (abv ∘ z) l atTop) : Tendsto (fun x => abv (p.eval (z x))) l atTop := by |
apply tendsto_abv_eval₂_atTop _ _ _ h _ hz
exact mt leadingCoeff_eq_zero.1 (ne_zero_of_degree_gt h)
| 2,011 |
import Mathlib.Topology.Algebra.Polynomial
import Mathlib.Topology.ContinuousFunction.Algebra
import Mathlib.Topology.UnitInterval
import Mathlib.Algebra.Star.Subalgebra
#align_import topology.continuous_function.polynomial from "leanprover-community/mathlib"@"a148d797a1094ab554ad4183a4ad6f130358ef64"
variable {R : Type*}
open Polynomial
namespace Polynomial
section
variable [Semiring R] [TopologicalSpace R] [TopologicalSemiring R]
@[simps]
def toContinuousMap (p : R[X]) : C(R, R) :=
⟨fun x : R => p.eval x, by fun_prop⟩
#align polynomial.to_continuous_map Polynomial.toContinuousMap
open ContinuousMap in
lemma toContinuousMap_X_eq_id : X.toContinuousMap = .id R := by
ext; simp
@[simps]
def toContinuousMapOn (p : R[X]) (X : Set R) : C(X, R) :=
-- Porting note: Old proof was `⟨fun x : X => p.toContinuousMap x, by continuity⟩`
⟨fun x : X => p.toContinuousMap x, Continuous.comp (by continuity) (by continuity)⟩
#align polynomial.to_continuous_map_on Polynomial.toContinuousMapOn
open ContinuousMap in
lemma toContinuousMapOn_X_eq_restrict_id (s : Set R) :
X.toContinuousMapOn s = restrict s (.id R) := by
ext; simp
-- TODO some lemmas about when `toContinuousMapOn` is injective?
end
section
variable {α : Type*} [TopologicalSpace α] [CommSemiring R] [TopologicalSpace R]
[TopologicalSemiring R]
@[simp]
| Mathlib/Topology/ContinuousFunction/Polynomial.lean | 76 | 82 | theorem aeval_continuousMap_apply (g : R[X]) (f : C(α, R)) (x : α) :
((Polynomial.aeval f) g) x = g.eval (f x) := by |
refine Polynomial.induction_on' g ?_ ?_
· intro p q hp hq
simp [hp, hq]
· intro n a
simp [Pi.pow_apply]
| 2,012 |
import Mathlib.Analysis.SpecificLimits.Basic
import Mathlib.RingTheory.Polynomial.Bernstein
import Mathlib.Topology.ContinuousFunction.Polynomial
import Mathlib.Topology.ContinuousFunction.Compact
#align_import analysis.special_functions.bernstein from "leanprover-community/mathlib"@"2c1d8ca2812b64f88992a5294ea3dba144755cd1"
set_option linter.uppercaseLean3 false -- S
noncomputable section
open scoped Classical BoundedContinuousFunction unitInterval
def bernstein (n ν : ℕ) : C(I, ℝ) :=
(bernsteinPolynomial ℝ n ν).toContinuousMapOn I
#align bernstein bernstein
@[simp]
| Mathlib/Analysis/SpecialFunctions/Bernstein.lean | 61 | 64 | theorem bernstein_apply (n ν : ℕ) (x : I) :
bernstein n ν x = (n.choose ν : ℝ) * (x : ℝ) ^ ν * (1 - (x : ℝ)) ^ (n - ν) := by |
dsimp [bernstein, Polynomial.toContinuousMapOn, Polynomial.toContinuousMap, bernsteinPolynomial]
simp
| 2,013 |
import Mathlib.Analysis.SpecificLimits.Basic
import Mathlib.RingTheory.Polynomial.Bernstein
import Mathlib.Topology.ContinuousFunction.Polynomial
import Mathlib.Topology.ContinuousFunction.Compact
#align_import analysis.special_functions.bernstein from "leanprover-community/mathlib"@"2c1d8ca2812b64f88992a5294ea3dba144755cd1"
set_option linter.uppercaseLean3 false -- S
noncomputable section
open scoped Classical BoundedContinuousFunction unitInterval
def bernstein (n ν : ℕ) : C(I, ℝ) :=
(bernsteinPolynomial ℝ n ν).toContinuousMapOn I
#align bernstein bernstein
@[simp]
theorem bernstein_apply (n ν : ℕ) (x : I) :
bernstein n ν x = (n.choose ν : ℝ) * (x : ℝ) ^ ν * (1 - (x : ℝ)) ^ (n - ν) := by
dsimp [bernstein, Polynomial.toContinuousMapOn, Polynomial.toContinuousMap, bernsteinPolynomial]
simp
#align bernstein_apply bernstein_apply
| Mathlib/Analysis/SpecialFunctions/Bernstein.lean | 67 | 71 | theorem bernstein_nonneg {n ν : ℕ} {x : I} : 0 ≤ bernstein n ν x := by |
simp only [bernstein_apply]
have h₁ : (0:ℝ) ≤ x := by unit_interval
have h₂ : (0:ℝ) ≤ 1 - x := by unit_interval
positivity
| 2,013 |
import Mathlib.Analysis.SpecificLimits.Basic
import Mathlib.RingTheory.Polynomial.Bernstein
import Mathlib.Topology.ContinuousFunction.Polynomial
import Mathlib.Topology.ContinuousFunction.Compact
#align_import analysis.special_functions.bernstein from "leanprover-community/mathlib"@"2c1d8ca2812b64f88992a5294ea3dba144755cd1"
set_option linter.uppercaseLean3 false -- S
noncomputable section
open scoped Classical BoundedContinuousFunction unitInterval
def bernstein (n ν : ℕ) : C(I, ℝ) :=
(bernsteinPolynomial ℝ n ν).toContinuousMapOn I
#align bernstein bernstein
@[simp]
theorem bernstein_apply (n ν : ℕ) (x : I) :
bernstein n ν x = (n.choose ν : ℝ) * (x : ℝ) ^ ν * (1 - (x : ℝ)) ^ (n - ν) := by
dsimp [bernstein, Polynomial.toContinuousMapOn, Polynomial.toContinuousMap, bernsteinPolynomial]
simp
#align bernstein_apply bernstein_apply
theorem bernstein_nonneg {n ν : ℕ} {x : I} : 0 ≤ bernstein n ν x := by
simp only [bernstein_apply]
have h₁ : (0:ℝ) ≤ x := by unit_interval
have h₂ : (0:ℝ) ≤ 1 - x := by unit_interval
positivity
#align bernstein_nonneg bernstein_nonneg
namespace bernstein
def z {n : ℕ} (k : Fin (n + 1)) : I :=
⟨(k : ℝ) / n, by
cases' n with n
· norm_num
· have h₁ : 0 < (n.succ : ℝ) := mod_cast Nat.succ_pos _
have h₂ : ↑k ≤ n.succ := mod_cast Fin.le_last k
rw [Set.mem_Icc, le_div_iff h₁, div_le_iff h₁]
norm_cast
simp [h₂]⟩
#align bernstein.z bernstein.z
local postfix:90 "/ₙ" => z
| Mathlib/Analysis/SpecialFunctions/Bernstein.lean | 109 | 114 | theorem probability (n : ℕ) (x : I) : (∑ k : Fin (n + 1), bernstein n k x) = 1 := by |
have := bernsteinPolynomial.sum ℝ n
apply_fun fun p => Polynomial.aeval (x : ℝ) p at this
simp? [AlgHom.map_sum, Finset.sum_range] at this says
simp only [Finset.sum_range, map_sum, Polynomial.coe_aeval_eq_eval, map_one] at this
exact this
| 2,013 |
import Mathlib.Analysis.SpecificLimits.Basic
import Mathlib.RingTheory.Polynomial.Bernstein
import Mathlib.Topology.ContinuousFunction.Polynomial
import Mathlib.Topology.ContinuousFunction.Compact
#align_import analysis.special_functions.bernstein from "leanprover-community/mathlib"@"2c1d8ca2812b64f88992a5294ea3dba144755cd1"
set_option linter.uppercaseLean3 false -- S
noncomputable section
open scoped Classical BoundedContinuousFunction unitInterval
def bernstein (n ν : ℕ) : C(I, ℝ) :=
(bernsteinPolynomial ℝ n ν).toContinuousMapOn I
#align bernstein bernstein
@[simp]
theorem bernstein_apply (n ν : ℕ) (x : I) :
bernstein n ν x = (n.choose ν : ℝ) * (x : ℝ) ^ ν * (1 - (x : ℝ)) ^ (n - ν) := by
dsimp [bernstein, Polynomial.toContinuousMapOn, Polynomial.toContinuousMap, bernsteinPolynomial]
simp
#align bernstein_apply bernstein_apply
theorem bernstein_nonneg {n ν : ℕ} {x : I} : 0 ≤ bernstein n ν x := by
simp only [bernstein_apply]
have h₁ : (0:ℝ) ≤ x := by unit_interval
have h₂ : (0:ℝ) ≤ 1 - x := by unit_interval
positivity
#align bernstein_nonneg bernstein_nonneg
namespace bernstein
def z {n : ℕ} (k : Fin (n + 1)) : I :=
⟨(k : ℝ) / n, by
cases' n with n
· norm_num
· have h₁ : 0 < (n.succ : ℝ) := mod_cast Nat.succ_pos _
have h₂ : ↑k ≤ n.succ := mod_cast Fin.le_last k
rw [Set.mem_Icc, le_div_iff h₁, div_le_iff h₁]
norm_cast
simp [h₂]⟩
#align bernstein.z bernstein.z
local postfix:90 "/ₙ" => z
theorem probability (n : ℕ) (x : I) : (∑ k : Fin (n + 1), bernstein n k x) = 1 := by
have := bernsteinPolynomial.sum ℝ n
apply_fun fun p => Polynomial.aeval (x : ℝ) p at this
simp? [AlgHom.map_sum, Finset.sum_range] at this says
simp only [Finset.sum_range, map_sum, Polynomial.coe_aeval_eq_eval, map_one] at this
exact this
#align bernstein.probability bernstein.probability
| Mathlib/Analysis/SpecialFunctions/Bernstein.lean | 117 | 136 | theorem variance {n : ℕ} (h : 0 < (n : ℝ)) (x : I) :
(∑ k : Fin (n + 1), (x - k/ₙ : ℝ) ^ 2 * bernstein n k x) = (x : ℝ) * (1 - x) / n := by |
have h' : (n : ℝ) ≠ 0 := ne_of_gt h
apply_fun fun x : ℝ => x * n using GroupWithZero.mul_right_injective h'
apply_fun fun x : ℝ => x * n using GroupWithZero.mul_right_injective h'
dsimp
conv_lhs => simp only [Finset.sum_mul, z]
conv_rhs => rw [div_mul_cancel₀ _ h']
have := bernsteinPolynomial.variance ℝ n
apply_fun fun p => Polynomial.aeval (x : ℝ) p at this
simp? [AlgHom.map_sum, Finset.sum_range, ← Polynomial.natCast_mul] at this says
simp only [nsmul_eq_mul, Finset.sum_range, map_sum, map_mul, map_pow, map_sub, map_natCast,
Polynomial.aeval_X, Polynomial.coe_aeval_eq_eval, map_one] at this
convert this using 1
· congr 1; funext k
rw [mul_comm _ (n : ℝ), mul_comm _ (n : ℝ), ← mul_assoc, ← mul_assoc]
congr 1
field_simp [h]
ring
· ring
| 2,013 |
import Mathlib.Analysis.SpecialFunctions.Bernstein
import Mathlib.Topology.Algebra.Algebra
#align_import topology.continuous_function.weierstrass from "leanprover-community/mathlib"@"17ef379e997badd73e5eabb4d38f11919ab3c4b3"
open ContinuousMap Filter
open scoped unitInterval
| Mathlib/Topology/ContinuousFunction/Weierstrass.lean | 32 | 44 | theorem polynomialFunctions_closure_eq_top' : (polynomialFunctions I).topologicalClosure = ⊤ := by |
rw [eq_top_iff]
rintro f -
refine Filter.Frequently.mem_closure ?_
refine Filter.Tendsto.frequently (bernsteinApproximation_uniform f) ?_
apply frequently_of_forall
intro n
simp only [SetLike.mem_coe]
apply Subalgebra.sum_mem
rintro n -
apply Subalgebra.smul_mem
dsimp [bernstein, polynomialFunctions]
simp
| 2,014 |
import Mathlib.Analysis.SpecialFunctions.Bernstein
import Mathlib.Topology.Algebra.Algebra
#align_import topology.continuous_function.weierstrass from "leanprover-community/mathlib"@"17ef379e997badd73e5eabb4d38f11919ab3c4b3"
open ContinuousMap Filter
open scoped unitInterval
theorem polynomialFunctions_closure_eq_top' : (polynomialFunctions I).topologicalClosure = ⊤ := by
rw [eq_top_iff]
rintro f -
refine Filter.Frequently.mem_closure ?_
refine Filter.Tendsto.frequently (bernsteinApproximation_uniform f) ?_
apply frequently_of_forall
intro n
simp only [SetLike.mem_coe]
apply Subalgebra.sum_mem
rintro n -
apply Subalgebra.smul_mem
dsimp [bernstein, polynomialFunctions]
simp
#align polynomial_functions_closure_eq_top' polynomialFunctions_closure_eq_top'
| Mathlib/Topology/ContinuousFunction/Weierstrass.lean | 54 | 79 | theorem polynomialFunctions_closure_eq_top (a b : ℝ) :
(polynomialFunctions (Set.Icc a b)).topologicalClosure = ⊤ := by |
cases' lt_or_le a b with h h
-- (Otherwise it's easy; we'll deal with that later.)
· -- We can pullback continuous functions on `[a,b]` to continuous functions on `[0,1]`,
-- by precomposing with an affine map.
let W : C(Set.Icc a b, ℝ) →ₐ[ℝ] C(I, ℝ) :=
compRightAlgHom ℝ ℝ (iccHomeoI a b h).symm.toContinuousMap
-- This operation is itself a homeomorphism
-- (with respect to the norm topologies on continuous functions).
let W' : C(Set.Icc a b, ℝ) ≃ₜ C(I, ℝ) := compRightHomeomorph ℝ (iccHomeoI a b h).symm
have w : (W : C(Set.Icc a b, ℝ) → C(I, ℝ)) = W' := rfl
-- Thus we take the statement of the Weierstrass approximation theorem for `[0,1]`,
have p := polynomialFunctions_closure_eq_top'
-- and pullback both sides, obtaining an equation between subalgebras of `C([a,b], ℝ)`.
apply_fun fun s => s.comap W at p
simp only [Algebra.comap_top] at p
-- Since the pullback operation is continuous, it commutes with taking `topologicalClosure`,
rw [Subalgebra.topologicalClosure_comap_homeomorph _ W W' w] at p
-- and precomposing with an affine map takes polynomial functions to polynomial functions.
rw [polynomialFunctions.comap_compRightAlgHom_iccHomeoI] at p
-- 🎉
exact p
· -- Otherwise, `b ≤ a`, and the interval is a subsingleton,
have : Subsingleton (Set.Icc a b) := (Set.subsingleton_Icc_of_ge h).coe_sort
apply Subsingleton.elim
| 2,014 |
import Mathlib.Analysis.SpecialFunctions.Bernstein
import Mathlib.Topology.Algebra.Algebra
#align_import topology.continuous_function.weierstrass from "leanprover-community/mathlib"@"17ef379e997badd73e5eabb4d38f11919ab3c4b3"
open ContinuousMap Filter
open scoped unitInterval
theorem polynomialFunctions_closure_eq_top' : (polynomialFunctions I).topologicalClosure = ⊤ := by
rw [eq_top_iff]
rintro f -
refine Filter.Frequently.mem_closure ?_
refine Filter.Tendsto.frequently (bernsteinApproximation_uniform f) ?_
apply frequently_of_forall
intro n
simp only [SetLike.mem_coe]
apply Subalgebra.sum_mem
rintro n -
apply Subalgebra.smul_mem
dsimp [bernstein, polynomialFunctions]
simp
#align polynomial_functions_closure_eq_top' polynomialFunctions_closure_eq_top'
theorem polynomialFunctions_closure_eq_top (a b : ℝ) :
(polynomialFunctions (Set.Icc a b)).topologicalClosure = ⊤ := by
cases' lt_or_le a b with h h
-- (Otherwise it's easy; we'll deal with that later.)
· -- We can pullback continuous functions on `[a,b]` to continuous functions on `[0,1]`,
-- by precomposing with an affine map.
let W : C(Set.Icc a b, ℝ) →ₐ[ℝ] C(I, ℝ) :=
compRightAlgHom ℝ ℝ (iccHomeoI a b h).symm.toContinuousMap
-- This operation is itself a homeomorphism
-- (with respect to the norm topologies on continuous functions).
let W' : C(Set.Icc a b, ℝ) ≃ₜ C(I, ℝ) := compRightHomeomorph ℝ (iccHomeoI a b h).symm
have w : (W : C(Set.Icc a b, ℝ) → C(I, ℝ)) = W' := rfl
-- Thus we take the statement of the Weierstrass approximation theorem for `[0,1]`,
have p := polynomialFunctions_closure_eq_top'
-- and pullback both sides, obtaining an equation between subalgebras of `C([a,b], ℝ)`.
apply_fun fun s => s.comap W at p
simp only [Algebra.comap_top] at p
-- Since the pullback operation is continuous, it commutes with taking `topologicalClosure`,
rw [Subalgebra.topologicalClosure_comap_homeomorph _ W W' w] at p
-- and precomposing with an affine map takes polynomial functions to polynomial functions.
rw [polynomialFunctions.comap_compRightAlgHom_iccHomeoI] at p
-- 🎉
exact p
· -- Otherwise, `b ≤ a`, and the interval is a subsingleton,
have : Subsingleton (Set.Icc a b) := (Set.subsingleton_Icc_of_ge h).coe_sort
apply Subsingleton.elim
#align polynomial_functions_closure_eq_top polynomialFunctions_closure_eq_top
| Mathlib/Topology/ContinuousFunction/Weierstrass.lean | 86 | 89 | theorem continuousMap_mem_polynomialFunctions_closure (a b : ℝ) (f : C(Set.Icc a b, ℝ)) :
f ∈ (polynomialFunctions (Set.Icc a b)).topologicalClosure := by |
rw [polynomialFunctions_closure_eq_top _ _]
simp
| 2,014 |
import Mathlib.Analysis.SpecialFunctions.Bernstein
import Mathlib.Topology.Algebra.Algebra
#align_import topology.continuous_function.weierstrass from "leanprover-community/mathlib"@"17ef379e997badd73e5eabb4d38f11919ab3c4b3"
open ContinuousMap Filter
open scoped unitInterval
theorem polynomialFunctions_closure_eq_top' : (polynomialFunctions I).topologicalClosure = ⊤ := by
rw [eq_top_iff]
rintro f -
refine Filter.Frequently.mem_closure ?_
refine Filter.Tendsto.frequently (bernsteinApproximation_uniform f) ?_
apply frequently_of_forall
intro n
simp only [SetLike.mem_coe]
apply Subalgebra.sum_mem
rintro n -
apply Subalgebra.smul_mem
dsimp [bernstein, polynomialFunctions]
simp
#align polynomial_functions_closure_eq_top' polynomialFunctions_closure_eq_top'
theorem polynomialFunctions_closure_eq_top (a b : ℝ) :
(polynomialFunctions (Set.Icc a b)).topologicalClosure = ⊤ := by
cases' lt_or_le a b with h h
-- (Otherwise it's easy; we'll deal with that later.)
