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div_eq_of_eq_mul (h : is_unit b) : a = c * b → a / b = c
h.div_eq_iff.2
lemma
is_unit.div_eq_of_eq_mul
algebra.hom
src/algebra/hom/units.lean
[ "algebra.hom.group", "algebra.group.units" ]
[ "div_eq_of_eq_mul", "is_unit" ]
https://github.com/leanprover-community/mathlib
65a1391a0106c9204fe45bc73a039f056558cb83
eq_div_of_mul_eq (h : is_unit c) : a * c = b → a = b / c
h.eq_div_iff.2
lemma
is_unit.eq_div_of_mul_eq
algebra.hom
src/algebra/hom/units.lean
[ "algebra.hom.group", "algebra.group.units" ]
[ "eq_div_of_mul_eq", "is_unit" ]
https://github.com/leanprover-community/mathlib
65a1391a0106c9204fe45bc73a039f056558cb83
div_eq_one_iff_eq (h : is_unit b) : a / b = 1 ↔ a = b
⟨eq_of_div_eq_one, λ hab, hab.symm ▸ h.div_self⟩
lemma
is_unit.div_eq_one_iff_eq
algebra.hom
src/algebra/hom/units.lean
[ "algebra.hom.group", "algebra.group.units" ]
[ "div_eq_one_iff_eq", "is_unit" ]
https://github.com/leanprover-community/mathlib
65a1391a0106c9204fe45bc73a039f056558cb83
div_mul_left (h : is_unit b) : b / (a * b) = 1 / a
by rw [div_eq_mul_inv, mul_inv_rev, h.mul_inv_cancel_left, one_div]
lemma
is_unit.div_mul_left
algebra.hom
src/algebra/hom/units.lean
[ "algebra.hom.group", "algebra.group.units" ]
[ "div_eq_mul_inv", "div_mul_left", "is_unit", "mul_inv_rev", "one_div" ]
The `group` version of this lemma is `div_mul_cancel'''`
https://github.com/leanprover-community/mathlib
65a1391a0106c9204fe45bc73a039f056558cb83
mul_div_mul_right (h : is_unit c) (a b : α) : (a * c) / (b * c) = a / b
by simp only [div_eq_mul_inv, mul_inv_rev, mul_assoc, h.mul_inv_cancel_left]
lemma
is_unit.mul_div_mul_right
algebra.hom
src/algebra/hom/units.lean
[ "algebra.hom.group", "algebra.group.units" ]
[ "div_eq_mul_inv", "is_unit", "mul_assoc", "mul_div_mul_right", "mul_inv_rev" ]
https://github.com/leanprover-community/mathlib
65a1391a0106c9204fe45bc73a039f056558cb83
mul_mul_div (a : α) (h : is_unit b) : a * b * (1 / b) = a
by simp [h]
lemma
is_unit.mul_mul_div
algebra.hom
src/algebra/hom/units.lean
[ "algebra.hom.group", "algebra.group.units" ]
[ "is_unit", "mul_mul_div" ]
https://github.com/leanprover-community/mathlib
65a1391a0106c9204fe45bc73a039f056558cb83
div_mul_right (h : is_unit a) (b : α) : a / (a * b) = 1 / b
by rw [mul_comm, h.div_mul_left]
lemma
is_unit.div_mul_right
algebra.hom
src/algebra/hom/units.lean
[ "algebra.hom.group", "algebra.group.units" ]
[ "div_mul_right", "is_unit", "mul_comm" ]
https://github.com/leanprover-community/mathlib
65a1391a0106c9204fe45bc73a039f056558cb83
mul_div_cancel_left (h : is_unit a) (b : α) : a * b / a = b
by rw [mul_comm, h.mul_div_cancel]
lemma
is_unit.mul_div_cancel_left
algebra.hom
src/algebra/hom/units.lean
[ "algebra.hom.group", "algebra.group.units" ]
[ "is_unit", "mul_comm", "mul_div_cancel_left" ]
https://github.com/leanprover-community/mathlib
65a1391a0106c9204fe45bc73a039f056558cb83
mul_div_cancel' (h : is_unit a) (b : α) : a * (b / a) = b
by rw [mul_comm, h.div_mul_cancel]
lemma
is_unit.mul_div_cancel'
algebra.hom
src/algebra/hom/units.lean
[ "algebra.hom.group", "algebra.group.units" ]
[ "is_unit", "mul_comm", "mul_div_cancel'" ]
https://github.com/leanprover-community/mathlib
65a1391a0106c9204fe45bc73a039f056558cb83
mul_div_mul_left (h : is_unit c) (a b : α) : (c * a) / (c * b) = a / b
by rw [mul_comm c, mul_comm c, h.mul_div_mul_right]
lemma
is_unit.mul_div_mul_left
algebra.hom
src/algebra/hom/units.lean