· -- We can pullback continuous functions on `[a,b]` to continuous functions on `[0,1]`,
-- by precomposing with an affine map.
let W : C(Set.Icc a b, ℝ) →ₐ[ℝ] C(I, ℝ) :=
compRightAlgHom ℝ ℝ (iccHomeoI a b h).symm.toContinuousMap
-- This operation is itself a homeomorphism
-- (with respect to the norm topologies on continuous functions).
let W' : C(Set.Icc a b, ℝ) ≃ₜ C(I, ℝ) := compRightHomeomorph ℝ (iccHomeoI a b h).symm
have w : (W : C(Set.Icc a b, ℝ) → C(I, ℝ)) = W' := rfl
-- Thus we take the statement of the Weierstrass approximation theorem for `[0,1]`,
have p := polynomialFunctions_closure_eq_top'
-- and pullback both sides, obtaining an equation between subalgebras of `C([a,b], ℝ)`.
apply_fun fun s => s.comap W at p
simp only [Algebra.comap_top] at p
-- Since the pullback operation is continuous, it commutes with taking `topologicalClosure`,
rw [Subalgebra.topologicalClosure_comap_homeomorph _ W W' w] at p
-- and precomposing with an affine map takes polynomial functions to polynomial functions.
rw [polynomialFunctions.comap_compRightAlgHom_iccHomeoI] at p
-- 🎉
exact p
· -- Otherwise, `b ≤ a`, and the interval is a subsingleton,
have : Subsingleton (Set.Icc a b) := (Set.subsingleton_Icc_of_ge h).coe_sort
apply Subsingleton.elim
#align polynomial_functions_closure_eq_top polynomialFunctions_closure_eq_top
theorem continuousMap_mem_polynomialFunctions_closure (a b : ℝ) (f : C(Set.Icc a b, ℝ)) :
f ∈ (polynomialFunctions (Set.Icc a b)).topologicalClosure := by
rw [polynomialFunctions_closure_eq_top _ _]
simp
#align continuous_map_mem_polynomial_functions_closure continuousMap_mem_polynomialFunctions_closure
open scoped Polynomial
| Mathlib/Topology/ContinuousFunction/Weierstrass.lean | 99 | 105 | theorem exists_polynomial_near_continuousMap (a b : ℝ) (f : C(Set.Icc a b, ℝ)) (ε : ℝ)
(pos : 0 < ε) : ∃ p : ℝ[X], ‖p.toContinuousMapOn _ - f‖ < ε := by |
have w := mem_closure_iff_frequently.mp (continuousMap_mem_polynomialFunctions_closure _ _ f)
rw [Metric.nhds_basis_ball.frequently_iff] at w
obtain ⟨-, H, ⟨m, ⟨-, rfl⟩⟩⟩ := w ε pos
rw [Metric.mem_ball, dist_eq_norm] at H
exact ⟨m, H⟩
| 2,014 |
import Mathlib.Analysis.SpecialFunctions.Bernstein
import Mathlib.Topology.Algebra.Algebra
#align_import topology.continuous_function.weierstrass from "leanprover-community/mathlib"@"17ef379e997badd73e5eabb4d38f11919ab3c4b3"
open ContinuousMap Filter
open scoped unitInterval
theorem polynomialFunctions_closure_eq_top' : (polynomialFunctions I).topologicalClosure = ⊤ := by
rw [eq_top_iff]
rintro f -
refine Filter.Frequently.mem_closure ?_
refine Filter.Tendsto.frequently (bernsteinApproximation_uniform f) ?_
apply frequently_of_forall
intro n
simp only [SetLike.mem_coe]
apply Subalgebra.sum_mem
rintro n -
apply Subalgebra.smul_mem
dsimp [bernstein, polynomialFunctions]
simp
#align polynomial_functions_closure_eq_top' polynomialFunctions_closure_eq_top'
theorem polynomialFunctions_closure_eq_top (a b : ℝ) :
(polynomialFunctions (Set.Icc a b)).topologicalClosure = ⊤ := by
cases' lt_or_le a b with h h
-- (Otherwise it's easy; we'll deal with that later.)
· -- We can pullback continuous functions on `[a,b]` to continuous functions on `[0,1]`,
-- by precomposing with an affine map.
let W : C(Set.Icc a b, ℝ) →ₐ[ℝ] C(I, ℝ) :=
compRightAlgHom ℝ ℝ (iccHomeoI a b h).symm.toContinuousMap
-- This operation is itself a homeomorphism
-- (with respect to the norm topologies on continuous functions).
let W' : C(Set.Icc a b, ℝ) ≃ₜ C(I, ℝ) := compRightHomeomorph ℝ (iccHomeoI a b h).symm
have w : (W : C(Set.Icc a b, ℝ) → C(I, ℝ)) = W' := rfl
-- Thus we take the statement of the Weierstrass approximation theorem for `[0,1]`,
have p := polynomialFunctions_closure_eq_top'
-- and pullback both sides, obtaining an equation between subalgebras of `C([a,b], ℝ)`.
apply_fun fun s => s.comap W at p
simp only [Algebra.comap_top] at p
-- Since the pullback operation is continuous, it commutes with taking `topologicalClosure`,
rw [Subalgebra.topologicalClosure_comap_homeomorph _ W W' w] at p
-- and precomposing with an affine map takes polynomial functions to polynomial functions.
rw [polynomialFunctions.comap_compRightAlgHom_iccHomeoI] at p
-- 🎉
exact p
· -- Otherwise, `b ≤ a`, and the interval is a subsingleton,
have : Subsingleton (Set.Icc a b) := (Set.subsingleton_Icc_of_ge h).coe_sort
apply Subsingleton.elim
#align polynomial_functions_closure_eq_top polynomialFunctions_closure_eq_top
theorem continuousMap_mem_polynomialFunctions_closure (a b : ℝ) (f : C(Set.Icc a b, ℝ)) :
f ∈ (polynomialFunctions (Set.Icc a b)).topologicalClosure := by
rw [polynomialFunctions_closure_eq_top _ _]
simp
#align continuous_map_mem_polynomial_functions_closure continuousMap_mem_polynomialFunctions_closure
open scoped Polynomial
theorem exists_polynomial_near_continuousMap (a b : ℝ) (f : C(Set.Icc a b, ℝ)) (ε : ℝ)
(pos : 0 < ε) : ∃ p : ℝ[X], ‖p.toContinuousMapOn _ - f‖ < ε := by
have w := mem_closure_iff_frequently.mp (continuousMap_mem_polynomialFunctions_closure _ _ f)
rw [Metric.nhds_basis_ball.frequently_iff] at w
obtain ⟨-, H, ⟨m, ⟨-, rfl⟩⟩⟩ := w ε pos
rw [Metric.mem_ball, dist_eq_norm] at H
exact ⟨m, H⟩
#align exists_polynomial_near_continuous_map exists_polynomial_near_continuousMap
| Mathlib/Topology/ContinuousFunction/Weierstrass.lean | 114 | 122 | theorem exists_polynomial_near_of_continuousOn (a b : ℝ) (f : ℝ → ℝ)
(c : ContinuousOn f (Set.Icc a b)) (ε : ℝ) (pos : 0 < ε) :
∃ p : ℝ[X], ∀ x ∈ Set.Icc a b, |p.eval x - f x| < ε := by |
let f' : C(Set.Icc a b, ℝ) := ⟨fun x => f x, continuousOn_iff_continuous_restrict.mp c⟩
obtain ⟨p, b⟩ := exists_polynomial_near_continuousMap a b f' ε pos
use p
rw [norm_lt_iff _ pos] at b
intro x m
exact b ⟨x, m⟩
| 2,014 |
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"
noncomputable section
namespace ContinuousMap
variable {X : Type*} [TopologicalSpace X] [CompactSpace X]
open scoped Polynomial
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
| Mathlib/Topology/ContinuousFunction/StoneWeierstrass.lean | 69 | 77 | 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]
| 2,015 |
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"
noncomputable section
namespace ContinuousMap
variable {X : Type*} [TopologicalSpace X] [CompactSpace X]
open scoped Polynomial
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
| Mathlib/Topology/ContinuousFunction/StoneWeierstrass.lean | 88 | 91 | 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
| 2,015 |
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"
noncomputable section
namespace ContinuousMap
variable {X : Type*} [TopologicalSpace X] [CompactSpace X]
open scoped Polynomial
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
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
| 2,015 |
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"
noncomputable section
namespace ContinuousMap
variable {X : Type*} [TopologicalSpace X] [CompactSpace X]
open scoped Polynomial
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
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
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
#align continuous_map.comp_attach_bound_mem_closure ContinuousMap.comp_attachBound_mem_closure
| Mathlib/Topology/ContinuousFunction/StoneWeierstrass.lean | 116 | 121 | theorem abs_mem_subalgebra_closure (A : Subalgebra ℝ C(X, ℝ)) (f : A) :
|(f : C(X, ℝ))| ∈ A.topologicalClosure := by |
let f' := attachBound (f : C(X, ℝ))
let abs : C(Set.Icc (-‖f‖) ‖f‖, ℝ) := { toFun := fun x : Set.Icc (-‖f‖) ‖f‖ => |(x : ℝ)| }
change abs.comp f' ∈ A.topologicalClosure
apply comp_attachBound_mem_closure
| 2,015 |
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"
noncomputable section
namespace ContinuousMap
variable {X : Type*} [TopologicalSpace X] [CompactSpace X]
open scoped Polynomial
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
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
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
#align continuous_map.comp_attach_bound_mem_closure ContinuousMap.comp_attachBound_mem_closure
theorem abs_mem_subalgebra_closure (A : Subalgebra ℝ C(X, ℝ)) (f : A) :
|(f : C(X, ℝ))| ∈ A.topologicalClosure := by
let f' := attachBound (f : C(X, ℝ))
let abs : C(Set.Icc (-‖f‖) ‖f‖, ℝ) := { toFun := fun x : Set.Icc (-‖f‖) ‖f‖ => |(x : ℝ)| }
change abs.comp f' ∈ A.topologicalClosure
apply comp_attachBound_mem_closure
#align continuous_map.abs_mem_subalgebra_closure ContinuousMap.abs_mem_subalgebra_closure
| Mathlib/Topology/ContinuousFunction/StoneWeierstrass.lean | 124 | 134 | theorem inf_mem_subalgebra_closure (A : Subalgebra ℝ C(X, ℝ)) (f g : A) :
(f : C(X, ℝ)) ⊓ (g : C(X, ℝ)) ∈ A.topologicalClosure := by |
rw [inf_eq_half_smul_add_sub_abs_sub' ℝ]
refine
A.topologicalClosure.smul_mem
(A.topologicalClosure.sub_mem
(A.topologicalClosure.add_mem (A.le_topologicalClosure f.property)
(A.le_topologicalClosure g.property))
?_)
_
exact mod_cast abs_mem_subalgebra_closure A _
| 2,015 |
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"
noncomputable section
namespace ContinuousMap
variable {X : Type*} [TopologicalSpace X] [CompactSpace X]
open scoped Polynomial
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
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
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
#align continuous_map.comp_attach_bound_mem_closure ContinuousMap.comp_attachBound_mem_closure
theorem abs_mem_subalgebra_closure (A : Subalgebra ℝ C(X, ℝ)) (f : A) :
|(f : C(X, ℝ))| ∈ A.topologicalClosure := by
let f' := attachBound (f : C(X, ℝ))
let abs : C(Set.Icc (-‖f‖) ‖f‖, ℝ) := { toFun := fun x : Set.Icc (-‖f‖) ‖f‖ => |(x : ℝ)| }
change abs.comp f' ∈ A.topologicalClosure
apply comp_attachBound_mem_closure
#align continuous_map.abs_mem_subalgebra_closure ContinuousMap.abs_mem_subalgebra_closure
theorem inf_mem_subalgebra_closure (A : Subalgebra ℝ C(X, ℝ)) (f g : A) :
(f : C(X, ℝ)) ⊓ (g : C(X, ℝ)) ∈ A.topologicalClosure := by
rw [inf_eq_half_smul_add_sub_abs_sub' ℝ]
refine
A.topologicalClosure.smul_mem
(A.topologicalClosure.sub_mem
(A.topologicalClosure.add_mem (A.le_topologicalClosure f.property)
(A.le_topologicalClosure g.property))
?_)
_
exact mod_cast abs_mem_subalgebra_closure A _
#align continuous_map.inf_mem_subalgebra_closure ContinuousMap.inf_mem_subalgebra_closure
| Mathlib/Topology/ContinuousFunction/StoneWeierstrass.lean | 137 | 143 | theorem inf_mem_closed_subalgebra (A : Subalgebra ℝ C(X, ℝ)) (h : IsClosed (A : Set C(X, ℝ)))
(f g : A) : (f : C(X, ℝ)) ⊓ (g : C(X, ℝ)) ∈ A := by |
convert inf_mem_subalgebra_closure A f g
apply SetLike.ext'
symm
erw [closure_eq_iff_isClosed]
exact h
| 2,015 |
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"
noncomputable section
namespace ContinuousMap
variable {X : Type*} [TopologicalSpace X] [CompactSpace X]
open scoped Polynomial
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
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
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
#align continuous_map.comp_attach_bound_mem_closure ContinuousMap.comp_attachBound_mem_closure
theorem abs_mem_subalgebra_closure (A : Subalgebra ℝ C(X, ℝ)) (f : A) :
|(f : C(X, ℝ))| ∈ A.topologicalClosure := by
let f' := attachBound (f : C(X, ℝ))
let abs : C(Set.Icc (-‖f‖) ‖f‖, ℝ) := { toFun := fun x : Set.Icc (-‖f‖) ‖f‖ => |(x : ℝ)| }
change abs.comp f' ∈ A.topologicalClosure
apply comp_attachBound_mem_closure
#align continuous_map.abs_mem_subalgebra_closure ContinuousMap.abs_mem_subalgebra_closure
theorem inf_mem_subalgebra_closure (A : Subalgebra ℝ C(X, ℝ)) (f g : A) :
(f : C(X, ℝ)) ⊓ (g : C(X, ℝ)) ∈ A.topologicalClosure := by
rw [inf_eq_half_smul_add_sub_abs_sub' ℝ]
refine
A.topologicalClosure.smul_mem
(A.topologicalClosure.sub_mem
(A.topologicalClosure.add_mem (A.le_topologicalClosure f.property)
(A.le_topologicalClosure g.property))
?_)
_
exact mod_cast abs_mem_subalgebra_closure A _
#align continuous_map.inf_mem_subalgebra_closure ContinuousMap.inf_mem_subalgebra_closure
theorem inf_mem_closed_subalgebra (A : Subalgebra ℝ C(X, ℝ)) (h : IsClosed (A : Set C(X, ℝ)))
(f g : A) : (f : C(X, ℝ)) ⊓ (g : C(X, ℝ)) ∈ A := by
convert inf_mem_subalgebra_closure A f g
apply SetLike.ext'
symm
erw [closure_eq_iff_isClosed]
exact h
#align continuous_map.inf_mem_closed_subalgebra ContinuousMap.inf_mem_closed_subalgebra
| Mathlib/Topology/ContinuousFunction/StoneWeierstrass.lean | 146 | 156 | theorem sup_mem_subalgebra_closure (A : Subalgebra ℝ C(X, ℝ)) (f g : A) :
(f : C(X, ℝ)) ⊔ (g : C(X, ℝ)) ∈ A.topologicalClosure := by |
rw [sup_eq_half_smul_add_add_abs_sub' ℝ]
refine
A.topologicalClosure.smul_mem
(A.topologicalClosure.add_mem
(A.topologicalClosure.add_mem (A.le_topologicalClosure f.property)
(A.le_topologicalClosure g.property))
?_)
_
exact mod_cast abs_mem_subalgebra_closure A _
| 2,015 |
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"
noncomputable section
namespace ContinuousMap
variable {X : Type*} [TopologicalSpace X] [CompactSpace X]
open scoped Polynomial
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
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
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
#align continuous_map.comp_attach_bound_mem_closure ContinuousMap.comp_attachBound_mem_closure
theorem abs_mem_subalgebra_closure (A : Subalgebra ℝ C(X, ℝ)) (f : A) :
|(f : C(X, ℝ))| ∈ A.topologicalClosure := by
let f' := attachBound (f : C(X, ℝ))
let abs : C(Set.Icc (-‖f‖) ‖f‖, ℝ) := { toFun := fun x : Set.Icc (-‖f‖) ‖f‖ => |(x : ℝ)| }
change abs.comp f' ∈ A.topologicalClosure
apply comp_attachBound_mem_closure
#align continuous_map.abs_mem_subalgebra_closure ContinuousMap.abs_mem_subalgebra_closure
theorem inf_mem_subalgebra_closure (A : Subalgebra ℝ C(X, ℝ)) (f g : A) :
(f : C(X, ℝ)) ⊓ (g : C(X, ℝ)) ∈ A.topologicalClosure := by
rw [inf_eq_half_smul_add_sub_abs_sub' ℝ]
refine
A.topologicalClosure.smul_mem
(A.topologicalClosure.sub_mem
(A.topologicalClosure.add_mem (A.le_topologicalClosure f.property)
(A.le_topologicalClosure g.property))
?_)
_
exact mod_cast abs_mem_subalgebra_closure A _
#align continuous_map.inf_mem_subalgebra_closure ContinuousMap.inf_mem_subalgebra_closure
theorem inf_mem_closed_subalgebra (A : Subalgebra ℝ C(X, ℝ)) (h : IsClosed (A : Set C(X, ℝ)))
(f g : A) : (f : C(X, ℝ)) ⊓ (g : C(X, ℝ)) ∈ A := by
convert inf_mem_subalgebra_closure A f g
apply SetLike.ext'
symm
erw [closure_eq_iff_isClosed]
exact h
#align continuous_map.inf_mem_closed_subalgebra ContinuousMap.inf_mem_closed_subalgebra
theorem sup_mem_subalgebra_closure (A : Subalgebra ℝ C(X, ℝ)) (f g : A) :
(f : C(X, ℝ)) ⊔ (g : C(X, ℝ)) ∈ A.topologicalClosure := by
rw [sup_eq_half_smul_add_add_abs_sub' ℝ]
refine
A.topologicalClosure.smul_mem
(A.topologicalClosure.add_mem
(A.topologicalClosure.add_mem (A.le_topologicalClosure f.property)
(A.le_topologicalClosure g.property))
?_)
_
exact mod_cast abs_mem_subalgebra_closure A _
#align continuous_map.sup_mem_subalgebra_closure ContinuousMap.sup_mem_subalgebra_closure
| Mathlib/Topology/ContinuousFunction/StoneWeierstrass.lean | 159 | 165 | theorem sup_mem_closed_subalgebra (A : Subalgebra ℝ C(X, ℝ)) (h : IsClosed (A : Set C(X, ℝ)))
(f g : A) : (f : C(X, ℝ)) ⊔ (g : C(X, ℝ)) ∈ A := by |
convert sup_mem_subalgebra_closure A f g
apply SetLike.ext'
symm
erw [closure_eq_iff_isClosed]
exact h
| 2,015 |
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"
noncomputable section
section RCLike
open RCLike
-- Redefine `X`, since for the next lemma it need not be compact
variable {𝕜 : Type*} {X : Type*} [RCLike 𝕜] [TopologicalSpace X]
open ContinuousMap
#noalign continuous_map.conj_invariant_subalgebra
#noalign continuous_map.mem_conj_invariant_subalgebra
#noalign continuous_map.subalgebra_conj_invariant
| Mathlib/Topology/ContinuousFunction/StoneWeierstrass.lean | 355 | 377 | theorem Subalgebra.SeparatesPoints.rclike_to_real {A : StarSubalgebra 𝕜 C(X, 𝕜)}
(hA : A.SeparatesPoints) :
((A.restrictScalars ℝ).comap
(ofRealAm.compLeftContinuous ℝ continuous_ofReal)).SeparatesPoints := by |
intro x₁ x₂ hx
-- Let `f` in the subalgebra `A` separate the points `x₁`, `x₂`
obtain ⟨_, ⟨f, hfA, rfl⟩, hf⟩ := hA hx
let F : C(X, 𝕜) := f - const _ (f x₂)
-- Subtract the constant `f x₂` from `f`; this is still an element of the subalgebra
have hFA : F ∈ A := by
refine A.sub_mem hfA (@Eq.subst _ (· ∈ A) _ _ ?_ <| A.smul_mem A.one_mem <| f x₂)
ext1
simp only [coe_smul, coe_one, smul_apply, one_apply, Algebra.id.smul_eq_mul, mul_one,
const_apply]
-- Consider now the function `fun x ↦ |f x - f x₂| ^ 2`
refine ⟨_, ⟨⟨(‖F ·‖ ^ 2), by continuity⟩, ?_, rfl⟩, ?_⟩
· -- This is also an element of the subalgebra, and takes only real values
rw [SetLike.mem_coe, Subalgebra.mem_comap]
convert (A.restrictScalars ℝ).mul_mem hFA (star_mem hFA : star F ∈ A)
ext1
simp [← RCLike.mul_conj]
· -- And it also separates the points `x₁`, `x₂`
simpa [F] using sub_ne_zero.mpr hf
| 2,015 |
import Mathlib.Algebra.Polynomial.Identities
import Mathlib.Analysis.SpecificLimits.Basic
import Mathlib.NumberTheory.Padics.PadicIntegers
import Mathlib.Topology.Algebra.Polynomial
import Mathlib.Topology.MetricSpace.CauSeqFilter
#align_import number_theory.padics.hensel from "leanprover-community/mathlib"@"f2ce6086713c78a7f880485f7917ea547a215982"
noncomputable section
open scoped Classical
open Topology
-- We begin with some general lemmas that are used below in the computation.