[ "algebra.hom.group", "algebra.group.units" ]
[ "is_unit", "mul_comm", "mul_div_mul_left" ]
https://github.com/leanprover-community/mathlib
65a1391a0106c9204fe45bc73a039f056558cb83
mul_eq_mul_of_div_eq_div (hb : is_unit b) (hd : is_unit d) (a c : α) (h : a / b = c / d) : a * d = c * b
by rw [←mul_one a, ←hb.div_self, ←mul_comm_div, h, div_mul_eq_mul_div, hd.div_mul_cancel]
lemma
is_unit.mul_eq_mul_of_div_eq_div
algebra.hom
src/algebra/hom/units.lean
[ "algebra.hom.group", "algebra.group.units" ]
[ "div_mul_eq_mul_div", "is_unit", "mul_eq_mul_of_div_eq_div" ]
https://github.com/leanprover-community/mathlib
65a1391a0106c9204fe45bc73a039f056558cb83
div_eq_div_iff (hb : is_unit b) (hd : is_unit d) : a / b = c / d ↔ a * d = c * b
by rw [←(hb.mul hd).mul_left_inj, ←mul_assoc, hb.div_mul_cancel, ←mul_assoc, mul_right_comm, hd.div_mul_cancel]
lemma
is_unit.div_eq_div_iff
algebra.hom
src/algebra/hom/units.lean
[ "algebra.hom.group", "algebra.group.units" ]
[ "div_eq_div_iff", "is_unit", "mul_left_inj", "mul_right_comm" ]
https://github.com/leanprover-community/mathlib
65a1391a0106c9204fe45bc73a039f056558cb83
div_div_cancel (h : is_unit a) : a / (a / b) = b
by rw [div_div_eq_mul_div, h.mul_div_cancel_left]
lemma
is_unit.div_div_cancel
algebra.hom
src/algebra/hom/units.lean
[ "algebra.hom.group", "algebra.group.units" ]
[ "div_div_cancel", "div_div_eq_mul_div", "is_unit" ]
https://github.com/leanprover-community/mathlib
65a1391a0106c9204fe45bc73a039f056558cb83
div_div_cancel_left (h : is_unit a) : a / b / a = b⁻¹
by rw [div_eq_mul_inv, div_eq_mul_inv, mul_right_comm, h.mul_inv_cancel, one_mul]
lemma
is_unit.div_div_cancel_left
algebra.hom
src/algebra/hom/units.lean
[ "algebra.hom.group", "algebra.group.units" ]
[ "div_div_cancel_left", "div_eq_mul_inv", "is_unit", "mul_right_comm", "one_mul" ]
https://github.com/leanprover-community/mathlib
65a1391a0106c9204fe45bc73a039f056558cb83
mul_hom.inverse [has_mul M] [has_mul N] (f : M →ₙ* N) (g : N → M) (h₁ : function.left_inverse g f) (h₂ : function.right_inverse g f) : N →ₙ* M
{ to_fun := g, map_mul' := λ x y, calc g (x * y) = g (f (g x) * f (g y)) : by rw [h₂ x, h₂ y] ... = g (f (g x * g y)) : by rw f.map_mul ... = g x * g y : h₁ _, }
def
mul_hom.inverse
algebra.hom.equiv
src/algebra/hom/equiv/basic.lean
[ "algebra.hom.group", "data.fun_like.equiv", "logic.equiv.basic", "data.pi.algebra" ]
[]
Makes a multiplicative inverse from a bijection which preserves multiplication.
https://github.com/leanprover-community/mathlib
65a1391a0106c9204fe45bc73a039f056558cb83
monoid_hom.inverse {A B : Type*} [monoid A] [monoid B] (f : A →* B) (g : B → A) (h₁ : function.left_inverse g f) (h₂ : function.right_inverse g f) : B →* A
{ to_fun := g, map_one' := by rw [← f.map_one, h₁], .. (f : A →ₙ* B).inverse g h₁ h₂, }
def
monoid_hom.inverse
algebra.hom.equiv
src/algebra/hom/equiv/basic.lean
[ "algebra.hom.group", "data.fun_like.equiv", "logic.equiv.basic", "data.pi.algebra" ]
[ "monoid" ]
The inverse of a bijective `monoid_hom` is a `monoid_hom`.
https://github.com/leanprover-community/mathlib
65a1391a0106c9204fe45bc73a039f056558cb83
add_equiv (A B : Type*) [has_add A] [has_add B] extends A ≃ B, add_hom A B
structure
add_equiv
algebra.hom.equiv
src/algebra/hom/equiv/basic.lean
[ "algebra.hom.group", "data.fun_like.equiv", "logic.equiv.basic", "data.pi.algebra" ]
[ "add_hom" ]
add_equiv α β is the type of an equiv α ≃ β which preserves addition.