| Mathlib/NumberTheory/Padics/Hensel.lean | 43 | 49 | theorem padic_polynomial_dist {p : ℕ} [Fact p.Prime] (F : Polynomial ℤ_[p]) (x y : ℤ_[p]) :
‖F.eval x - F.eval y‖ ≤ ‖x - y‖ :=
let ⟨z, hz⟩ := F.evalSubFactor x y
calc
‖F.eval x - F.eval y‖ = ‖z‖ * ‖x - y‖ := by | simp [hz]
_ ≤ 1 * ‖x - y‖ := by gcongr; apply PadicInt.norm_le_one
_ = ‖x - y‖ := by simp
| 2,016 |
import Mathlib.Algebra.Algebra.Quasispectrum
import Mathlib.Algebra.Algebra.Spectrum
import Mathlib.Algebra.Star.Order
import Mathlib.Topology.Algebra.Polynomial
import Mathlib.Topology.ContinuousFunction.Algebra
section Basic
class ContinuousFunctionalCalculus (R : Type*) {A : Type*} (p : outParam (A → Prop))
[CommSemiring R] [StarRing R] [MetricSpace R] [TopologicalSemiring R] [ContinuousStar R]
[Ring A] [StarRing A] [TopologicalSpace A] [Algebra R A] : Prop where
exists_cfc_of_predicate : ∀ a, p a → ∃ φ : C(spectrum R a, R) →⋆ₐ[R] A,
ClosedEmbedding φ ∧ φ ((ContinuousMap.id R).restrict <| spectrum R a) = a ∧
(∀ f, spectrum R (φ f) = Set.range f) ∧ ∀ f, p (φ f)
class UniqueContinuousFunctionalCalculus (R A : Type*) [CommSemiring R] [StarRing R]
[MetricSpace R] [TopologicalSemiring R] [ContinuousStar R] [Ring A] [StarRing A]
[TopologicalSpace A] [Algebra R A] : Prop where
eq_of_continuous_of_map_id (s : Set R) [CompactSpace s]
(φ ψ : C(s, R) →⋆ₐ[R] A) (hφ : Continuous φ) (hψ : Continuous ψ)
(h : φ (.restrict s <| .id R) = ψ (.restrict s <| .id R)) :
φ = ψ
compactSpace_spectrum (a : A) : CompactSpace (spectrum R a)
variable {R A : Type*} {p : A → Prop} [CommSemiring R] [StarRing R] [MetricSpace R]
variable [TopologicalSemiring R] [ContinuousStar R] [TopologicalSpace A] [Ring A] [StarRing A]
variable [Algebra R A] [ContinuousFunctionalCalculus R p]
lemma StarAlgHom.ext_continuousMap [UniqueContinuousFunctionalCalculus R A]
(a : A) (φ ψ : C(spectrum R a, R) →⋆ₐ[R] A) (hφ : Continuous φ) (hψ : Continuous ψ)
(h : φ (.restrict (spectrum R a) <| .id R) = ψ (.restrict (spectrum R a) <| .id R)) :
φ = ψ :=
have := UniqueContinuousFunctionalCalculus.compactSpace_spectrum (R := R) a
UniqueContinuousFunctionalCalculus.eq_of_continuous_of_map_id (spectrum R a) φ ψ hφ hψ h
section cfcHom
variable {a : A} (ha : p a)
-- Note: since `spectrum R a` is closed, we may always extend `f : C(spectrum R a, R)` to a function
-- of type `C(R, R)` by the Tietze extension theorem (assuming `R` is either `ℝ`, `ℂ` or `ℝ≥0`).
noncomputable def cfcHom : C(spectrum R a, R) →⋆ₐ[R] A :=
(ContinuousFunctionalCalculus.exists_cfc_of_predicate a ha).choose
lemma cfcHom_closedEmbedding :
ClosedEmbedding <| (cfcHom ha : C(spectrum R a, R) →⋆ₐ[R] A) :=
(ContinuousFunctionalCalculus.exists_cfc_of_predicate a ha).choose_spec.1
lemma cfcHom_id :
cfcHom ha ((ContinuousMap.id R).restrict <| spectrum R a) = a :=
(ContinuousFunctionalCalculus.exists_cfc_of_predicate a ha).choose_spec.2.1
lemma cfcHom_map_spectrum (f : C(spectrum R a, R)) :
spectrum R (cfcHom ha f) = Set.range f :=
(ContinuousFunctionalCalculus.exists_cfc_of_predicate a ha).choose_spec.2.2.1 f
lemma cfcHom_predicate (f : C(spectrum R a, R)) :
p (cfcHom ha f) :=
(ContinuousFunctionalCalculus.exists_cfc_of_predicate a ha).choose_spec.2.2.2 f
lemma cfcHom_eq_of_continuous_of_map_id [UniqueContinuousFunctionalCalculus R A]
(φ : C(spectrum R a, R) →⋆ₐ[R] A) (hφ₁ : Continuous φ)
(hφ₂ : φ (.restrict (spectrum R a) <| .id R) = a) : cfcHom ha = φ :=
(cfcHom ha).ext_continuousMap a φ (cfcHom_closedEmbedding ha).continuous hφ₁ <| by
rw [cfcHom_id ha, hφ₂]
| Mathlib/Topology/ContinuousFunction/FunctionalCalculus.lean | 243 | 255 | theorem cfcHom_comp [UniqueContinuousFunctionalCalculus R A] (f : C(spectrum R a, R))
(f' : C(spectrum R a, spectrum R (cfcHom ha f)))
(hff' : ∀ x, f x = f' x) (g : C(spectrum R (cfcHom ha f), R)) :
cfcHom ha (g.comp f') = cfcHom (cfcHom_predicate ha f) g := by |
let φ : C(spectrum R (cfcHom ha f), R) →⋆ₐ[R] A :=
(cfcHom ha).comp <| ContinuousMap.compStarAlgHom' R R f'
suffices cfcHom (cfcHom_predicate ha f) = φ from DFunLike.congr_fun this.symm g
refine cfcHom_eq_of_continuous_of_map_id (cfcHom_predicate ha f) φ ?_ ?_
· exact (cfcHom_closedEmbedding ha).continuous.comp f'.continuous_comp_left
· simp only [φ, StarAlgHom.comp_apply, ContinuousMap.compStarAlgHom'_apply]
congr
ext x
simp [hff']
| 2,017 |
import Mathlib.Algebra.Algebra.Quasispectrum
import Mathlib.Topology.ContinuousFunction.Compact
import Mathlib.Topology.ContinuousFunction.ContinuousMapZero
import Mathlib.Topology.ContinuousFunction.FunctionalCalculus
import Mathlib.Topology.UniformSpace.CompactConvergence
local notation "σₙ" => quasispectrum
open scoped ContinuousMapZero
class NonUnitalContinuousFunctionalCalculus (R : Type*) {A : Type*} (p : outParam (A → Prop))
[CommSemiring R] [Nontrivial R] [StarRing R] [MetricSpace R] [TopologicalSemiring R]
[ContinuousStar R] [NonUnitalRing A] [StarRing A] [TopologicalSpace A] [Module R A]
[IsScalarTower R A A] [SMulCommClass R A A] : Prop where
exists_cfc_of_predicate : ∀ a, p a → ∃ φ : C(σₙ R a, R)₀ →⋆ₙₐ[R] A,
ClosedEmbedding φ ∧ φ ⟨(ContinuousMap.id R).restrict <| σₙ R a, rfl⟩ = a ∧
(∀ f, σₙ R (φ f) = Set.range f) ∧ ∀ f, p (φ f)
-- TODO: try to unify with the unital version. The `ℝ≥0` case makes it tricky.
class UniqueNonUnitalContinuousFunctionalCalculus (R A : Type*) [CommSemiring R] [StarRing R]
[MetricSpace R] [TopologicalSemiring R] [ContinuousStar R] [NonUnitalRing A] [StarRing A]
[TopologicalSpace A] [Module R A] [IsScalarTower R A A] [SMulCommClass R A A] : Prop where
eq_of_continuous_of_map_id (s : Set R) [CompactSpace s] [Zero s] (h0 : (0 : s) = (0 : R))
(φ ψ : C(s, R)₀ →⋆ₙₐ[R] A) (hφ : Continuous φ) (hψ : Continuous ψ)
(h : φ (⟨.restrict s <| .id R, h0⟩) = ψ (⟨.restrict s <| .id R, h0⟩)) :
φ = ψ
compactSpace_quasispectrum (a : A) : CompactSpace (σₙ R a)
section Main
variable {R A : Type*} {p : A → Prop} [CommSemiring R] [Nontrivial R] [StarRing R] [MetricSpace R]
variable [TopologicalSemiring R] [ContinuousStar R] [NonUnitalRing A] [StarRing A]
variable [TopologicalSpace A] [Module R A] [IsScalarTower R A A] [SMulCommClass R A A]
variable [NonUnitalContinuousFunctionalCalculus R p]
lemma NonUnitalStarAlgHom.ext_continuousMap [UniqueNonUnitalContinuousFunctionalCalculus R A]
(a : A) (φ ψ : C(σₙ R a, R)₀ →⋆ₙₐ[R] A) (hφ : Continuous φ) (hψ : Continuous ψ)
(h : φ ⟨.restrict (σₙ R a) <| .id R, rfl⟩ = ψ ⟨.restrict (σₙ R a) <| .id R, rfl⟩) :
φ = ψ :=
have := UniqueNonUnitalContinuousFunctionalCalculus.compactSpace_quasispectrum (R := R) a
UniqueNonUnitalContinuousFunctionalCalculus.eq_of_continuous_of_map_id _ (by simp) φ ψ hφ hψ h
section cfcₙHom
variable {a : A} (ha : p a)
noncomputable def cfcₙHom : C(σₙ R a, R)₀ →⋆ₙₐ[R] A :=
(NonUnitalContinuousFunctionalCalculus.exists_cfc_of_predicate a ha).choose
lemma cfcₙHom_closedEmbedding :
ClosedEmbedding <| (cfcₙHom ha : C(σₙ R a, R)₀ →⋆ₙₐ[R] A) :=
(NonUnitalContinuousFunctionalCalculus.exists_cfc_of_predicate a ha).choose_spec.1
lemma cfcₙHom_id :
cfcₙHom ha ⟨(ContinuousMap.id R).restrict <| σₙ R a, rfl⟩ = a :=
(NonUnitalContinuousFunctionalCalculus.exists_cfc_of_predicate a ha).choose_spec.2.1
lemma cfcₙHom_map_quasispectrum (f : C(σₙ R a, R)₀) :
σₙ R (cfcₙHom ha f) = Set.range f :=
(NonUnitalContinuousFunctionalCalculus.exists_cfc_of_predicate a ha).choose_spec.2.2.1 f
lemma cfcₙHom_predicate (f : C(σₙ R a, R)₀) :
p (cfcₙHom ha f) :=
(NonUnitalContinuousFunctionalCalculus.exists_cfc_of_predicate a ha).choose_spec.2.2.2 f
lemma cfcₙHom_eq_of_continuous_of_map_id [UniqueNonUnitalContinuousFunctionalCalculus R A]
(φ : C(σₙ R a, R)₀ →⋆ₙₐ[R] A) (hφ₁ : Continuous φ)
(hφ₂ : φ ⟨.restrict (σₙ R a) <| .id R, rfl⟩ = a) : cfcₙHom ha = φ :=
(cfcₙHom ha).ext_continuousMap a φ (cfcₙHom_closedEmbedding ha).continuous hφ₁ <| by
rw [cfcₙHom_id ha, hφ₂]
| Mathlib/Topology/ContinuousFunction/NonUnitalFunctionalCalculus.lean | 147 | 167 | theorem cfcₙHom_comp [UniqueNonUnitalContinuousFunctionalCalculus R A] (f : C(σₙ R a, R)₀)
(f' : C(σₙ R a, σₙ R (cfcₙHom ha f))₀)
(hff' : ∀ x, f x = f' x) (g : C(σₙ R (cfcₙHom ha f), R)₀) :
cfcₙHom ha (g.comp f') = cfcₙHom (cfcₙHom_predicate ha f) g := by |
let ψ : C(σₙ R (cfcₙHom ha f), R)₀ →⋆ₙₐ[R] C(σₙ R a, R)₀ :=
{ toFun := (ContinuousMapZero.comp · f')
map_smul' := fun _ _ ↦ rfl
map_add' := fun _ _ ↦ rfl
map_mul' := fun _ _ ↦ rfl
map_zero' := rfl
map_star' := fun _ ↦ rfl }
let φ : C(σₙ R (cfcₙHom ha f), R)₀ →⋆ₙₐ[R] A := (cfcₙHom ha).comp ψ
suffices cfcₙHom (cfcₙHom_predicate ha f) = φ from DFunLike.congr_fun this.symm g
refine cfcₙHom_eq_of_continuous_of_map_id (cfcₙHom_predicate ha f) φ ?_ ?_
· refine (cfcₙHom_closedEmbedding ha).continuous.comp <| continuous_induced_rng.mpr ?_
exact f'.toContinuousMap.continuous_comp_left.comp continuous_induced_dom
· simp only [φ, ψ, NonUnitalStarAlgHom.comp_apply, NonUnitalStarAlgHom.coe_mk',
NonUnitalAlgHom.coe_mk]
congr
ext x
simp [hff']
| 2,018 |
import Mathlib.Analysis.Calculus.LocalExtr.Rolle
import Mathlib.Analysis.Calculus.Deriv.Polynomial
import Mathlib.Topology.Algebra.Polynomial
#align_import analysis.calculus.local_extr from "leanprover-community/mathlib"@"3bce8d800a6f2b8f63fe1e588fd76a9ff4adcebe"
namespace Polynomial
| Mathlib/Analysis/Calculus/LocalExtr/Polynomial.lean | 36 | 46 | theorem card_roots_toFinset_le_card_roots_derivative_diff_roots_succ (p : ℝ[X]) :
p.roots.toFinset.card ≤ (p.derivative.roots.toFinset \ p.roots.toFinset).card + 1 := by |
rcases eq_or_ne (derivative p) 0 with hp' | hp'
· rw [eq_C_of_derivative_eq_zero hp', roots_C, Multiset.toFinset_zero, Finset.card_empty]
exact zero_le _
have hp : p ≠ 0 := ne_of_apply_ne derivative (by rwa [derivative_zero])
refine Finset.card_le_diff_of_interleaved fun x hx y hy hxy hxy' => ?_
rw [Multiset.mem_toFinset, mem_roots hp] at hx hy
obtain ⟨z, hz1, hz2⟩ := exists_deriv_eq_zero hxy p.continuousOn (hx.trans hy.symm)
refine ⟨z, ?_, hz1⟩
rwa [Multiset.mem_toFinset, mem_roots hp', IsRoot, ← p.deriv]
| 2,019 |
import Mathlib.Analysis.Calculus.LocalExtr.Rolle
import Mathlib.Analysis.Calculus.Deriv.Polynomial
import Mathlib.Topology.Algebra.Polynomial
#align_import analysis.calculus.local_extr from "leanprover-community/mathlib"@"3bce8d800a6f2b8f63fe1e588fd76a9ff4adcebe"
namespace Polynomial
theorem card_roots_toFinset_le_card_roots_derivative_diff_roots_succ (p : ℝ[X]) :
p.roots.toFinset.card ≤ (p.derivative.roots.toFinset \ p.roots.toFinset).card + 1 := by
rcases eq_or_ne (derivative p) 0 with hp' | hp'
· rw [eq_C_of_derivative_eq_zero hp', roots_C, Multiset.toFinset_zero, Finset.card_empty]
exact zero_le _
have hp : p ≠ 0 := ne_of_apply_ne derivative (by rwa [derivative_zero])
refine Finset.card_le_diff_of_interleaved fun x hx y hy hxy hxy' => ?_
rw [Multiset.mem_toFinset, mem_roots hp] at hx hy
obtain ⟨z, hz1, hz2⟩ := exists_deriv_eq_zero hxy p.continuousOn (hx.trans hy.symm)
refine ⟨z, ?_, hz1⟩
rwa [Multiset.mem_toFinset, mem_roots hp', IsRoot, ← p.deriv]
#align polynomial.card_roots_to_finset_le_card_roots_derivative_diff_roots_succ Polynomial.card_roots_toFinset_le_card_roots_derivative_diff_roots_succ
theorem card_roots_toFinset_le_derivative (p : ℝ[X]) :
p.roots.toFinset.card ≤ p.derivative.roots.toFinset.card + 1 :=
p.card_roots_toFinset_le_card_roots_derivative_diff_roots_succ.trans <|
add_le_add_right (Finset.card_mono Finset.sdiff_subset) _
#align polynomial.card_roots_to_finset_le_derivative Polynomial.card_roots_toFinset_le_derivative
| Mathlib/Analysis/Calculus/LocalExtr/Polynomial.lean | 59 | 86 | theorem card_roots_le_derivative (p : ℝ[X]) :
Multiset.card p.roots ≤ Multiset.card (derivative p).roots + 1 :=
calc
Multiset.card p.roots = ∑ x ∈ p.roots.toFinset, p.roots.count x :=
(Multiset.toFinset_sum_count_eq _).symm
_ = ∑ x ∈ p.roots.toFinset, (p.roots.count x - 1 + 1) :=
(Eq.symm <| Finset.sum_congr rfl fun x hx => tsub_add_cancel_of_le <|
Nat.succ_le_iff.2 <| Multiset.count_pos.2 <| Multiset.mem_toFinset.1 hx)
_ = (∑ x ∈ p.roots.toFinset, (p.rootMultiplicity x - 1)) + p.roots.toFinset.card := by |
simp only [Finset.sum_add_distrib, Finset.card_eq_sum_ones, count_roots]
_ ≤ (∑ x ∈ p.roots.toFinset, p.derivative.rootMultiplicity x) +
((p.derivative.roots.toFinset \ p.roots.toFinset).card + 1) :=
(add_le_add
(Finset.sum_le_sum fun x _ => rootMultiplicity_sub_one_le_derivative_rootMultiplicity _ _)
p.card_roots_toFinset_le_card_roots_derivative_diff_roots_succ)
_ ≤ (∑ x ∈ p.roots.toFinset, p.derivative.roots.count x) +
((∑ x ∈ p.derivative.roots.toFinset \ p.roots.toFinset,
p.derivative.roots.count x) + 1) := by
simp only [← count_roots]
refine add_le_add_left (add_le_add_right ((Finset.card_eq_sum_ones _).trans_le ?_) _) _
refine Finset.sum_le_sum fun x hx => Nat.succ_le_iff.2 <| ?_
rw [Multiset.count_pos, ← Multiset.mem_toFinset]
exact (Finset.mem_sdiff.1 hx).1
_ = Multiset.card (derivative p).roots + 1 := by
rw [← add_assoc, ← Finset.sum_union Finset.disjoint_sdiff, Finset.union_sdiff_self_eq_union, ←
Multiset.toFinset_sum_count_eq, ← Finset.sum_subset Finset.subset_union_right]
intro x _ hx₂
simpa only [Multiset.mem_toFinset, Multiset.count_eq_zero] using hx₂
| 2,019 |
import Mathlib.Analysis.Calculus.LocalExtr.Rolle
import Mathlib.Analysis.Calculus.Deriv.Polynomial
import Mathlib.Topology.Algebra.Polynomial
#align_import analysis.calculus.local_extr from "leanprover-community/mathlib"@"3bce8d800a6f2b8f63fe1e588fd76a9ff4adcebe"
namespace Polynomial
theorem card_roots_toFinset_le_card_roots_derivative_diff_roots_succ (p : ℝ[X]) :
p.roots.toFinset.card ≤ (p.derivative.roots.toFinset \ p.roots.toFinset).card + 1 := by
rcases eq_or_ne (derivative p) 0 with hp' | hp'
· rw [eq_C_of_derivative_eq_zero hp', roots_C, Multiset.toFinset_zero, Finset.card_empty]
exact zero_le _
have hp : p ≠ 0 := ne_of_apply_ne derivative (by rwa [derivative_zero])
refine Finset.card_le_diff_of_interleaved fun x hx y hy hxy hxy' => ?_
rw [Multiset.mem_toFinset, mem_roots hp] at hx hy
obtain ⟨z, hz1, hz2⟩ := exists_deriv_eq_zero hxy p.continuousOn (hx.trans hy.symm)
refine ⟨z, ?_, hz1⟩
rwa [Multiset.mem_toFinset, mem_roots hp', IsRoot, ← p.deriv]
#align polynomial.card_roots_to_finset_le_card_roots_derivative_diff_roots_succ Polynomial.card_roots_toFinset_le_card_roots_derivative_diff_roots_succ
theorem card_roots_toFinset_le_derivative (p : ℝ[X]) :
p.roots.toFinset.card ≤ p.derivative.roots.toFinset.card + 1 :=
p.card_roots_toFinset_le_card_roots_derivative_diff_roots_succ.trans <|
add_le_add_right (Finset.card_mono Finset.sdiff_subset) _
#align polynomial.card_roots_to_finset_le_derivative Polynomial.card_roots_toFinset_le_derivative
theorem card_roots_le_derivative (p : ℝ[X]) :
Multiset.card p.roots ≤ Multiset.card (derivative p).roots + 1 :=
calc
Multiset.card p.roots = ∑ x ∈ p.roots.toFinset, p.roots.count x :=
(Multiset.toFinset_sum_count_eq _).symm
_ = ∑ x ∈ p.roots.toFinset, (p.roots.count x - 1 + 1) :=
(Eq.symm <| Finset.sum_congr rfl fun x hx => tsub_add_cancel_of_le <|
Nat.succ_le_iff.2 <| Multiset.count_pos.2 <| Multiset.mem_toFinset.1 hx)
_ = (∑ x ∈ p.roots.toFinset, (p.rootMultiplicity x - 1)) + p.roots.toFinset.card := by
simp only [Finset.sum_add_distrib, Finset.card_eq_sum_ones, count_roots]
_ ≤ (∑ x ∈ p.roots.toFinset, p.derivative.rootMultiplicity x) +
((p.derivative.roots.toFinset \ p.roots.toFinset).card + 1) :=
(add_le_add
(Finset.sum_le_sum fun x _ => rootMultiplicity_sub_one_le_derivative_rootMultiplicity _ _)
p.card_roots_toFinset_le_card_roots_derivative_diff_roots_succ)
_ ≤ (∑ x ∈ p.roots.toFinset, p.derivative.roots.count x) +
((∑ x ∈ p.derivative.roots.toFinset \ p.roots.toFinset,
p.derivative.roots.count x) + 1) := by
simp only [← count_roots]
refine add_le_add_left (add_le_add_right ((Finset.card_eq_sum_ones _).trans_le ?_) _) _
refine Finset.sum_le_sum fun x hx => Nat.succ_le_iff.2 <| ?_
rw [Multiset.count_pos, ← Multiset.mem_toFinset]
exact (Finset.mem_sdiff.1 hx).1
_ = Multiset.card (derivative p).roots + 1 := by
rw [← add_assoc, ← Finset.sum_union Finset.disjoint_sdiff, Finset.union_sdiff_self_eq_union, ←
Multiset.toFinset_sum_count_eq, ← Finset.sum_subset Finset.subset_union_right]
intro x _ hx₂
simpa only [Multiset.mem_toFinset, Multiset.count_eq_zero] using hx₂
#align polynomial.card_roots_le_derivative Polynomial.card_roots_le_derivative
| Mathlib/Analysis/Calculus/LocalExtr/Polynomial.lean | 91 | 94 | theorem card_rootSet_le_derivative {F : Type*} [CommRing F] [Algebra F ℝ] (p : F[X]) :
Fintype.card (p.rootSet ℝ) ≤ Fintype.card (p.derivative.rootSet ℝ) + 1 := by |
simpa only [rootSet_def, Finset.coe_sort_coe, Fintype.card_coe, derivative_map] using
card_roots_toFinset_le_derivative (p.map (algebraMap F ℝ))
| 2,019 |
import Mathlib.Algebra.GroupWithZero.NonZeroDivisors
import Mathlib.Algebra.Polynomial.Lifts
import Mathlib.GroupTheory.MonoidLocalization
import Mathlib.RingTheory.Algebraic
import Mathlib.RingTheory.Ideal.LocalRing
import Mathlib.RingTheory.IntegralClosure
import Mathlib.RingTheory.Localization.FractionRing
import Mathlib.RingTheory.Localization.Integer
#align_import ring_theory.localization.integral from "leanprover-community/mathlib"@"831c494092374cfe9f50591ed0ac81a25efc5b86"
variable {R : Type*} [CommRing R] (M : Submonoid R) {S : Type*} [CommRing S]
variable [Algebra R S] {P : Type*} [CommRing P]
open Polynomial
namespace IsLocalization
section IntegerNormalization
open Polynomial
variable [IsLocalization M S]
open scoped Classical
noncomputable def coeffIntegerNormalization (p : S[X]) (i : ℕ) : R :=
if hi : i ∈ p.support then
Classical.choose
(Classical.choose_spec (exist_integer_multiples_of_finset M (p.support.image p.coeff))
(p.coeff i) (Finset.mem_image.mpr ⟨i, hi, rfl⟩))
else 0
#align is_localization.coeff_integer_normalization IsLocalization.coeffIntegerNormalization
| Mathlib/RingTheory/Localization/Integral.lean | 55 | 58 | theorem coeffIntegerNormalization_of_not_mem_support (p : S[X]) (i : ℕ) (h : coeff p i = 0) :
coeffIntegerNormalization M p i = 0 := by |
simp only [coeffIntegerNormalization, h, mem_support_iff, eq_self_iff_true, not_true, Ne,
dif_neg, not_false_iff]
| 2,020 |
import Mathlib.Algebra.GroupWithZero.NonZeroDivisors
import Mathlib.Algebra.Polynomial.Lifts
import Mathlib.GroupTheory.MonoidLocalization
import Mathlib.RingTheory.Algebraic
import Mathlib.RingTheory.Ideal.LocalRing
import Mathlib.RingTheory.IntegralClosure
import Mathlib.RingTheory.Localization.FractionRing
import Mathlib.RingTheory.Localization.Integer
#align_import ring_theory.localization.integral from "leanprover-community/mathlib"@"831c494092374cfe9f50591ed0ac81a25efc5b86"
variable {R : Type*} [CommRing R] (M : Submonoid R) {S : Type*} [CommRing S]
variable [Algebra R S] {P : Type*} [CommRing P]
open Polynomial
namespace IsLocalization
section IntegerNormalization
open Polynomial
variable [IsLocalization M S]
open scoped Classical
noncomputable def coeffIntegerNormalization (p : S[X]) (i : ℕ) : R :=
if hi : i ∈ p.support then
Classical.choose
(Classical.choose_spec (exist_integer_multiples_of_finset M (p.support.image p.coeff))
(p.coeff i) (Finset.mem_image.mpr ⟨i, hi, rfl⟩))
else 0
#align is_localization.coeff_integer_normalization IsLocalization.coeffIntegerNormalization
theorem coeffIntegerNormalization_of_not_mem_support (p : S[X]) (i : ℕ) (h : coeff p i = 0) :
coeffIntegerNormalization M p i = 0 := by
simp only [coeffIntegerNormalization, h, mem_support_iff, eq_self_iff_true, not_true, Ne,
dif_neg, not_false_iff]
#align is_localization.coeff_integer_normalization_of_not_mem_support IsLocalization.coeffIntegerNormalization_of_not_mem_support
| Mathlib/RingTheory/Localization/Integral.lean | 61 | 64 | theorem coeffIntegerNormalization_mem_support (p : S[X]) (i : ℕ)
(h : coeffIntegerNormalization M p i ≠ 0) : i ∈ p.support := by |
contrapose h
rw [Ne, Classical.not_not, coeffIntegerNormalization, dif_neg h]
| 2,020 |
import Mathlib.Algebra.GroupWithZero.NonZeroDivisors
import Mathlib.Algebra.Polynomial.Lifts
import Mathlib.GroupTheory.MonoidLocalization
import Mathlib.RingTheory.Algebraic
import Mathlib.RingTheory.Ideal.LocalRing
import Mathlib.RingTheory.IntegralClosure
import Mathlib.RingTheory.Localization.FractionRing
import Mathlib.RingTheory.Localization.Integer
#align_import ring_theory.localization.integral from "leanprover-community/mathlib"@"831c494092374cfe9f50591ed0ac81a25efc5b86"
variable {R : Type*} [CommRing R] (M : Submonoid R) {S : Type*} [CommRing S]
variable [Algebra R S] {P : Type*} [CommRing P]
open Polynomial
namespace IsLocalization
section IntegerNormalization
open Polynomial
variable [IsLocalization M S]
open scoped Classical
noncomputable def coeffIntegerNormalization (p : S[X]) (i : ℕ) : R :=
if hi : i ∈ p.support then
Classical.choose
(Classical.choose_spec (exist_integer_multiples_of_finset M (p.support.image p.coeff))
(p.coeff i) (Finset.mem_image.mpr ⟨i, hi, rfl⟩))
else 0
#align is_localization.coeff_integer_normalization IsLocalization.coeffIntegerNormalization
theorem coeffIntegerNormalization_of_not_mem_support (p : S[X]) (i : ℕ) (h : coeff p i = 0) :
coeffIntegerNormalization M p i = 0 := by
simp only [coeffIntegerNormalization, h, mem_support_iff, eq_self_iff_true, not_true, Ne,
dif_neg, not_false_iff]
#align is_localization.coeff_integer_normalization_of_not_mem_support IsLocalization.coeffIntegerNormalization_of_not_mem_support
theorem coeffIntegerNormalization_mem_support (p : S[X]) (i : ℕ)
(h : coeffIntegerNormalization M p i ≠ 0) : i ∈ p.support := by
contrapose h
rw [Ne, Classical.not_not, coeffIntegerNormalization, dif_neg h]
#align is_localization.coeff_integer_normalization_mem_support IsLocalization.coeffIntegerNormalization_mem_support
noncomputable def integerNormalization (p : S[X]) : R[X] :=
∑ i ∈ p.support, monomial i (coeffIntegerNormalization M p i)
#align is_localization.integer_normalization IsLocalization.integerNormalization
@[simp]
| Mathlib/RingTheory/Localization/Integral.lean | 74 | 77 | theorem integerNormalization_coeff (p : S[X]) (i : ℕ) :
(integerNormalization M p).coeff i = coeffIntegerNormalization M p i := by |
simp (config := { contextual := true }) [integerNormalization, coeff_monomial,
coeffIntegerNormalization_of_not_mem_support]
| 2,020 |
import Mathlib.Algebra.GroupWithZero.NonZeroDivisors
import Mathlib.Algebra.Polynomial.Lifts
import Mathlib.GroupTheory.MonoidLocalization
import Mathlib.RingTheory.Algebraic
import Mathlib.RingTheory.Ideal.LocalRing
import Mathlib.RingTheory.IntegralClosure
import Mathlib.RingTheory.Localization.FractionRing
import Mathlib.RingTheory.Localization.Integer
#align_import ring_theory.localization.integral from "leanprover-community/mathlib"@"831c494092374cfe9f50591ed0ac81a25efc5b86"
variable {R : Type*} [CommRing R] (M : Submonoid R) {S : Type*} [CommRing S]
variable [Algebra R S] {P : Type*} [CommRing P]
open Polynomial
namespace IsLocalization
section IntegerNormalization
open Polynomial
variable [IsLocalization M S]
open scoped Classical
noncomputable def coeffIntegerNormalization (p : S[X]) (i : ℕ) : R :=
if hi : i ∈ p.support then
Classical.choose
(Classical.choose_spec (exist_integer_multiples_of_finset M (p.support.image p.coeff))
(p.coeff i) (Finset.mem_image.mpr ⟨i, hi, rfl⟩))
else 0
#align is_localization.coeff_integer_normalization IsLocalization.coeffIntegerNormalization
theorem coeffIntegerNormalization_of_not_mem_support (p : S[X]) (i : ℕ) (h : coeff p i = 0) :
coeffIntegerNormalization M p i = 0 := by
simp only [coeffIntegerNormalization, h, mem_support_iff, eq_self_iff_true, not_true, Ne,
dif_neg, not_false_iff]
#align is_localization.coeff_integer_normalization_of_not_mem_support IsLocalization.coeffIntegerNormalization_of_not_mem_support
theorem coeffIntegerNormalization_mem_support (p : S[X]) (i : ℕ)
(h : coeffIntegerNormalization M p i ≠ 0) : i ∈ p.support := by
contrapose h
rw [Ne, Classical.not_not, coeffIntegerNormalization, dif_neg h]
#align is_localization.coeff_integer_normalization_mem_support IsLocalization.coeffIntegerNormalization_mem_support
noncomputable def integerNormalization (p : S[X]) : R[X] :=
∑ i ∈ p.support, monomial i (coeffIntegerNormalization M p i)
#align is_localization.integer_normalization IsLocalization.integerNormalization
@[simp]
theorem integerNormalization_coeff (p : S[X]) (i : ℕ) :
(integerNormalization M p).coeff i = coeffIntegerNormalization M p i := by
simp (config := { contextual := true }) [integerNormalization, coeff_monomial,
coeffIntegerNormalization_of_not_mem_support]
#align is_localization.integer_normalization_coeff IsLocalization.integerNormalization_coeff
| Mathlib/RingTheory/Localization/Integral.lean | 80 | 90 | theorem integerNormalization_spec (p : S[X]) :
∃ b : M, ∀ i, algebraMap R S ((integerNormalization M p).coeff i) = (b : R) • p.coeff i := by |
use Classical.choose (exist_integer_multiples_of_finset M (p.support.image p.coeff))
intro i
rw [integerNormalization_coeff, coeffIntegerNormalization]
split_ifs with hi
· exact
Classical.choose_spec
(Classical.choose_spec (exist_integer_multiples_of_finset M (p.support.image p.coeff))
(p.coeff i) (Finset.mem_image.mpr ⟨i, hi, rfl⟩))
· rw [RingHom.map_zero, not_mem_support_iff.mp hi, smul_zero]
| 2,020 |
import Mathlib.Algebra.GroupWithZero.NonZeroDivisors
import Mathlib.Algebra.Polynomial.Lifts
import Mathlib.GroupTheory.MonoidLocalization
import Mathlib.RingTheory.Algebraic
import Mathlib.RingTheory.Ideal.LocalRing
import Mathlib.RingTheory.IntegralClosure
import Mathlib.RingTheory.Localization.FractionRing
import Mathlib.RingTheory.Localization.Integer
#align_import ring_theory.localization.integral from "leanprover-community/mathlib"@"831c494092374cfe9f50591ed0ac81a25efc5b86"
variable {R : Type*} [CommRing R] (M : Submonoid R) {S : Type*} [CommRing S]
variable [Algebra R S] {P : Type*} [CommRing P]