https://github.com/leanprover-community/mathlib
65a1391a0106c9204fe45bc73a039f056558cb83
add_equiv_class (F A B : Type*) [has_add A] [has_add B] extends equiv_like F A B
(map_add : ∀ (f : F) a b, f (a + b) = f a + f b)
class
add_equiv_class
algebra.hom.equiv
src/algebra/hom/equiv/basic.lean
[ "algebra.hom.group", "data.fun_like.equiv", "logic.equiv.basic", "data.pi.algebra" ]
[ "equiv_like" ]
`add_equiv_class F A B` states that `F` is a type of addition-preserving morphisms. You should extend this class when you extend `add_equiv`.
https://github.com/leanprover-community/mathlib
65a1391a0106c9204fe45bc73a039f056558cb83
mul_equiv (M N : Type*) [has_mul M] [has_mul N] extends M ≃ N, M →ₙ* N
structure
mul_equiv
algebra.hom.equiv
src/algebra/hom/equiv/basic.lean
[ "algebra.hom.group", "data.fun_like.equiv", "logic.equiv.basic", "data.pi.algebra" ]
[]
`mul_equiv α β` is the type of an equiv `α ≃ β` which preserves multiplication.
https://github.com/leanprover-community/mathlib
65a1391a0106c9204fe45bc73a039f056558cb83
mul_equiv_class (F A B : Type*) [has_mul A] [has_mul B] extends equiv_like F A B
(map_mul : ∀ (f : F) a b, f (a * b) = f a * f b)
class
mul_equiv_class
algebra.hom.equiv
src/algebra/hom/equiv/basic.lean
[ "algebra.hom.group", "data.fun_like.equiv", "logic.equiv.basic", "data.pi.algebra" ]
[ "equiv_like", "map_mul" ]
`mul_equiv_class F A B` states that `F` is a type of multiplication-preserving morphisms. You should extend this class when you extend `mul_equiv`.
https://github.com/leanprover-community/mathlib
65a1391a0106c9204fe45bc73a039f056558cb83
to_monoid_with_zero_hom_class {α β : Type*} [mul_zero_one_class α] [mul_zero_one_class β] [mul_equiv_class F α β] : monoid_with_zero_hom_class F α β
{ map_zero := λ e, calc e 0 = e 0 * e (equiv_like.inv e 0) : by rw [←map_mul, zero_mul] ... = 0 : by { convert mul_zero _, exact equiv_like.right_inv e _ } ..mul_equiv_class.monoid_hom_class _ }
instance
mul_equiv_class.to_monoid_with_zero_hom_class
algebra.hom.equiv
src/algebra/hom/equiv/basic.lean
[ "algebra.hom.group", "data.fun_like.equiv", "logic.equiv.basic", "data.pi.algebra" ]
[ "monoid_with_zero_hom_class", "mul_equiv_class", "mul_zero", "mul_zero_one_class", "zero_mul" ]
https://github.com/leanprover-community/mathlib
65a1391a0106c9204fe45bc73a039f056558cb83
map_eq_one_iff {M N} [mul_one_class M] [mul_one_class N] [mul_equiv_class F M N] (h : F) {x : M} : h x = 1 ↔ x = 1
map_eq_one_iff h (equiv_like.injective h)
lemma
mul_equiv_class.map_eq_one_iff
algebra.hom.equiv
src/algebra/hom/equiv/basic.lean
[ "algebra.hom.group", "data.fun_like.equiv", "logic.equiv.basic", "data.pi.algebra" ]
[ "equiv_like.injective", "map_eq_one_iff", "mul_equiv_class", "mul_one_class" ]
https://github.com/leanprover-community/mathlib
65a1391a0106c9204fe45bc73a039f056558cb83
map_ne_one_iff {M N} [mul_one_class M] [mul_one_class N] [mul_equiv_class F M N] (h : F) {x : M} : h x ≠ 1 ↔ x ≠ 1
map_ne_one_iff h (equiv_like.injective h)
lemma
mul_equiv_class.map_ne_one_iff
algebra.hom.equiv
src/algebra/hom/equiv/basic.lean
[ "algebra.hom.group", "data.fun_like.equiv", "logic.equiv.basic", "data.pi.algebra" ]
[ "equiv_like.injective", "map_ne_one_iff", "mul_equiv_class", "mul_one_class" ]
https://github.com/leanprover-community/mathlib
65a1391a0106c9204fe45bc73a039f056558cb83
to_equiv_eq_coe (f : M ≃* N) : f.to_equiv = f
rfl
lemma
mul_equiv.to_equiv_eq_coe
algebra.hom.equiv
src/algebra/hom/equiv/basic.lean
[ "algebra.hom.group", "data.fun_like.equiv", "logic.equiv.basic", "data.pi.algebra" ]
[]
https://github.com/leanprover-community/mathlib
65a1391a0106c9204fe45bc73a039f056558cb83
to_fun_eq_coe {f : M ≃* N} : f.to_fun = f
rfl
lemma
mul_equiv.to_fun_eq_coe
algebra.hom.equiv
src/algebra/hom/equiv/basic.lean
[ "algebra.hom.group", "data.fun_like.equiv", "logic.equiv.basic", "data.pi.algebra" ]
[]
https://github.com/leanprover-community/mathlib
65a1391a0106c9204fe45bc73a039f056558cb83
coe_to_equiv {f : M ≃* N} : ⇑(f : M ≃ N) = f
rfl
lemma
mul_equiv.coe_to_equiv
algebra.hom.equiv
src/algebra/hom/equiv/basic.lean
[ "algebra.hom.group", "data.fun_like.equiv", "logic.equiv.basic", "data.pi.algebra" ]
[]
https://github.com/leanprover-community/mathlib
65a1391a0106c9204fe45bc73a039f056558cb83
coe_to_mul_hom {f : M ≃* N} : ⇑f.to_mul_hom = f
rfl
lemma
mul_equiv.coe_to_mul_hom
algebra.hom.equiv
src/algebra/hom/equiv/basic.lean
[ "algebra.hom.group", "data.fun_like.equiv", "logic.equiv.basic", "data.pi.algebra" ]
[]
https://github.com/leanprover-community/mathlib
65a1391a0106c9204fe45bc73a039f056558cb83
map_mul (f : M ≃* N) : ∀ x y, f (x * y) = f x * f y
map_mul f
lemma
mul_equiv.map_mul
algebra.hom.equiv
src/algebra/hom/equiv/basic.lean
[ "algebra.hom.group", "data.fun_like.equiv", "logic.equiv.basic", "data.pi.algebra" ]
[ "map_mul" ]
A multiplicative isomorphism preserves multiplication.