open Polynomial
namespace IsLocalization
section IntegerNormalization
open Polynomial
variable [IsLocalization M S]
open scoped Classical
noncomputable def coeffIntegerNormalization (p : S[X]) (i : ℕ) : R :=
if hi : i ∈ p.support then
Classical.choose
(Classical.choose_spec (exist_integer_multiples_of_finset M (p.support.image p.coeff))
(p.coeff i) (Finset.mem_image.mpr ⟨i, hi, rfl⟩))
else 0
#align is_localization.coeff_integer_normalization IsLocalization.coeffIntegerNormalization
theorem coeffIntegerNormalization_of_not_mem_support (p : S[X]) (i : ℕ) (h : coeff p i = 0) :
coeffIntegerNormalization M p i = 0 := by
simp only [coeffIntegerNormalization, h, mem_support_iff, eq_self_iff_true, not_true, Ne,
dif_neg, not_false_iff]
#align is_localization.coeff_integer_normalization_of_not_mem_support IsLocalization.coeffIntegerNormalization_of_not_mem_support
theorem coeffIntegerNormalization_mem_support (p : S[X]) (i : ℕ)
(h : coeffIntegerNormalization M p i ≠ 0) : i ∈ p.support := by
contrapose h
rw [Ne, Classical.not_not, coeffIntegerNormalization, dif_neg h]
#align is_localization.coeff_integer_normalization_mem_support IsLocalization.coeffIntegerNormalization_mem_support
noncomputable def integerNormalization (p : S[X]) : R[X] :=
∑ i ∈ p.support, monomial i (coeffIntegerNormalization M p i)
#align is_localization.integer_normalization IsLocalization.integerNormalization
@[simp]
theorem integerNormalization_coeff (p : S[X]) (i : ℕ) :
(integerNormalization M p).coeff i = coeffIntegerNormalization M p i := by
simp (config := { contextual := true }) [integerNormalization, coeff_monomial,
coeffIntegerNormalization_of_not_mem_support]
#align is_localization.integer_normalization_coeff IsLocalization.integerNormalization_coeff
theorem integerNormalization_spec (p : S[X]) :
∃ b : M, ∀ i, algebraMap R S ((integerNormalization M p).coeff i) = (b : R) • p.coeff i := by
use Classical.choose (exist_integer_multiples_of_finset M (p.support.image p.coeff))
intro i
rw [integerNormalization_coeff, coeffIntegerNormalization]
split_ifs with hi
· exact
Classical.choose_spec
(Classical.choose_spec (exist_integer_multiples_of_finset M (p.support.image p.coeff))
(p.coeff i) (Finset.mem_image.mpr ⟨i, hi, rfl⟩))
· rw [RingHom.map_zero, not_mem_support_iff.mp hi, smul_zero]
-- Porting note: was `convert (smul_zero _).symm, ...`
#align is_localization.integer_normalization_spec IsLocalization.integerNormalization_spec
theorem integerNormalization_map_to_map (p : S[X]) :
∃ b : M, (integerNormalization M p).map (algebraMap R S) = (b : R) • p :=
let ⟨b, hb⟩ := integerNormalization_spec M p
⟨b,
Polynomial.ext fun i => by
rw [coeff_map, coeff_smul]
exact hb i⟩
#align is_localization.integer_normalization_map_to_map IsLocalization.integerNormalization_map_to_map
variable {R' : Type*} [CommRing R']
theorem integerNormalization_eval₂_eq_zero (g : S →+* R') (p : S[X]) {x : R'}
(hx : eval₂ g x p = 0) : eval₂ (g.comp (algebraMap R S)) x (integerNormalization M p) = 0 :=
let ⟨b, hb⟩ := integerNormalization_map_to_map M p
_root_.trans (eval₂_map (algebraMap R S) g x).symm
(by rw [hb, ← IsScalarTower.algebraMap_smul S (b : R) p, eval₂_smul, hx, mul_zero])
#align is_localization.integer_normalization_eval₂_eq_zero IsLocalization.integerNormalization_eval₂_eq_zero
| Mathlib/RingTheory/Localization/Integral.lean | 112 | 115 | theorem integerNormalization_aeval_eq_zero [Algebra R R'] [Algebra S R'] [IsScalarTower R S R']
(p : S[X]) {x : R'} (hx : aeval x p = 0) : aeval x (integerNormalization M p) = 0 := by |
rw [aeval_def, IsScalarTower.algebraMap_eq R S R',
integerNormalization_eval₂_eq_zero _ (algebraMap _ _) _ hx]
| 2,020 |
import Mathlib.Algebra.GroupWithZero.NonZeroDivisors
import Mathlib.Algebra.Polynomial.Lifts
import Mathlib.GroupTheory.MonoidLocalization
import Mathlib.RingTheory.Algebraic
import Mathlib.RingTheory.Ideal.LocalRing
import Mathlib.RingTheory.IntegralClosure
import Mathlib.RingTheory.Localization.FractionRing
import Mathlib.RingTheory.Localization.Integer
#align_import ring_theory.localization.integral from "leanprover-community/mathlib"@"831c494092374cfe9f50591ed0ac81a25efc5b86"
variable {R : Type*} [CommRing R] (M : Submonoid R) {S : Type*} [CommRing S]
variable [Algebra R S] {P : Type*} [CommRing P]
open Polynomial
namespace IsLocalization
open IsLocalization
section IsIntegral
variable {Rₘ Sₘ : Type*} [CommRing Rₘ] [CommRing Sₘ]
variable [Algebra R Rₘ] [IsLocalization M Rₘ]
variable [Algebra S Sₘ] [IsLocalization (Algebra.algebraMapSubmonoid S M) Sₘ]
variable {M}
open Polynomial
| Mathlib/RingTheory/Localization/Integral.lean | 185 | 201 | theorem RingHom.isIntegralElem_localization_at_leadingCoeff {R S : Type*} [CommRing R] [CommRing S]
(f : R →+* S) (x : S) (p : R[X]) (hf : p.eval₂ f x = 0) (M : Submonoid R)
(hM : p.leadingCoeff ∈ M) {Rₘ Sₘ : Type*} [CommRing Rₘ] [CommRing Sₘ] [Algebra R Rₘ]
[IsLocalization M Rₘ] [Algebra S Sₘ] [IsLocalization (M.map f : Submonoid S) Sₘ] :
(map Sₘ f M.le_comap_map : Rₘ →+* _).IsIntegralElem (algebraMap S Sₘ x) := by |
by_cases triv : (1 : Rₘ) = 0
· exact ⟨0, ⟨_root_.trans leadingCoeff_zero triv.symm, eval₂_zero _ _⟩⟩
haveI : Nontrivial Rₘ := nontrivial_of_ne 1 0 triv
obtain ⟨b, hb⟩ := isUnit_iff_exists_inv.mp (map_units Rₘ ⟨p.leadingCoeff, hM⟩)
refine ⟨p.map (algebraMap R Rₘ) * C b, ⟨?_, ?_⟩⟩
· refine monic_mul_C_of_leadingCoeff_mul_eq_one ?_
rwa [leadingCoeff_map_of_leadingCoeff_ne_zero (algebraMap R Rₘ)]
refine fun hfp => zero_ne_one
(_root_.trans (zero_mul b).symm (hfp ▸ hb) : (0 : Rₘ) = 1)
· refine eval₂_mul_eq_zero_of_left _ _ _ ?_
erw [eval₂_map, IsLocalization.map_comp, ← hom_eval₂ _ f (algebraMap S Sₘ) x]
exact _root_.trans (congr_arg (algebraMap S Sₘ) hf) (RingHom.map_zero _)
| 2,020 |
import Mathlib.RingTheory.IntegralClosure
import Mathlib.RingTheory.Localization.Integral
#align_import ring_theory.integrally_closed from "leanprover-community/mathlib"@"d35b4ff446f1421bd551fafa4b8efd98ac3ac408"
open scoped nonZeroDivisors Polynomial
open Polynomial
abbrev IsIntegrallyClosedIn (R A : Type*) [CommRing R] [CommRing A] [Algebra R A] :=
IsIntegralClosure R R A
abbrev IsIntegrallyClosed (R : Type*) [CommRing R] := IsIntegrallyClosedIn R (FractionRing R)
#align is_integrally_closed IsIntegrallyClosed
section Iff
variable {R : Type*} [CommRing R]
variable {A B : Type*} [CommRing A] [CommRing B] [Algebra R A] [Algebra R B]
| Mathlib/RingTheory/IntegrallyClosed.lean | 80 | 90 | theorem AlgHom.isIntegrallyClosedIn (f : A →ₐ[R] B) (hf : Function.Injective f) :
IsIntegrallyClosedIn R B → IsIntegrallyClosedIn R A := by |
rintro ⟨inj, cl⟩
refine ⟨Function.Injective.of_comp (f := f) ?_, fun hx => ?_, ?_⟩
· convert inj
aesop
· obtain ⟨y, fx_eq⟩ := cl.mp ((isIntegral_algHom_iff f hf).mpr hx)
aesop
· rintro ⟨y, rfl⟩
apply (isIntegral_algHom_iff f hf).mp
aesop
| 2,021 |
import Mathlib.RingTheory.IntegralClosure
import Mathlib.RingTheory.Localization.Integral
#align_import ring_theory.integrally_closed from "leanprover-community/mathlib"@"d35b4ff446f1421bd551fafa4b8efd98ac3ac408"
open scoped nonZeroDivisors Polynomial
open Polynomial
abbrev IsIntegrallyClosedIn (R A : Type*) [CommRing R] [CommRing A] [Algebra R A] :=
IsIntegralClosure R R A
abbrev IsIntegrallyClosed (R : Type*) [CommRing R] := IsIntegrallyClosedIn R (FractionRing R)
#align is_integrally_closed IsIntegrallyClosed
section Iff
variable {R : Type*} [CommRing R]
variable {A B : Type*} [CommRing A] [CommRing B] [Algebra R A] [Algebra R B]
theorem AlgHom.isIntegrallyClosedIn (f : A →ₐ[R] B) (hf : Function.Injective f) :
IsIntegrallyClosedIn R B → IsIntegrallyClosedIn R A := by
rintro ⟨inj, cl⟩
refine ⟨Function.Injective.of_comp (f := f) ?_, fun hx => ?_, ?_⟩
· convert inj
aesop
· obtain ⟨y, fx_eq⟩ := cl.mp ((isIntegral_algHom_iff f hf).mpr hx)
aesop
· rintro ⟨y, rfl⟩
apply (isIntegral_algHom_iff f hf).mp
aesop
theorem AlgEquiv.isIntegrallyClosedIn (e : A ≃ₐ[R] B) :
IsIntegrallyClosedIn R A ↔ IsIntegrallyClosedIn R B :=
⟨AlgHom.isIntegrallyClosedIn e.symm e.symm.injective, AlgHom.isIntegrallyClosedIn e e.injective⟩
variable (K : Type*) [CommRing K] [Algebra R K] [IsFractionRing R K]
theorem isIntegrallyClosed_iff_isIntegrallyClosedIn :
IsIntegrallyClosed R ↔ IsIntegrallyClosedIn R K :=
(IsLocalization.algEquiv R⁰ _ _).isIntegrallyClosedIn
theorem isIntegrallyClosed_iff_isIntegralClosure : IsIntegrallyClosed R ↔ IsIntegralClosure R R K :=
isIntegrallyClosed_iff_isIntegrallyClosedIn K
#align is_integrally_closed_iff_is_integral_closure isIntegrallyClosed_iff_isIntegralClosure
| Mathlib/RingTheory/IntegrallyClosed.lean | 110 | 120 | theorem isIntegrallyClosedIn_iff {R A : Type*} [CommRing R] [CommRing A] [Algebra R A] :
IsIntegrallyClosedIn R A ↔
Function.Injective (algebraMap R A) ∧
∀ {x : A}, IsIntegral R x → ∃ y, algebraMap R A y = x := by |
constructor
· rintro ⟨_, cl⟩
aesop
· rintro ⟨inj, cl⟩
refine ⟨inj, by aesop, ?_⟩
rintro ⟨y, rfl⟩
apply isIntegral_algebraMap
| 2,021 |
import Mathlib.RingTheory.IntegralClosure
import Mathlib.RingTheory.Localization.Integral
#align_import ring_theory.integrally_closed from "leanprover-community/mathlib"@"d35b4ff446f1421bd551fafa4b8efd98ac3ac408"
open scoped nonZeroDivisors Polynomial
open Polynomial
abbrev IsIntegrallyClosedIn (R A : Type*) [CommRing R] [CommRing A] [Algebra R A] :=
IsIntegralClosure R R A
abbrev IsIntegrallyClosed (R : Type*) [CommRing R] := IsIntegrallyClosedIn R (FractionRing R)
#align is_integrally_closed IsIntegrallyClosed
section Iff
variable {R : Type*} [CommRing R]
variable {A B : Type*} [CommRing A] [CommRing B] [Algebra R A] [Algebra R B]
theorem AlgHom.isIntegrallyClosedIn (f : A →ₐ[R] B) (hf : Function.Injective f) :
IsIntegrallyClosedIn R B → IsIntegrallyClosedIn R A := by
rintro ⟨inj, cl⟩
refine ⟨Function.Injective.of_comp (f := f) ?_, fun hx => ?_, ?_⟩
· convert inj
aesop
· obtain ⟨y, fx_eq⟩ := cl.mp ((isIntegral_algHom_iff f hf).mpr hx)
aesop
· rintro ⟨y, rfl⟩
apply (isIntegral_algHom_iff f hf).mp
aesop
theorem AlgEquiv.isIntegrallyClosedIn (e : A ≃ₐ[R] B) :
IsIntegrallyClosedIn R A ↔ IsIntegrallyClosedIn R B :=
⟨AlgHom.isIntegrallyClosedIn e.symm e.symm.injective, AlgHom.isIntegrallyClosedIn e e.injective⟩
variable (K : Type*) [CommRing K] [Algebra R K] [IsFractionRing R K]
theorem isIntegrallyClosed_iff_isIntegrallyClosedIn :
IsIntegrallyClosed R ↔ IsIntegrallyClosedIn R K :=
(IsLocalization.algEquiv R⁰ _ _).isIntegrallyClosedIn
theorem isIntegrallyClosed_iff_isIntegralClosure : IsIntegrallyClosed R ↔ IsIntegralClosure R R K :=
isIntegrallyClosed_iff_isIntegrallyClosedIn K
#align is_integrally_closed_iff_is_integral_closure isIntegrallyClosed_iff_isIntegralClosure
theorem isIntegrallyClosedIn_iff {R A : Type*} [CommRing R] [CommRing A] [Algebra R A] :
IsIntegrallyClosedIn R A ↔
Function.Injective (algebraMap R A) ∧
∀ {x : A}, IsIntegral R x → ∃ y, algebraMap R A y = x := by
constructor
· rintro ⟨_, cl⟩
aesop
· rintro ⟨inj, cl⟩
refine ⟨inj, by aesop, ?_⟩
rintro ⟨y, rfl⟩
apply isIntegral_algebraMap
| Mathlib/RingTheory/IntegrallyClosed.lean | 124 | 127 | theorem isIntegrallyClosed_iff :
IsIntegrallyClosed R ↔ ∀ {x : K}, IsIntegral R x → ∃ y, algebraMap R K y = x := by |
simp [isIntegrallyClosed_iff_isIntegrallyClosedIn K, isIntegrallyClosedIn_iff,
IsFractionRing.injective R K]
| 2,021 |
import Mathlib.RingTheory.IntegralClosure
import Mathlib.RingTheory.Localization.Integral
#align_import ring_theory.integrally_closed from "leanprover-community/mathlib"@"d35b4ff446f1421bd551fafa4b8efd98ac3ac408"
open scoped nonZeroDivisors Polynomial
open Polynomial
abbrev IsIntegrallyClosedIn (R A : Type*) [CommRing R] [CommRing A] [Algebra R A] :=
IsIntegralClosure R R A
abbrev IsIntegrallyClosed (R : Type*) [CommRing R] := IsIntegrallyClosedIn R (FractionRing R)
#align is_integrally_closed IsIntegrallyClosed
namespace IsIntegrallyClosedIn
variable {R A : Type*} [CommRing R] [CommRing A] [Algebra R A] [iic : IsIntegrallyClosedIn R A]
theorem algebraMap_eq_of_integral {x : A} : IsIntegral R x → ∃ y : R, algebraMap R A y = x :=
IsIntegralClosure.isIntegral_iff.mp
theorem isIntegral_iff {x : A} : IsIntegral R x ↔ ∃ y : R, algebraMap R A y = x :=
IsIntegralClosure.isIntegral_iff
theorem exists_algebraMap_eq_of_isIntegral_pow {x : A} {n : ℕ} (hn : 0 < n)
(hx : IsIntegral R <| x ^ n) : ∃ y : R, algebraMap R A y = x :=
isIntegral_iff.mp <| hx.of_pow hn
theorem exists_algebraMap_eq_of_pow_mem_subalgebra {A : Type*} [CommRing A] [Algebra R A]
{S : Subalgebra R A} [IsIntegrallyClosedIn S A] {x : A} {n : ℕ} (hn : 0 < n)
(hx : x ^ n ∈ S) : ∃ y : S, algebraMap S A y = x :=
exists_algebraMap_eq_of_isIntegral_pow hn <| isIntegral_iff.mpr ⟨⟨x ^ n, hx⟩, rfl⟩
variable (A)
| Mathlib/RingTheory/IntegrallyClosed.lean | 153 | 163 | theorem integralClosure_eq_bot_iff (hRA : Function.Injective (algebraMap R A)) :
integralClosure R A = ⊥ ↔ IsIntegrallyClosedIn R A := by |
refine eq_bot_iff.trans ?_
constructor
· intro h
refine ⟨ hRA, fun hx => Set.mem_range.mp (Algebra.mem_bot.mp (h hx)), ?_⟩
rintro ⟨y, rfl⟩
apply isIntegral_algebraMap
· intro h x hx
rw [Algebra.mem_bot, Set.mem_range]
exact isIntegral_iff.mp hx
| 2,021 |
import Mathlib.Algebra.GCDMonoid.Basic
import Mathlib.RingTheory.IntegrallyClosed
import Mathlib.RingTheory.Polynomial.Eisenstein.Basic
#align_import algebra.gcd_monoid.integrally_closed from "leanprover-community/mathlib"@"2032a878972d5672e7c27c957e7a6e297b044973"
open scoped Polynomial
variable {R A : Type*} [CommRing R] [IsDomain R] [CommRing A] [Algebra R A]
| Mathlib/Algebra/GCDMonoid/IntegrallyClosed.lean | 23 | 30 | theorem IsLocalization.surj_of_gcd_domain [GCDMonoid R] (M : Submonoid R) [IsLocalization M A]
(z : A) : ∃ a b : R, IsUnit (gcd a b) ∧ z * algebraMap R A b = algebraMap R A a := by |
obtain ⟨x, ⟨y, hy⟩, rfl⟩ := IsLocalization.mk'_surjective M z
obtain ⟨x', y', hx', hy', hu⟩ := extract_gcd x y
use x', y', hu
rw [mul_comm, IsLocalization.mul_mk'_eq_mk'_of_mul]
convert IsLocalization.mk'_mul_cancel_left (M := M) (S := A) _ _ using 2
rw [Subtype.coe_mk, hy', ← mul_comm y', mul_assoc]; conv_lhs => rw [hx']
| 2,022 |
import Mathlib.FieldTheory.SplittingField.Construction
import Mathlib.RingTheory.Int.Basic
import Mathlib.RingTheory.Localization.Integral
import Mathlib.RingTheory.IntegrallyClosed
#align_import ring_theory.polynomial.gauss_lemma from "leanprover-community/mathlib"@"e3f4be1fcb5376c4948d7f095bec45350bfb9d1a"
open scoped nonZeroDivisors Polynomial
variable {R : Type*} [CommRing R]
section IsIntegrallyClosed
open Polynomial
open integralClosure
open IsIntegrallyClosed
variable (K : Type*) [Field K] [Algebra R K]
| Mathlib/RingTheory/Polynomial/GaussLemma.lean | 54 | 70 | theorem integralClosure.mem_lifts_of_monic_of_dvd_map {f : R[X]} (hf : f.Monic) {g : K[X]}
(hg : g.Monic) (hd : g ∣ f.map (algebraMap R K)) :
g ∈ lifts (algebraMap (integralClosure R K) K) := by |
have := mem_lift_of_splits_of_roots_mem_range (integralClosure R g.SplittingField)
((splits_id_iff_splits _).2 <| SplittingField.splits g) (hg.map _) fun a ha =>
(SetLike.ext_iff.mp (integralClosure R g.SplittingField).range_algebraMap _).mpr <|
roots_mem_integralClosure hf ?_
· rw [lifts_iff_coeff_lifts, ← RingHom.coe_range, Subalgebra.range_algebraMap] at this
refine (lifts_iff_coeff_lifts _).2 fun n => ?_
rw [← RingHom.coe_range, Subalgebra.range_algebraMap]
obtain ⟨p, hp, he⟩ := SetLike.mem_coe.mp (this n); use p, hp
rw [IsScalarTower.algebraMap_eq R K, coeff_map, ← eval₂_map, eval₂_at_apply] at he
rw [eval₂_eq_eval_map]; apply (injective_iff_map_eq_zero _).1 _ _ he
apply RingHom.injective
rw [aroots_def, IsScalarTower.algebraMap_eq R K _, ← map_map]
refine Multiset.mem_of_le (roots.le_of_dvd ((hf.map _).map _).ne_zero ?_) ha
exact map_dvd (algebraMap K g.SplittingField) hd
| 2,023 |
import Mathlib.FieldTheory.SplittingField.Construction
import Mathlib.RingTheory.Int.Basic
import Mathlib.RingTheory.Localization.Integral
import Mathlib.RingTheory.IntegrallyClosed
#align_import ring_theory.polynomial.gauss_lemma from "leanprover-community/mathlib"@"e3f4be1fcb5376c4948d7f095bec45350bfb9d1a"
open scoped nonZeroDivisors Polynomial
variable {R : Type*} [CommRing R]
section IsIntegrallyClosed
open Polynomial
open integralClosure
open IsIntegrallyClosed
variable (K : Type*) [Field K] [Algebra R K]
theorem integralClosure.mem_lifts_of_monic_of_dvd_map {f : R[X]} (hf : f.Monic) {g : K[X]}
(hg : g.Monic) (hd : g ∣ f.map (algebraMap R K)) :
g ∈ lifts (algebraMap (integralClosure R K) K) := by
have := mem_lift_of_splits_of_roots_mem_range (integralClosure R g.SplittingField)
((splits_id_iff_splits _).2 <| SplittingField.splits g) (hg.map _) fun a ha =>
(SetLike.ext_iff.mp (integralClosure R g.SplittingField).range_algebraMap _).mpr <|
roots_mem_integralClosure hf ?_
· rw [lifts_iff_coeff_lifts, ← RingHom.coe_range, Subalgebra.range_algebraMap] at this
refine (lifts_iff_coeff_lifts _).2 fun n => ?_
rw [← RingHom.coe_range, Subalgebra.range_algebraMap]
obtain ⟨p, hp, he⟩ := SetLike.mem_coe.mp (this n); use p, hp
rw [IsScalarTower.algebraMap_eq R K, coeff_map, ← eval₂_map, eval₂_at_apply] at he
rw [eval₂_eq_eval_map]; apply (injective_iff_map_eq_zero _).1 _ _ he
apply RingHom.injective
rw [aroots_def, IsScalarTower.algebraMap_eq R K _, ← map_map]
refine Multiset.mem_of_le (roots.le_of_dvd ((hf.map _).map _).ne_zero ?_) ha
exact map_dvd (algebraMap K g.SplittingField) hd
#align integral_closure.mem_lifts_of_monic_of_dvd_map integralClosure.mem_lifts_of_monic_of_dvd_map
variable [IsDomain R] [IsFractionRing R K]
| Mathlib/RingTheory/Polynomial/GaussLemma.lean | 77 | 102 | theorem IsIntegrallyClosed.eq_map_mul_C_of_dvd [IsIntegrallyClosed R] {f : R[X]} (hf : f.Monic)
{g : K[X]} (hg : g ∣ f.map (algebraMap R K)) :
∃ g' : R[X], g'.map (algebraMap R K) * (C <| leadingCoeff g) = g := by |
have g_ne_0 : g ≠ 0 := ne_zero_of_dvd_ne_zero (Monic.ne_zero <| hf.map (algebraMap R K)) hg
suffices lem : ∃ g' : R[X], g'.map (algebraMap R K) = g * C g.leadingCoeff⁻¹ by
obtain ⟨g', hg'⟩ := lem
use g'
rw [hg', mul_assoc, ← C_mul, inv_mul_cancel (leadingCoeff_ne_zero.mpr g_ne_0), C_1, mul_one]
have g_mul_dvd : g * C g.leadingCoeff⁻¹ ∣ f.map (algebraMap R K) := by
rwa [Associated.dvd_iff_dvd_left (show Associated (g * C g.leadingCoeff⁻¹) g from _)]
rw [associated_mul_isUnit_left_iff]
exact isUnit_C.mpr (inv_ne_zero <| leadingCoeff_ne_zero.mpr g_ne_0).isUnit
let algeq :=
(Subalgebra.equivOfEq _ _ <| integralClosure_eq_bot R _).trans
(Algebra.botEquivOfInjective <| IsFractionRing.injective R <| K)
have :
(algebraMap R _).comp algeq.toAlgHom.toRingHom = (integralClosure R _).toSubring.subtype := by
ext x; (conv_rhs => rw [← algeq.symm_apply_apply x]); rfl
have H :=
(mem_lifts _).1
(integralClosure.mem_lifts_of_monic_of_dvd_map K hf (monic_mul_leadingCoeff_inv g_ne_0)
g_mul_dvd)
refine ⟨map algeq.toAlgHom.toRingHom ?_, ?_⟩
· use! Classical.choose H
· rw [map_map, this]
exact Classical.choose_spec H
| 2,023 |
import Mathlib.FieldTheory.SplittingField.Construction
import Mathlib.RingTheory.Int.Basic
import Mathlib.RingTheory.Localization.Integral
import Mathlib.RingTheory.IntegrallyClosed
#align_import ring_theory.polynomial.gauss_lemma from "leanprover-community/mathlib"@"e3f4be1fcb5376c4948d7f095bec45350bfb9d1a"
open scoped nonZeroDivisors Polynomial
variable {R : Type*} [CommRing R]
namespace Polynomial
section
variable {S : Type*} [CommRing S] [IsDomain S]
variable {φ : R →+* S} (hinj : Function.Injective φ) {f : R[X]} (hf : f.IsPrimitive)
| Mathlib/RingTheory/Polynomial/GaussLemma.lean | 115 | 121 | theorem IsPrimitive.isUnit_iff_isUnit_map_of_injective : IsUnit f ↔ IsUnit (map φ f) := by |
refine ⟨(mapRingHom φ).isUnit_map, fun h => ?_⟩
rcases isUnit_iff.1 h with ⟨_, ⟨u, rfl⟩, hu⟩
have hdeg := degree_C u.ne_zero
rw [hu, degree_map_eq_of_injective hinj] at hdeg
rw [eq_C_of_degree_eq_zero hdeg] at hf ⊢
exact isUnit_C.mpr (isPrimitive_iff_isUnit_of_C_dvd.mp hf (f.coeff 0) dvd_rfl)
| 2,023 |
import Mathlib.FieldTheory.SplittingField.Construction
import Mathlib.RingTheory.Int.Basic
import Mathlib.RingTheory.Localization.Integral
import Mathlib.RingTheory.IntegrallyClosed
#align_import ring_theory.polynomial.gauss_lemma from "leanprover-community/mathlib"@"e3f4be1fcb5376c4948d7f095bec45350bfb9d1a"
open scoped nonZeroDivisors Polynomial
variable {R : Type*} [CommRing R]
namespace Polynomial
section
variable {S : Type*} [CommRing S] [IsDomain S]
variable {φ : R →+* S} (hinj : Function.Injective φ) {f : R[X]} (hf : f.IsPrimitive)
theorem IsPrimitive.isUnit_iff_isUnit_map_of_injective : IsUnit f ↔ IsUnit (map φ f) := by
refine ⟨(mapRingHom φ).isUnit_map, fun h => ?_⟩
rcases isUnit_iff.1 h with ⟨_, ⟨u, rfl⟩, hu⟩
have hdeg := degree_C u.ne_zero
rw [hu, degree_map_eq_of_injective hinj] at hdeg
rw [eq_C_of_degree_eq_zero hdeg] at hf ⊢
exact isUnit_C.mpr (isPrimitive_iff_isUnit_of_C_dvd.mp hf (f.coeff 0) dvd_rfl)
#align polynomial.is_primitive.is_unit_iff_is_unit_map_of_injective Polynomial.IsPrimitive.isUnit_iff_isUnit_map_of_injective
| Mathlib/RingTheory/Polynomial/GaussLemma.lean | 124 | 130 | theorem IsPrimitive.irreducible_of_irreducible_map_of_injective (h_irr : Irreducible (map φ f)) :
Irreducible f := by |
refine
⟨fun h => h_irr.not_unit (IsUnit.map (mapRingHom φ) h), fun a b h =>
(h_irr.isUnit_or_isUnit <| by rw [h, Polynomial.map_mul]).imp ?_ ?_⟩
all_goals apply ((isPrimitive_of_dvd hf _).isUnit_iff_isUnit_map_of_injective hinj).mpr
exacts [Dvd.intro _ h.symm, Dvd.intro_left _ h.symm]
| 2,023 |
import Mathlib.RingTheory.AdjoinRoot
import Mathlib.FieldTheory.Minpoly.Field
import Mathlib.RingTheory.Polynomial.GaussLemma
#align_import field_theory.minpoly.is_integrally_closed from "leanprover-community/mathlib"@"f0c8bf9245297a541f468be517f1bde6195105e9"
open scoped Classical Polynomial
open Polynomial Set Function minpoly
namespace minpoly
variable {R S : Type*} [CommRing R] [CommRing S] [IsDomain R] [Algebra R S]
section
variable (K L : Type*) [Field K] [Algebra R K] [IsFractionRing R K] [CommRing L] [Nontrivial L]
[Algebra R L] [Algebra S L] [Algebra K L] [IsScalarTower R K L] [IsScalarTower R S L]
variable [IsIntegrallyClosed R]
| Mathlib/FieldTheory/Minpoly/IsIntegrallyClosed.lean | 50 | 55 | theorem isIntegrallyClosed_eq_field_fractions [IsDomain S] {s : S} (hs : IsIntegral R s) :
minpoly K (algebraMap S L s) = (minpoly R s).map (algebraMap R K) := by |
refine (eq_of_irreducible_of_monic ?_ ?_ ?_).symm
· exact ((monic hs).irreducible_iff_irreducible_map_fraction_map).1 (irreducible hs)
· rw [aeval_map_algebraMap, aeval_algebraMap_apply, aeval, map_zero]
· exact (monic hs).map _
| 2,024 |
import Mathlib.RingTheory.AdjoinRoot
import Mathlib.FieldTheory.Minpoly.Field
import Mathlib.RingTheory.Polynomial.GaussLemma
#align_import field_theory.minpoly.is_integrally_closed from "leanprover-community/mathlib"@"f0c8bf9245297a541f468be517f1bde6195105e9"
open scoped Classical Polynomial
open Polynomial Set Function minpoly
namespace minpoly
variable {R S : Type*} [CommRing R] [CommRing S] [IsDomain R] [Algebra R S]
section
variable (K L : Type*) [Field K] [Algebra R K] [IsFractionRing R K] [CommRing L] [Nontrivial L]
[Algebra R L] [Algebra S L] [Algebra K L] [IsScalarTower R K L] [IsScalarTower R S L]
variable [IsIntegrallyClosed R]
theorem isIntegrallyClosed_eq_field_fractions [IsDomain S] {s : S} (hs : IsIntegral R s) :
minpoly K (algebraMap S L s) = (minpoly R s).map (algebraMap R K) := by
refine (eq_of_irreducible_of_monic ?_ ?_ ?_).symm
· exact ((monic hs).irreducible_iff_irreducible_map_fraction_map).1 (irreducible hs)
· rw [aeval_map_algebraMap, aeval_algebraMap_apply, aeval, map_zero]
· exact (monic hs).map _
#align minpoly.is_integrally_closed_eq_field_fractions minpoly.isIntegrallyClosed_eq_field_fractions
| Mathlib/FieldTheory/Minpoly/IsIntegrallyClosed.lean | 61 | 64 | theorem isIntegrallyClosed_eq_field_fractions' [IsDomain S] [Algebra K S] [IsScalarTower R K S]
{s : S} (hs : IsIntegral R s) : minpoly K s = (minpoly R s).map (algebraMap R K) := by |
let L := FractionRing S
rw [← isIntegrallyClosed_eq_field_fractions K L hs, algebraMap_eq (IsFractionRing.injective S L)]
| 2,024 |
import Mathlib.RingTheory.AdjoinRoot
import Mathlib.FieldTheory.Minpoly.Field
import Mathlib.RingTheory.Polynomial.GaussLemma
#align_import field_theory.minpoly.is_integrally_closed from "leanprover-community/mathlib"@"f0c8bf9245297a541f468be517f1bde6195105e9"
open scoped Classical Polynomial
open Polynomial Set Function minpoly
namespace minpoly
variable {R S : Type*} [CommRing R] [CommRing S] [IsDomain R] [Algebra R S]
section
variable (K L : Type*) [Field K] [Algebra R K] [IsFractionRing R K] [CommRing L] [Nontrivial L]
[Algebra R L] [Algebra S L] [Algebra K L] [IsScalarTower R K L] [IsScalarTower R S L]
variable [IsIntegrallyClosed R]
theorem isIntegrallyClosed_eq_field_fractions [IsDomain S] {s : S} (hs : IsIntegral R s) :
minpoly K (algebraMap S L s) = (minpoly R s).map (algebraMap R K) := by
refine (eq_of_irreducible_of_monic ?_ ?_ ?_).symm
· exact ((monic hs).irreducible_iff_irreducible_map_fraction_map).1 (irreducible hs)
· rw [aeval_map_algebraMap, aeval_algebraMap_apply, aeval, map_zero]
· exact (monic hs).map _
#align minpoly.is_integrally_closed_eq_field_fractions minpoly.isIntegrallyClosed_eq_field_fractions
theorem isIntegrallyClosed_eq_field_fractions' [IsDomain S] [Algebra K S] [IsScalarTower R K S]
{s : S} (hs : IsIntegral R s) : minpoly K s = (minpoly R s).map (algebraMap R K) := by
let L := FractionRing S
rw [← isIntegrallyClosed_eq_field_fractions K L hs, algebraMap_eq (IsFractionRing.injective S L)]
#align minpoly.is_integrally_closed_eq_field_fractions' minpoly.isIntegrallyClosed_eq_field_fractions'
end
variable [IsDomain S] [NoZeroSMulDivisors R S]