https://github.com/leanprover-community/mathlib
65a1391a0106c9204fe45bc73a039f056558cb83
mk' (f : M ≃ N) (h : ∀ x y, f (x * y) = f x * f y) : M ≃* N
⟨f.1, f.2, f.3, f.4, h⟩
def
mul_equiv.mk'
algebra.hom.equiv
src/algebra/hom/equiv/basic.lean
[ "algebra.hom.group", "data.fun_like.equiv", "logic.equiv.basic", "data.pi.algebra" ]
[ "mk'" ]
Makes a multiplicative isomorphism from a bijection which preserves multiplication.
https://github.com/leanprover-community/mathlib
65a1391a0106c9204fe45bc73a039f056558cb83
bijective (e : M ≃* N) : function.bijective e
equiv_like.bijective e
lemma
mul_equiv.bijective
algebra.hom.equiv
src/algebra/hom/equiv/basic.lean
[ "algebra.hom.group", "data.fun_like.equiv", "logic.equiv.basic", "data.pi.algebra" ]
[ "equiv_like.bijective" ]
https://github.com/leanprover-community/mathlib
65a1391a0106c9204fe45bc73a039f056558cb83
injective (e : M ≃* N) : function.injective e
equiv_like.injective e
lemma
mul_equiv.injective
algebra.hom.equiv
src/algebra/hom/equiv/basic.lean
[ "algebra.hom.group", "data.fun_like.equiv", "logic.equiv.basic", "data.pi.algebra" ]
[ "equiv_like.injective" ]
https://github.com/leanprover-community/mathlib
65a1391a0106c9204fe45bc73a039f056558cb83
surjective (e : M ≃* N) : function.surjective e
equiv_like.surjective e
lemma
mul_equiv.surjective
algebra.hom.equiv
src/algebra/hom/equiv/basic.lean
[ "algebra.hom.group", "data.fun_like.equiv", "logic.equiv.basic", "data.pi.algebra" ]
[ "equiv_like.surjective" ]
https://github.com/leanprover-community/mathlib
65a1391a0106c9204fe45bc73a039f056558cb83
refl (M : Type*) [has_mul M] : M ≃* M
{ map_mul' := λ _ _, rfl, ..equiv.refl _}
def
mul_equiv.refl
algebra.hom.equiv
src/algebra/hom/equiv/basic.lean
[ "algebra.hom.group", "data.fun_like.equiv", "logic.equiv.basic", "data.pi.algebra" ]
[ "equiv.refl" ]
The identity map is a multiplicative isomorphism.
https://github.com/leanprover-community/mathlib
65a1391a0106c9204fe45bc73a039f056558cb83
symm (h : M ≃* N) : N ≃* M
{ map_mul' := (h.to_mul_hom.inverse h.to_equiv.symm h.left_inv h.right_inv).map_mul, .. h.to_equiv.symm}
def
mul_equiv.symm
algebra.hom.equiv
src/algebra/hom/equiv/basic.lean
[ "algebra.hom.group", "data.fun_like.equiv", "logic.equiv.basic", "data.pi.algebra" ]
[ "map_mul" ]
The inverse of an isomorphism is an isomorphism.