variable [IsIntegrallyClosed R]
| Mathlib/FieldTheory/Minpoly/IsIntegrallyClosed.lean | 75 | 92 | theorem isIntegrallyClosed_dvd {s : S} (hs : IsIntegral R s) {p : R[X]}
(hp : Polynomial.aeval s p = 0) : minpoly R s ∣ p := by |
let K := FractionRing R
let L := FractionRing S
let _ : Algebra K L := FractionRing.liftAlgebra R L
have := FractionRing.isScalarTower_liftAlgebra R L
have : minpoly K (algebraMap S L s) ∣ map (algebraMap R K) (p %ₘ minpoly R s) := by
rw [map_modByMonic _ (minpoly.monic hs), modByMonic_eq_sub_mul_div]
· refine dvd_sub (minpoly.dvd K (algebraMap S L s) ?_) ?_
· rw [← map_aeval_eq_aeval_map, hp, map_zero]
rw [← IsScalarTower.algebraMap_eq, ← IsScalarTower.algebraMap_eq]
apply dvd_mul_of_dvd_left
rw [isIntegrallyClosed_eq_field_fractions K L hs]
exact Monic.map _ (minpoly.monic hs)
rw [isIntegrallyClosed_eq_field_fractions _ _ hs,
map_dvd_map (algebraMap R K) (IsFractionRing.injective R K) (minpoly.monic hs)] at this
rw [← modByMonic_eq_zero_iff_dvd (minpoly.monic hs)]
exact Polynomial.eq_zero_of_dvd_of_degree_lt this (degree_modByMonic_lt p <| minpoly.monic hs)
| 2,024 |
import Mathlib.RingTheory.AdjoinRoot
import Mathlib.FieldTheory.Minpoly.Field
import Mathlib.RingTheory.Polynomial.GaussLemma
#align_import field_theory.minpoly.is_integrally_closed from "leanprover-community/mathlib"@"f0c8bf9245297a541f468be517f1bde6195105e9"
open scoped Classical Polynomial
open Polynomial Set Function minpoly
namespace minpoly
variable {R S : Type*} [CommRing R] [CommRing S] [IsDomain R] [Algebra R S]
section
variable (K L : Type*) [Field K] [Algebra R K] [IsFractionRing R K] [CommRing L] [Nontrivial L]
[Algebra R L] [Algebra S L] [Algebra K L] [IsScalarTower R K L] [IsScalarTower R S L]
variable [IsIntegrallyClosed R]
theorem isIntegrallyClosed_eq_field_fractions [IsDomain S] {s : S} (hs : IsIntegral R s) :
minpoly K (algebraMap S L s) = (minpoly R s).map (algebraMap R K) := by
refine (eq_of_irreducible_of_monic ?_ ?_ ?_).symm
· exact ((monic hs).irreducible_iff_irreducible_map_fraction_map).1 (irreducible hs)
· rw [aeval_map_algebraMap, aeval_algebraMap_apply, aeval, map_zero]
· exact (monic hs).map _
#align minpoly.is_integrally_closed_eq_field_fractions minpoly.isIntegrallyClosed_eq_field_fractions
theorem isIntegrallyClosed_eq_field_fractions' [IsDomain S] [Algebra K S] [IsScalarTower R K S]
{s : S} (hs : IsIntegral R s) : minpoly K s = (minpoly R s).map (algebraMap R K) := by
let L := FractionRing S
rw [← isIntegrallyClosed_eq_field_fractions K L hs, algebraMap_eq (IsFractionRing.injective S L)]
#align minpoly.is_integrally_closed_eq_field_fractions' minpoly.isIntegrallyClosed_eq_field_fractions'
end
variable [IsDomain S] [NoZeroSMulDivisors R S]
variable [IsIntegrallyClosed R]
theorem isIntegrallyClosed_dvd {s : S} (hs : IsIntegral R s) {p : R[X]}
(hp : Polynomial.aeval s p = 0) : minpoly R s ∣ p := by
let K := FractionRing R
let L := FractionRing S
let _ : Algebra K L := FractionRing.liftAlgebra R L
have := FractionRing.isScalarTower_liftAlgebra R L
have : minpoly K (algebraMap S L s) ∣ map (algebraMap R K) (p %ₘ minpoly R s) := by
rw [map_modByMonic _ (minpoly.monic hs), modByMonic_eq_sub_mul_div]
· refine dvd_sub (minpoly.dvd K (algebraMap S L s) ?_) ?_
· rw [← map_aeval_eq_aeval_map, hp, map_zero]
rw [← IsScalarTower.algebraMap_eq, ← IsScalarTower.algebraMap_eq]
apply dvd_mul_of_dvd_left
rw [isIntegrallyClosed_eq_field_fractions K L hs]
exact Monic.map _ (minpoly.monic hs)
rw [isIntegrallyClosed_eq_field_fractions _ _ hs,
map_dvd_map (algebraMap R K) (IsFractionRing.injective R K) (minpoly.monic hs)] at this
rw [← modByMonic_eq_zero_iff_dvd (minpoly.monic hs)]
exact Polynomial.eq_zero_of_dvd_of_degree_lt this (degree_modByMonic_lt p <| minpoly.monic hs)
#align minpoly.is_integrally_closed_dvd minpoly.isIntegrallyClosed_dvd
theorem isIntegrallyClosed_dvd_iff {s : S} (hs : IsIntegral R s) (p : R[X]) :
Polynomial.aeval s p = 0 ↔ minpoly R s ∣ p :=
⟨fun hp => isIntegrallyClosed_dvd hs hp, fun hp => by
simpa only [RingHom.mem_ker, RingHom.coe_comp, coe_evalRingHom, coe_mapRingHom,
Function.comp_apply, eval_map, ← aeval_def] using
aeval_eq_zero_of_dvd_aeval_eq_zero hp (minpoly.aeval R s)⟩
#align minpoly.is_integrally_closed_dvd_iff minpoly.isIntegrallyClosed_dvd_iff
| Mathlib/FieldTheory/Minpoly/IsIntegrallyClosed.lean | 103 | 108 | theorem ker_eval {s : S} (hs : IsIntegral R s) :
RingHom.ker ((Polynomial.aeval s).toRingHom : R[X] →+* S) =
Ideal.span ({minpoly R s} : Set R[X]) := by |
ext p
simp_rw [RingHom.mem_ker, AlgHom.toRingHom_eq_coe, AlgHom.coe_toRingHom,
isIntegrallyClosed_dvd_iff hs, ← Ideal.mem_span_singleton]
| 2,024 |
import Mathlib.RingTheory.AdjoinRoot
import Mathlib.FieldTheory.Minpoly.Field
import Mathlib.RingTheory.Polynomial.GaussLemma
#align_import field_theory.minpoly.is_integrally_closed from "leanprover-community/mathlib"@"f0c8bf9245297a541f468be517f1bde6195105e9"
open scoped Classical Polynomial
open Polynomial Set Function minpoly
namespace minpoly
variable {R S : Type*} [CommRing R] [CommRing S] [IsDomain R] [Algebra R S]
section
variable (K L : Type*) [Field K] [Algebra R K] [IsFractionRing R K] [CommRing L] [Nontrivial L]
[Algebra R L] [Algebra S L] [Algebra K L] [IsScalarTower R K L] [IsScalarTower R S L]
variable [IsIntegrallyClosed R]
theorem isIntegrallyClosed_eq_field_fractions [IsDomain S] {s : S} (hs : IsIntegral R s) :
minpoly K (algebraMap S L s) = (minpoly R s).map (algebraMap R K) := by
refine (eq_of_irreducible_of_monic ?_ ?_ ?_).symm
· exact ((monic hs).irreducible_iff_irreducible_map_fraction_map).1 (irreducible hs)
· rw [aeval_map_algebraMap, aeval_algebraMap_apply, aeval, map_zero]
· exact (monic hs).map _
#align minpoly.is_integrally_closed_eq_field_fractions minpoly.isIntegrallyClosed_eq_field_fractions
theorem isIntegrallyClosed_eq_field_fractions' [IsDomain S] [Algebra K S] [IsScalarTower R K S]
{s : S} (hs : IsIntegral R s) : minpoly K s = (minpoly R s).map (algebraMap R K) := by
let L := FractionRing S
rw [← isIntegrallyClosed_eq_field_fractions K L hs, algebraMap_eq (IsFractionRing.injective S L)]
#align minpoly.is_integrally_closed_eq_field_fractions' minpoly.isIntegrallyClosed_eq_field_fractions'
end
variable [IsDomain S] [NoZeroSMulDivisors R S]
variable [IsIntegrallyClosed R]
theorem isIntegrallyClosed_dvd {s : S} (hs : IsIntegral R s) {p : R[X]}
(hp : Polynomial.aeval s p = 0) : minpoly R s ∣ p := by
let K := FractionRing R
let L := FractionRing S
let _ : Algebra K L := FractionRing.liftAlgebra R L
have := FractionRing.isScalarTower_liftAlgebra R L
have : minpoly K (algebraMap S L s) ∣ map (algebraMap R K) (p %ₘ minpoly R s) := by
rw [map_modByMonic _ (minpoly.monic hs), modByMonic_eq_sub_mul_div]
· refine dvd_sub (minpoly.dvd K (algebraMap S L s) ?_) ?_
· rw [← map_aeval_eq_aeval_map, hp, map_zero]
rw [← IsScalarTower.algebraMap_eq, ← IsScalarTower.algebraMap_eq]
apply dvd_mul_of_dvd_left
rw [isIntegrallyClosed_eq_field_fractions K L hs]
exact Monic.map _ (minpoly.monic hs)
rw [isIntegrallyClosed_eq_field_fractions _ _ hs,
map_dvd_map (algebraMap R K) (IsFractionRing.injective R K) (minpoly.monic hs)] at this
rw [← modByMonic_eq_zero_iff_dvd (minpoly.monic hs)]
exact Polynomial.eq_zero_of_dvd_of_degree_lt this (degree_modByMonic_lt p <| minpoly.monic hs)
#align minpoly.is_integrally_closed_dvd minpoly.isIntegrallyClosed_dvd
theorem isIntegrallyClosed_dvd_iff {s : S} (hs : IsIntegral R s) (p : R[X]) :
Polynomial.aeval s p = 0 ↔ minpoly R s ∣ p :=
⟨fun hp => isIntegrallyClosed_dvd hs hp, fun hp => by
simpa only [RingHom.mem_ker, RingHom.coe_comp, coe_evalRingHom, coe_mapRingHom,
Function.comp_apply, eval_map, ← aeval_def] using
aeval_eq_zero_of_dvd_aeval_eq_zero hp (minpoly.aeval R s)⟩
#align minpoly.is_integrally_closed_dvd_iff minpoly.isIntegrallyClosed_dvd_iff
theorem ker_eval {s : S} (hs : IsIntegral R s) :
RingHom.ker ((Polynomial.aeval s).toRingHom : R[X] →+* S) =
Ideal.span ({minpoly R s} : Set R[X]) := by
ext p
simp_rw [RingHom.mem_ker, AlgHom.toRingHom_eq_coe, AlgHom.coe_toRingHom,
isIntegrallyClosed_dvd_iff hs, ← Ideal.mem_span_singleton]
#align minpoly.ker_eval minpoly.ker_eval
| Mathlib/FieldTheory/Minpoly/IsIntegrallyClosed.lean | 114 | 118 | theorem IsIntegrallyClosed.degree_le_of_ne_zero {s : S} (hs : IsIntegral R s) {p : R[X]}
(hp0 : p ≠ 0) (hp : Polynomial.aeval s p = 0) : degree (minpoly R s) ≤ degree p := by |
rw [degree_eq_natDegree (minpoly.ne_zero hs), degree_eq_natDegree hp0]
norm_cast
exact natDegree_le_of_dvd ((isIntegrallyClosed_dvd_iff hs _).mp hp) hp0
| 2,024 |
import Mathlib.RingTheory.AdjoinRoot
import Mathlib.FieldTheory.Minpoly.Field
import Mathlib.RingTheory.Polynomial.GaussLemma
#align_import field_theory.minpoly.is_integrally_closed from "leanprover-community/mathlib"@"f0c8bf9245297a541f468be517f1bde6195105e9"
open scoped Classical Polynomial
open Polynomial Set Function minpoly
namespace minpoly
variable {R S : Type*} [CommRing R] [CommRing S] [IsDomain R] [Algebra R S]
section
variable (K L : Type*) [Field K] [Algebra R K] [IsFractionRing R K] [CommRing L] [Nontrivial L]
[Algebra R L] [Algebra S L] [Algebra K L] [IsScalarTower R K L] [IsScalarTower R S L]
variable [IsIntegrallyClosed R]
theorem isIntegrallyClosed_eq_field_fractions [IsDomain S] {s : S} (hs : IsIntegral R s) :
minpoly K (algebraMap S L s) = (minpoly R s).map (algebraMap R K) := by
refine (eq_of_irreducible_of_monic ?_ ?_ ?_).symm
· exact ((monic hs).irreducible_iff_irreducible_map_fraction_map).1 (irreducible hs)
· rw [aeval_map_algebraMap, aeval_algebraMap_apply, aeval, map_zero]
· exact (monic hs).map _
#align minpoly.is_integrally_closed_eq_field_fractions minpoly.isIntegrallyClosed_eq_field_fractions
theorem isIntegrallyClosed_eq_field_fractions' [IsDomain S] [Algebra K S] [IsScalarTower R K S]
{s : S} (hs : IsIntegral R s) : minpoly K s = (minpoly R s).map (algebraMap R K) := by
let L := FractionRing S
rw [← isIntegrallyClosed_eq_field_fractions K L hs, algebraMap_eq (IsFractionRing.injective S L)]
#align minpoly.is_integrally_closed_eq_field_fractions' minpoly.isIntegrallyClosed_eq_field_fractions'
end
variable [IsDomain S] [NoZeroSMulDivisors R S]
variable [IsIntegrallyClosed R]
theorem isIntegrallyClosed_dvd {s : S} (hs : IsIntegral R s) {p : R[X]}
(hp : Polynomial.aeval s p = 0) : minpoly R s ∣ p := by
let K := FractionRing R
let L := FractionRing S
let _ : Algebra K L := FractionRing.liftAlgebra R L
have := FractionRing.isScalarTower_liftAlgebra R L
have : minpoly K (algebraMap S L s) ∣ map (algebraMap R K) (p %ₘ minpoly R s) := by
rw [map_modByMonic _ (minpoly.monic hs), modByMonic_eq_sub_mul_div]
· refine dvd_sub (minpoly.dvd K (algebraMap S L s) ?_) ?_
· rw [← map_aeval_eq_aeval_map, hp, map_zero]
rw [← IsScalarTower.algebraMap_eq, ← IsScalarTower.algebraMap_eq]
apply dvd_mul_of_dvd_left
rw [isIntegrallyClosed_eq_field_fractions K L hs]
exact Monic.map _ (minpoly.monic hs)
rw [isIntegrallyClosed_eq_field_fractions _ _ hs,
map_dvd_map (algebraMap R K) (IsFractionRing.injective R K) (minpoly.monic hs)] at this
rw [← modByMonic_eq_zero_iff_dvd (minpoly.monic hs)]
exact Polynomial.eq_zero_of_dvd_of_degree_lt this (degree_modByMonic_lt p <| minpoly.monic hs)
#align minpoly.is_integrally_closed_dvd minpoly.isIntegrallyClosed_dvd
theorem isIntegrallyClosed_dvd_iff {s : S} (hs : IsIntegral R s) (p : R[X]) :
Polynomial.aeval s p = 0 ↔ minpoly R s ∣ p :=
⟨fun hp => isIntegrallyClosed_dvd hs hp, fun hp => by
simpa only [RingHom.mem_ker, RingHom.coe_comp, coe_evalRingHom, coe_mapRingHom,
Function.comp_apply, eval_map, ← aeval_def] using
aeval_eq_zero_of_dvd_aeval_eq_zero hp (minpoly.aeval R s)⟩
#align minpoly.is_integrally_closed_dvd_iff minpoly.isIntegrallyClosed_dvd_iff
theorem ker_eval {s : S} (hs : IsIntegral R s) :
RingHom.ker ((Polynomial.aeval s).toRingHom : R[X] →+* S) =
Ideal.span ({minpoly R s} : Set R[X]) := by
ext p
simp_rw [RingHom.mem_ker, AlgHom.toRingHom_eq_coe, AlgHom.coe_toRingHom,
isIntegrallyClosed_dvd_iff hs, ← Ideal.mem_span_singleton]
#align minpoly.ker_eval minpoly.ker_eval
theorem IsIntegrallyClosed.degree_le_of_ne_zero {s : S} (hs : IsIntegral R s) {p : R[X]}
(hp0 : p ≠ 0) (hp : Polynomial.aeval s p = 0) : degree (minpoly R s) ≤ degree p := by
rw [degree_eq_natDegree (minpoly.ne_zero hs), degree_eq_natDegree hp0]
norm_cast
exact natDegree_le_of_dvd ((isIntegrallyClosed_dvd_iff hs _).mp hp) hp0
#align minpoly.is_integrally_closed.degree_le_of_ne_zero minpoly.IsIntegrallyClosed.degree_le_of_ne_zero
| Mathlib/FieldTheory/Minpoly/IsIntegrallyClosed.lean | 125 | 135 | theorem _root_.IsIntegrallyClosed.minpoly.unique {s : S} {P : R[X]} (hmo : P.Monic)
(hP : Polynomial.aeval s P = 0)
(Pmin : ∀ Q : R[X], Q.Monic → Polynomial.aeval s Q = 0 → degree P ≤ degree Q) :
P = minpoly R s := by |
have hs : IsIntegral R s := ⟨P, hmo, hP⟩
symm; apply eq_of_sub_eq_zero
by_contra hnz