https://github.com/leanprover-community/mathlib
65a1391a0106c9204fe45bc73a039f056558cb83
inv_fun_eq_symm {f : M ≃* N} : f.inv_fun = f.symm
rfl
lemma
mul_equiv.inv_fun_eq_symm
algebra.hom.equiv
src/algebra/hom/equiv/basic.lean
[ "algebra.hom.group", "data.fun_like.equiv", "logic.equiv.basic", "data.pi.algebra" ]
[]
https://github.com/leanprover-community/mathlib
65a1391a0106c9204fe45bc73a039f056558cb83
simps.symm_apply (e : M ≃* N) : N → M
e.symm initialize_simps_projections add_equiv (to_fun → apply, inv_fun → symm_apply) initialize_simps_projections mul_equiv (to_fun → apply, inv_fun → symm_apply)
def
mul_equiv.simps.symm_apply
algebra.hom.equiv
src/algebra/hom/equiv/basic.lean
[ "algebra.hom.group", "data.fun_like.equiv", "logic.equiv.basic", "data.pi.algebra" ]
[ "add_equiv", "inv_fun", "mul_equiv" ]
https://github.com/leanprover-community/mathlib
65a1391a0106c9204fe45bc73a039f056558cb83
to_equiv_symm (f : M ≃* N) : f.symm.to_equiv = f.to_equiv.symm
rfl
theorem
mul_equiv.to_equiv_symm
algebra.hom.equiv
src/algebra/hom/equiv/basic.lean
[ "algebra.hom.group", "data.fun_like.equiv", "logic.equiv.basic", "data.pi.algebra" ]
[]
https://github.com/leanprover-community/mathlib
65a1391a0106c9204fe45bc73a039f056558cb83
coe_mk (f : M → N) (g h₁ h₂ h₃) : ⇑(mul_equiv.mk f g h₁ h₂ h₃) = f
rfl
theorem
mul_equiv.coe_mk
algebra.hom.equiv
src/algebra/hom/equiv/basic.lean
[ "algebra.hom.group", "data.fun_like.equiv", "logic.equiv.basic", "data.pi.algebra" ]
[]
https://github.com/leanprover-community/mathlib
65a1391a0106c9204fe45bc73a039f056558cb83
to_equiv_mk (f : M → N) (g : N → M) (h₁ h₂ h₃) : (mk f g h₁ h₂ h₃).to_equiv = ⟨f, g, h₁, h₂⟩
rfl
lemma
mul_equiv.to_equiv_mk
algebra.hom.equiv
src/algebra/hom/equiv/basic.lean
[ "algebra.hom.group", "data.fun_like.equiv", "logic.equiv.basic", "data.pi.algebra" ]
[]
https://github.com/leanprover-community/mathlib
65a1391a0106c9204fe45bc73a039f056558cb83
symm_symm : ∀ (f : M ≃* N), f.symm.symm = f
| ⟨f, g, h₁, h₂, h₃⟩ := rfl
lemma
mul_equiv.symm_symm
algebra.hom.equiv
src/algebra/hom/equiv/basic.lean
[ "algebra.hom.group", "data.fun_like.equiv", "logic.equiv.basic", "data.pi.algebra" ]
[]
https://github.com/leanprover-community/mathlib
65a1391a0106c9204fe45bc73a039f056558cb83
symm_bijective : function.bijective (symm : (M ≃* N) → (N ≃* M))
equiv.bijective ⟨symm, symm, symm_symm, symm_symm⟩
lemma
mul_equiv.symm_bijective
algebra.hom.equiv
src/algebra/hom/equiv/basic.lean
[ "algebra.hom.group", "data.fun_like.equiv", "logic.equiv.basic", "data.pi.algebra" ]
[ "equiv.bijective" ]
https://github.com/leanprover-community/mathlib
65a1391a0106c9204fe45bc73a039f056558cb83
symm_mk (f : M → N) (g h₁ h₂ h₃) : (mul_equiv.mk f g h₁ h₂ h₃).symm = { to_fun := g, inv_fun := f, ..(mul_equiv.mk f g h₁ h₂ h₃).symm}
rfl
theorem
mul_equiv.symm_mk
algebra.hom.equiv
src/algebra/hom/equiv/basic.lean
[ "algebra.hom.group", "data.fun_like.equiv", "logic.equiv.basic", "data.pi.algebra" ]
[ "inv_fun" ]
https://github.com/leanprover-community/mathlib
65a1391a0106c9204fe45bc73a039f056558cb83
refl_symm : (refl M).symm = refl M
rfl
theorem
mul_equiv.refl_symm
algebra.hom.equiv
src/algebra/hom/equiv/basic.lean
[ "algebra.hom.group", "data.fun_like.equiv", "logic.equiv.basic", "data.pi.algebra" ]
[]
https://github.com/leanprover-community/mathlib
65a1391a0106c9204fe45bc73a039f056558cb83
trans (h1 : M ≃* N) (h2 : N ≃* P) : (M ≃* P)
{ map_mul' := λ x y, show h2 (h1 (x * y)) = h2 (h1 x) * h2 (h1 y), by rw [h1.map_mul, h2.map_mul], ..h1.to_equiv.trans h2.to_equiv }
def
mul_equiv.trans
algebra.hom.equiv
src/algebra/hom/equiv/basic.lean
[ "algebra.hom.group", "data.fun_like.equiv", "logic.equiv.basic", "data.pi.algebra" ]
[]
Transitivity of multiplication-preserving isomorphisms
https://github.com/leanprover-community/mathlib
65a1391a0106c9204fe45bc73a039f056558cb83
apply_symm_apply (e : M ≃* N) (y : N) : e (e.symm y) = y
e.to_equiv.apply_symm_apply y
lemma
mul_equiv.apply_symm_apply
algebra.hom.equiv
src/algebra/hom/equiv/basic.lean
[ "algebra.hom.group", "data.fun_like.equiv", "logic.equiv.basic", "data.pi.algebra" ]
[]
`e.symm` is a right inverse of `e`, written as `e (e.symm y) = y`.
https://github.com/leanprover-community/mathlib
65a1391a0106c9204fe45bc73a039f056558cb83
symm_apply_apply (e : M ≃* N) (x : M) : e.symm (e x) = x
e.to_equiv.symm_apply_apply x
lemma
mul_equiv.symm_apply_apply
algebra.hom.equiv
src/algebra/hom/equiv/basic.lean
[ "algebra.hom.group", "data.fun_like.equiv", "logic.equiv.basic", "data.pi.algebra" ]
[]
`e.symm` is a left inverse of `e`, written as `e.symm (e y) = y`.
https://github.com/leanprover-community/mathlib
65a1391a0106c9204fe45bc73a039f056558cb83
symm_comp_self (e : M ≃* N) : e.symm ∘ e = id
funext e.symm_apply_apply
theorem
mul_equiv.symm_comp_self
algebra.hom.equiv
src/algebra/hom/equiv/basic.lean
[ "algebra.hom.group", "data.fun_like.equiv", "logic.equiv.basic", "data.pi.algebra" ]
[]
https://github.com/leanprover-community/mathlib
65a1391a0106c9204fe45bc73a039f056558cb83
self_comp_symm (e : M ≃* N) : e ∘ e.symm = id
funext e.apply_symm_apply
theorem
mul_equiv.self_comp_symm
algebra.hom.equiv
src/algebra/hom/equiv/basic.lean
[ "algebra.hom.group", "data.fun_like.equiv", "logic.equiv.basic", "data.pi.algebra" ]
[]
https://github.com/leanprover-community/mathlib
65a1391a0106c9204fe45bc73a039f056558cb83
coe_refl : ⇑(refl M) = id
rfl
theorem
mul_equiv.coe_refl
algebra.hom.equiv
src/algebra/hom/equiv/basic.lean
[ "algebra.hom.group", "data.fun_like.equiv", "logic.equiv.basic", "data.pi.algebra" ]
[]
https://github.com/leanprover-community/mathlib
65a1391a0106c9204fe45bc73a039f056558cb83
refl_apply (m : M) : refl M m = m
rfl
theorem
mul_equiv.refl_apply
algebra.hom.equiv
src/algebra/hom/equiv/basic.lean
[ "algebra.hom.group", "data.fun_like.equiv", "logic.equiv.basic", "data.pi.algebra" ]
[]
https://github.com/leanprover-community/mathlib
65a1391a0106c9204fe45bc73a039f056558cb83
coe_trans (e₁ : M ≃* N) (e₂ : N ≃* P) : ⇑(e₁.trans e₂) = e₂ ∘ e₁
rfl
theorem
mul_equiv.coe_trans
algebra.hom.equiv
src/algebra/hom/equiv/basic.lean
[ "algebra.hom.group", "data.fun_like.equiv", "logic.equiv.basic", "data.pi.algebra" ]
[]
https://github.com/leanprover-community/mathlib
65a1391a0106c9204fe45bc73a039f056558cb83
trans_apply (e₁ : M ≃* N) (e₂ : N ≃* P) (m : M) : e₁.trans e₂ m = e₂ (e₁ m)
rfl
theorem
mul_equiv.trans_apply
algebra.hom.equiv
src/algebra/hom/equiv/basic.lean
[ "algebra.hom.group", "data.fun_like.equiv", "logic.equiv.basic", "data.pi.algebra" ]
[]
https://github.com/leanprover-community/mathlib
65a1391a0106c9204fe45bc73a039f056558cb83
symm_trans_apply (e₁ : M ≃* N) (e₂ : N ≃* P) (p : P) : (e₁.trans e₂).symm p = e₁.symm (e₂.symm p)
rfl
theorem
mul_equiv.symm_trans_apply
algebra.hom.equiv
src/algebra/hom/equiv/basic.lean
[ "algebra.hom.group", "data.fun_like.equiv", "logic.equiv.basic", "data.pi.algebra" ]
[]
https://github.com/leanprover-community/mathlib
65a1391a0106c9204fe45bc73a039f056558cb83
apply_eq_iff_eq (e : M ≃* N) {x y : M} : e x = e y ↔ x = y
e.injective.eq_iff
theorem
mul_equiv.apply_eq_iff_eq
algebra.hom.equiv
src/algebra/hom/equiv/basic.lean
[ "algebra.hom.group", "data.fun_like.equiv", "logic.equiv.basic", "data.pi.algebra" ]
[]
https://github.com/leanprover-community/mathlib
65a1391a0106c9204fe45bc73a039f056558cb83
apply_eq_iff_symm_apply (e : M ≃* N) {x : M} {y : N} : e x = y ↔ x = e.symm y