refine IsIntegrallyClosed.degree_le_of_ne_zero hs hnz (by simp [hP]) |>.not_lt ?_
refine degree_sub_lt ?_ (ne_zero hs) ?_
· exact le_antisymm (min R s hmo hP) (Pmin (minpoly R s) (monic hs) (aeval R s))
· rw [(monic hs).leadingCoeff, hmo.leadingCoeff]
| 2,024 |
import Mathlib.RingTheory.AdjoinRoot
import Mathlib.FieldTheory.Minpoly.Field
import Mathlib.RingTheory.Polynomial.GaussLemma
#align_import field_theory.minpoly.is_integrally_closed from "leanprover-community/mathlib"@"f0c8bf9245297a541f468be517f1bde6195105e9"
open scoped Classical Polynomial
open Polynomial Set Function minpoly
namespace minpoly
variable {R S : Type*} [CommRing R] [CommRing S] [IsDomain R] [Algebra R S]
section
variable (K L : Type*) [Field K] [Algebra R K] [IsFractionRing R K] [CommRing L] [Nontrivial L]
[Algebra R L] [Algebra S L] [Algebra K L] [IsScalarTower R K L] [IsScalarTower R S L]
variable [IsIntegrallyClosed R]
theorem isIntegrallyClosed_eq_field_fractions [IsDomain S] {s : S} (hs : IsIntegral R s) :
minpoly K (algebraMap S L s) = (minpoly R s).map (algebraMap R K) := by
refine (eq_of_irreducible_of_monic ?_ ?_ ?_).symm
· exact ((monic hs).irreducible_iff_irreducible_map_fraction_map).1 (irreducible hs)
· rw [aeval_map_algebraMap, aeval_algebraMap_apply, aeval, map_zero]
· exact (monic hs).map _
#align minpoly.is_integrally_closed_eq_field_fractions minpoly.isIntegrallyClosed_eq_field_fractions
theorem isIntegrallyClosed_eq_field_fractions' [IsDomain S] [Algebra K S] [IsScalarTower R K S]
{s : S} (hs : IsIntegral R s) : minpoly K s = (minpoly R s).map (algebraMap R K) := by
let L := FractionRing S
rw [← isIntegrallyClosed_eq_field_fractions K L hs, algebraMap_eq (IsFractionRing.injective S L)]
#align minpoly.is_integrally_closed_eq_field_fractions' minpoly.isIntegrallyClosed_eq_field_fractions'
end
variable [IsDomain S] [NoZeroSMulDivisors R S]
variable [IsIntegrallyClosed R]
theorem isIntegrallyClosed_dvd {s : S} (hs : IsIntegral R s) {p : R[X]}
(hp : Polynomial.aeval s p = 0) : minpoly R s ∣ p := by
let K := FractionRing R
let L := FractionRing S
let _ : Algebra K L := FractionRing.liftAlgebra R L
have := FractionRing.isScalarTower_liftAlgebra R L
have : minpoly K (algebraMap S L s) ∣ map (algebraMap R K) (p %ₘ minpoly R s) := by
rw [map_modByMonic _ (minpoly.monic hs), modByMonic_eq_sub_mul_div]
· refine dvd_sub (minpoly.dvd K (algebraMap S L s) ?_) ?_
· rw [← map_aeval_eq_aeval_map, hp, map_zero]
rw [← IsScalarTower.algebraMap_eq, ← IsScalarTower.algebraMap_eq]
apply dvd_mul_of_dvd_left
rw [isIntegrallyClosed_eq_field_fractions K L hs]
exact Monic.map _ (minpoly.monic hs)
rw [isIntegrallyClosed_eq_field_fractions _ _ hs,
map_dvd_map (algebraMap R K) (IsFractionRing.injective R K) (minpoly.monic hs)] at this
rw [← modByMonic_eq_zero_iff_dvd (minpoly.monic hs)]
exact Polynomial.eq_zero_of_dvd_of_degree_lt this (degree_modByMonic_lt p <| minpoly.monic hs)
#align minpoly.is_integrally_closed_dvd minpoly.isIntegrallyClosed_dvd
theorem isIntegrallyClosed_dvd_iff {s : S} (hs : IsIntegral R s) (p : R[X]) :
Polynomial.aeval s p = 0 ↔ minpoly R s ∣ p :=
⟨fun hp => isIntegrallyClosed_dvd hs hp, fun hp => by
simpa only [RingHom.mem_ker, RingHom.coe_comp, coe_evalRingHom, coe_mapRingHom,
Function.comp_apply, eval_map, ← aeval_def] using
aeval_eq_zero_of_dvd_aeval_eq_zero hp (minpoly.aeval R s)⟩
#align minpoly.is_integrally_closed_dvd_iff minpoly.isIntegrallyClosed_dvd_iff
theorem ker_eval {s : S} (hs : IsIntegral R s) :
RingHom.ker ((Polynomial.aeval s).toRingHom : R[X] →+* S) =
Ideal.span ({minpoly R s} : Set R[X]) := by
ext p
simp_rw [RingHom.mem_ker, AlgHom.toRingHom_eq_coe, AlgHom.coe_toRingHom,
isIntegrallyClosed_dvd_iff hs, ← Ideal.mem_span_singleton]
#align minpoly.ker_eval minpoly.ker_eval
theorem IsIntegrallyClosed.degree_le_of_ne_zero {s : S} (hs : IsIntegral R s) {p : R[X]}
(hp0 : p ≠ 0) (hp : Polynomial.aeval s p = 0) : degree (minpoly R s) ≤ degree p := by
rw [degree_eq_natDegree (minpoly.ne_zero hs), degree_eq_natDegree hp0]
norm_cast
exact natDegree_le_of_dvd ((isIntegrallyClosed_dvd_iff hs _).mp hp) hp0
#align minpoly.is_integrally_closed.degree_le_of_ne_zero minpoly.IsIntegrallyClosed.degree_le_of_ne_zero
theorem _root_.IsIntegrallyClosed.minpoly.unique {s : S} {P : R[X]} (hmo : P.Monic)
(hP : Polynomial.aeval s P = 0)
(Pmin : ∀ Q : R[X], Q.Monic → Polynomial.aeval s Q = 0 → degree P ≤ degree Q) :
P = minpoly R s := by
have hs : IsIntegral R s := ⟨P, hmo, hP⟩
symm; apply eq_of_sub_eq_zero
by_contra hnz
refine IsIntegrallyClosed.degree_le_of_ne_zero hs hnz (by simp [hP]) |>.not_lt ?_
refine degree_sub_lt ?_ (ne_zero hs) ?_
· exact le_antisymm (min R s hmo hP) (Pmin (minpoly R s) (monic hs) (aeval R s))
· rw [(monic hs).leadingCoeff, hmo.leadingCoeff]
#align minpoly.is_integrally_closed.minpoly.unique IsIntegrallyClosed.minpoly.unique
| Mathlib/FieldTheory/Minpoly/IsIntegrallyClosed.lean | 138 | 145 | theorem prime_of_isIntegrallyClosed {x : S} (hx : IsIntegral R x) : Prime (minpoly R x) := by |
refine
⟨(minpoly.monic hx).ne_zero,
⟨fun h_contra => (ne_of_lt (minpoly.degree_pos hx)) (degree_eq_zero_of_isUnit h_contra).symm,
fun a b h => or_iff_not_imp_left.mpr fun h' => ?_⟩⟩
rw [← minpoly.isIntegrallyClosed_dvd_iff hx] at h' h ⊢
rw [aeval_mul] at h
exact eq_zero_of_ne_zero_of_mul_left_eq_zero h' h
| 2,024 |
import Mathlib.RingTheory.RootsOfUnity.Basic
import Mathlib.FieldTheory.Minpoly.IsIntegrallyClosed
import Mathlib.Algebra.GCDMonoid.IntegrallyClosed
import Mathlib.FieldTheory.Finite.Basic
#align_import ring_theory.roots_of_unity.minpoly from "leanprover-community/mathlib"@"7fdeecc0d03cd40f7a165e6cf00a4d2286db599f"
open minpoly Polynomial
open scoped Polynomial
namespace IsPrimitiveRoot
section CommRing
variable {n : ℕ} {K : Type*} [CommRing K] {μ : K} (h : IsPrimitiveRoot μ n)
-- Porting note: `hpos` was in the `variable` line, with an `omit` in mathlib3 just after this
-- declaration. For some reason, in Lean4, `hpos` gets included also in the declarations below,
-- even if it is not used in the proof.
| Mathlib/RingTheory/RootsOfUnity/Minpoly.lean | 40 | 45 | theorem isIntegral (hpos : 0 < n) : IsIntegral ℤ μ := by |
use X ^ n - 1
constructor
· exact monic_X_pow_sub_C 1 (ne_of_lt hpos).symm
· simp only [((IsPrimitiveRoot.iff_def μ n).mp h).left, eval₂_one, eval₂_X_pow, eval₂_sub,
sub_self]
| 2,025 |
import Mathlib.RingTheory.RootsOfUnity.Basic
import Mathlib.FieldTheory.Minpoly.IsIntegrallyClosed
import Mathlib.Algebra.GCDMonoid.IntegrallyClosed
import Mathlib.FieldTheory.Finite.Basic
#align_import ring_theory.roots_of_unity.minpoly from "leanprover-community/mathlib"@"7fdeecc0d03cd40f7a165e6cf00a4d2286db599f"
open minpoly Polynomial
open scoped Polynomial
namespace IsPrimitiveRoot
section CommRing
variable {n : ℕ} {K : Type*} [CommRing K] {μ : K} (h : IsPrimitiveRoot μ n)
-- Porting note: `hpos` was in the `variable` line, with an `omit` in mathlib3 just after this
-- declaration. For some reason, in Lean4, `hpos` gets included also in the declarations below,
-- even if it is not used in the proof.
theorem isIntegral (hpos : 0 < n) : IsIntegral ℤ μ := by
use X ^ n - 1
constructor
· exact monic_X_pow_sub_C 1 (ne_of_lt hpos).symm
· simp only [((IsPrimitiveRoot.iff_def μ n).mp h).left, eval₂_one, eval₂_X_pow, eval₂_sub,
sub_self]
#align is_primitive_root.is_integral IsPrimitiveRoot.isIntegral
section IsDomain
variable [IsDomain K] [CharZero K]
| Mathlib/RingTheory/RootsOfUnity/Minpoly.lean | 53 | 58 | theorem minpoly_dvd_x_pow_sub_one : minpoly ℤ μ ∣ X ^ n - 1 := by |
rcases n.eq_zero_or_pos with (rfl | h0)
· simp
apply minpoly.isIntegrallyClosed_dvd (isIntegral h h0)
simp only [((IsPrimitiveRoot.iff_def μ n).mp h).left, aeval_X_pow, eq_intCast, Int.cast_one,
aeval_one, AlgHom.map_sub, sub_self]
| 2,025 |
import Mathlib.RingTheory.RootsOfUnity.Basic
import Mathlib.FieldTheory.Minpoly.IsIntegrallyClosed
import Mathlib.Algebra.GCDMonoid.IntegrallyClosed
import Mathlib.FieldTheory.Finite.Basic
#align_import ring_theory.roots_of_unity.minpoly from "leanprover-community/mathlib"@"7fdeecc0d03cd40f7a165e6cf00a4d2286db599f"
open minpoly Polynomial
open scoped Polynomial
namespace IsPrimitiveRoot
section CommRing
variable {n : ℕ} {K : Type*} [CommRing K] {μ : K} (h : IsPrimitiveRoot μ n)
-- Porting note: `hpos` was in the `variable` line, with an `omit` in mathlib3 just after this
-- declaration. For some reason, in Lean4, `hpos` gets included also in the declarations below,
-- even if it is not used in the proof.
theorem isIntegral (hpos : 0 < n) : IsIntegral ℤ μ := by
use X ^ n - 1
constructor
· exact monic_X_pow_sub_C 1 (ne_of_lt hpos).symm
· simp only [((IsPrimitiveRoot.iff_def μ n).mp h).left, eval₂_one, eval₂_X_pow, eval₂_sub,
sub_self]
#align is_primitive_root.is_integral IsPrimitiveRoot.isIntegral
section IsDomain
variable [IsDomain K] [CharZero K]
theorem minpoly_dvd_x_pow_sub_one : minpoly ℤ μ ∣ X ^ n - 1 := by
rcases n.eq_zero_or_pos with (rfl | h0)
· simp
apply minpoly.isIntegrallyClosed_dvd (isIntegral h h0)
simp only [((IsPrimitiveRoot.iff_def μ n).mp h).left, aeval_X_pow, eq_intCast, Int.cast_one,
aeval_one, AlgHom.map_sub, sub_self]
set_option linter.uppercaseLean3 false in
#align is_primitive_root.minpoly_dvd_X_pow_sub_one IsPrimitiveRoot.minpoly_dvd_x_pow_sub_one
| Mathlib/RingTheory/RootsOfUnity/Minpoly.lean | 63 | 71 | theorem separable_minpoly_mod {p : ℕ} [Fact p.Prime] (hdiv : ¬p ∣ n) :
Separable (map (Int.castRingHom (ZMod p)) (minpoly ℤ μ)) := by |
have hdvd : map (Int.castRingHom (ZMod p)) (minpoly ℤ μ) ∣ X ^ n - 1 := by
convert RingHom.map_dvd (mapRingHom (Int.castRingHom (ZMod p)))
(minpoly_dvd_x_pow_sub_one h)
simp only [map_sub, map_pow, coe_mapRingHom, map_X, map_one]
refine Separable.of_dvd (separable_X_pow_sub_C 1 ?_ one_ne_zero) hdvd
by_contra hzero
exact hdiv ((ZMod.natCast_zmod_eq_zero_iff_dvd n p).1 hzero)
| 2,025 |
import Mathlib.RingTheory.RootsOfUnity.Basic
import Mathlib.FieldTheory.Minpoly.IsIntegrallyClosed
import Mathlib.Algebra.GCDMonoid.IntegrallyClosed
import Mathlib.FieldTheory.Finite.Basic
#align_import ring_theory.roots_of_unity.minpoly from "leanprover-community/mathlib"@"7fdeecc0d03cd40f7a165e6cf00a4d2286db599f"
open minpoly Polynomial
open scoped Polynomial
namespace IsPrimitiveRoot
section CommRing
variable {n : ℕ} {K : Type*} [CommRing K] {μ : K} (h : IsPrimitiveRoot μ n)
-- Porting note: `hpos` was in the `variable` line, with an `omit` in mathlib3 just after this
-- declaration. For some reason, in Lean4, `hpos` gets included also in the declarations below,
-- even if it is not used in the proof.
theorem isIntegral (hpos : 0 < n) : IsIntegral ℤ μ := by
use X ^ n - 1
constructor
· exact monic_X_pow_sub_C 1 (ne_of_lt hpos).symm
· simp only [((IsPrimitiveRoot.iff_def μ n).mp h).left, eval₂_one, eval₂_X_pow, eval₂_sub,
sub_self]
#align is_primitive_root.is_integral IsPrimitiveRoot.isIntegral
section IsDomain
variable [IsDomain K] [CharZero K]
theorem minpoly_dvd_x_pow_sub_one : minpoly ℤ μ ∣ X ^ n - 1 := by
rcases n.eq_zero_or_pos with (rfl | h0)
· simp
apply minpoly.isIntegrallyClosed_dvd (isIntegral h h0)
simp only [((IsPrimitiveRoot.iff_def μ n).mp h).left, aeval_X_pow, eq_intCast, Int.cast_one,
aeval_one, AlgHom.map_sub, sub_self]
set_option linter.uppercaseLean3 false in
#align is_primitive_root.minpoly_dvd_X_pow_sub_one IsPrimitiveRoot.minpoly_dvd_x_pow_sub_one
theorem separable_minpoly_mod {p : ℕ} [Fact p.Prime] (hdiv : ¬p ∣ n) :
Separable (map (Int.castRingHom (ZMod p)) (minpoly ℤ μ)) := by
have hdvd : map (Int.castRingHom (ZMod p)) (minpoly ℤ μ) ∣ X ^ n - 1 := by
convert RingHom.map_dvd (mapRingHom (Int.castRingHom (ZMod p)))
(minpoly_dvd_x_pow_sub_one h)
simp only [map_sub, map_pow, coe_mapRingHom, map_X, map_one]
refine Separable.of_dvd (separable_X_pow_sub_C 1 ?_ one_ne_zero) hdvd
by_contra hzero
exact hdiv ((ZMod.natCast_zmod_eq_zero_iff_dvd n p).1 hzero)
#align is_primitive_root.separable_minpoly_mod IsPrimitiveRoot.separable_minpoly_mod
theorem squarefree_minpoly_mod {p : ℕ} [Fact p.Prime] (hdiv : ¬p ∣ n) :
Squarefree (map (Int.castRingHom (ZMod p)) (minpoly ℤ μ)) :=
(separable_minpoly_mod h hdiv).squarefree
#align is_primitive_root.squarefree_minpoly_mod IsPrimitiveRoot.squarefree_minpoly_mod
| Mathlib/RingTheory/RootsOfUnity/Minpoly.lean | 82 | 90 | theorem minpoly_dvd_expand {p : ℕ} (hdiv : ¬p ∣ n) :
minpoly ℤ μ ∣ expand ℤ p (minpoly ℤ (μ ^ p)) := by |
rcases n.eq_zero_or_pos with (rfl | hpos)
· simp_all
letI : IsIntegrallyClosed ℤ := GCDMonoid.toIsIntegrallyClosed
refine minpoly.isIntegrallyClosed_dvd (h.isIntegral hpos) ?_
rw [aeval_def, coe_expand, ← comp, eval₂_eq_eval_map, map_comp, Polynomial.map_pow, map_X,
eval_comp, eval_pow, eval_X, ← eval₂_eq_eval_map, ← aeval_def]
exact minpoly.aeval _ _
| 2,025 |
Subsets and Splits
No community queries yet
The top public SQL queries from the community will appear here once available.