e.to_equiv.apply_eq_iff_eq_symm_apply
lemma
mul_equiv.apply_eq_iff_symm_apply
algebra.hom.equiv
src/algebra/hom/equiv/basic.lean
[ "algebra.hom.group", "data.fun_like.equiv", "logic.equiv.basic", "data.pi.algebra" ]
[]
https://github.com/leanprover-community/mathlib
65a1391a0106c9204fe45bc73a039f056558cb83
symm_apply_eq (e : M ≃* N) {x y} : e.symm x = y ↔ x = e y
e.to_equiv.symm_apply_eq
lemma
mul_equiv.symm_apply_eq
algebra.hom.equiv
src/algebra/hom/equiv/basic.lean
[ "algebra.hom.group", "data.fun_like.equiv", "logic.equiv.basic", "data.pi.algebra" ]
[]
https://github.com/leanprover-community/mathlib
65a1391a0106c9204fe45bc73a039f056558cb83
eq_symm_apply (e : M ≃* N) {x y} : y = e.symm x ↔ e y = x
e.to_equiv.eq_symm_apply
lemma
mul_equiv.eq_symm_apply
algebra.hom.equiv
src/algebra/hom/equiv/basic.lean
[ "algebra.hom.group", "data.fun_like.equiv", "logic.equiv.basic", "data.pi.algebra" ]
[]
https://github.com/leanprover-community/mathlib
65a1391a0106c9204fe45bc73a039f056558cb83
eq_comp_symm {α : Type*} (e : M ≃* N) (f : N → α) (g : M → α) : f = g ∘ e.symm ↔ f ∘ e = g
e.to_equiv.eq_comp_symm f g
lemma
mul_equiv.eq_comp_symm
algebra.hom.equiv
src/algebra/hom/equiv/basic.lean
[ "algebra.hom.group", "data.fun_like.equiv", "logic.equiv.basic", "data.pi.algebra" ]
[]
https://github.com/leanprover-community/mathlib
65a1391a0106c9204fe45bc73a039f056558cb83
comp_symm_eq {α : Type*} (e : M ≃* N) (f : N → α) (g : M → α) : g ∘ e.symm = f ↔ g = f ∘ e
e.to_equiv.comp_symm_eq f g
lemma
mul_equiv.comp_symm_eq
algebra.hom.equiv
src/algebra/hom/equiv/basic.lean
[ "algebra.hom.group", "data.fun_like.equiv", "logic.equiv.basic", "data.pi.algebra" ]
[]
https://github.com/leanprover-community/mathlib
65a1391a0106c9204fe45bc73a039f056558cb83
eq_symm_comp {α : Type*} (e : M ≃* N) (f : α → M) (g : α → N) : f = e.symm ∘ g ↔ e ∘ f = g
e.to_equiv.eq_symm_comp f g
lemma
mul_equiv.eq_symm_comp
algebra.hom.equiv
src/algebra/hom/equiv/basic.lean
[ "algebra.hom.group", "data.fun_like.equiv", "logic.equiv.basic", "data.pi.algebra" ]
[]
https://github.com/leanprover-community/mathlib
65a1391a0106c9204fe45bc73a039f056558cb83
symm_comp_eq {α : Type*} (e : M ≃* N) (f : α → M) (g : α → N) : e.symm ∘ g = f ↔ g = e ∘ f
e.to_equiv.symm_comp_eq f g
lemma
mul_equiv.symm_comp_eq
algebra.hom.equiv
src/algebra/hom/equiv/basic.lean
[ "algebra.hom.group", "data.fun_like.equiv", "logic.equiv.basic", "data.pi.algebra" ]
[]
https://github.com/leanprover-community/mathlib
65a1391a0106c9204fe45bc73a039f056558cb83
symm_trans_self (e : M ≃* N) : e.symm.trans e = refl N
fun_like.ext _ _ e.apply_symm_apply
theorem
mul_equiv.symm_trans_self
algebra.hom.equiv
src/algebra/hom/equiv/basic.lean
[ "algebra.hom.group", "data.fun_like.equiv", "logic.equiv.basic", "data.pi.algebra" ]
[ "fun_like.ext" ]
https://github.com/leanprover-community/mathlib
65a1391a0106c9204fe45bc73a039f056558cb83
self_trans_symm (e : M ≃* N) : e.trans e.symm = refl M
fun_like.ext _ _ e.symm_apply_apply
theorem
mul_equiv.self_trans_symm
algebra.hom.equiv
src/algebra/hom/equiv/basic.lean
[ "algebra.hom.group", "data.fun_like.equiv", "logic.equiv.basic", "data.pi.algebra" ]
[ "fun_like.ext" ]
https://github.com/leanprover-community/mathlib
65a1391a0106c9204fe45bc73a039f056558cb83
coe_monoid_hom_refl {M} [mul_one_class M] : (refl M : M →* M) = monoid_hom.id M
rfl
lemma
mul_equiv.coe_monoid_hom_refl
algebra.hom.equiv
src/algebra/hom/equiv/basic.lean
[ "algebra.hom.group", "data.fun_like.equiv", "logic.equiv.basic", "data.pi.algebra" ]
[ "monoid_hom.id", "mul_one_class" ]
https://github.com/leanprover-community/mathlib
65a1391a0106c9204fe45bc73a039f056558cb83
coe_monoid_hom_trans {M N P} [mul_one_class M] [mul_one_class N] [mul_one_class P] (e₁ : M ≃* N) (e₂ : N ≃* P) : (e₁.trans e₂ : M →* P) = (e₂ : N →* P).comp ↑e₁
rfl
lemma
mul_equiv.coe_monoid_hom_trans
algebra.hom.equiv
src/algebra/hom/equiv/basic.lean
[ "algebra.hom.group", "data.fun_like.equiv", "logic.equiv.basic", "data.pi.algebra" ]
[ "mul_one_class" ]
https://github.com/leanprover-community/mathlib
65a1391a0106c9204fe45bc73a039f056558cb83
ext {f g : mul_equiv M N} (h : ∀ x, f x = g x) : f = g
fun_like.ext f g h
lemma
mul_equiv.ext
algebra.hom.equiv
src/algebra/hom/equiv/basic.lean
[ "algebra.hom.group", "data.fun_like.equiv", "logic.equiv.basic", "data.pi.algebra" ]
[ "fun_like.ext", "mul_equiv" ]
Two multiplicative isomorphisms agree if they are defined by the same underlying function.
https://github.com/leanprover-community/mathlib
65a1391a0106c9204fe45bc73a039f056558cb83
ext_iff {f g : mul_equiv M N} : f = g ↔ ∀ x, f x = g x
fun_like.ext_iff
lemma
mul_equiv.ext_iff
algebra.hom.equiv
src/algebra/hom/equiv/basic.lean
[ "algebra.hom.group", "data.fun_like.equiv", "logic.equiv.basic", "data.pi.algebra" ]
[ "fun_like.ext_iff", "mul_equiv" ]
https://github.com/leanprover-community/mathlib
65a1391a0106c9204fe45bc73a039f056558cb83
mk_coe (e : M ≃* N) (e' h₁ h₂ h₃) : (⟨e, e', h₁, h₂, h₃⟩ : M ≃* N) = e
ext $ λ _, rfl
lemma
mul_equiv.mk_coe
algebra.hom.equiv
src/algebra/hom/equiv/basic.lean
[ "algebra.hom.group", "data.fun_like.equiv", "logic.equiv.basic", "data.pi.algebra" ]
[]
https://github.com/leanprover-community/mathlib
65a1391a0106c9204fe45bc73a039f056558cb83
mk_coe' (e : M ≃* N) (f h₁ h₂ h₃) : (mul_equiv.mk f ⇑e h₁ h₂ h₃ : N ≃* M) = e.symm
symm_bijective.injective $ ext $ λ x, rfl
lemma
mul_equiv.mk_coe'
algebra.hom.equiv
src/algebra/hom/equiv/basic.lean
[ "algebra.hom.group", "data.fun_like.equiv", "logic.equiv.basic", "data.pi.algebra" ]
[]
https://github.com/leanprover-community/mathlib
65a1391a0106c9204fe45bc73a039f056558cb83
congr_arg {f : mul_equiv M N} {x x' : M} : x = x' → f x = f x'
fun_like.congr_arg f
lemma
mul_equiv.congr_arg
algebra.hom.equiv
src/algebra/hom/equiv/basic.lean
[ "algebra.hom.group", "data.fun_like.equiv", "logic.equiv.basic", "data.pi.algebra" ]
[ "fun_like.congr_arg", "mul_equiv" ]
https://github.com/leanprover-community/mathlib
65a1391a0106c9204fe45bc73a039f056558cb83
congr_fun {f g : mul_equiv M N} (h : f = g) (x : M) : f x = g x
fun_like.congr_fun h x
lemma
mul_equiv.congr_fun
algebra.hom.equiv
src/algebra/hom/equiv/basic.lean
[ "algebra.hom.group", "data.fun_like.equiv", "logic.equiv.basic", "data.pi.algebra" ]
[ "fun_like.congr_fun", "mul_equiv" ]
https://github.com/leanprover-community/mathlib
65a1391a0106c9204fe45bc73a039f056558cb83
mul_equiv_of_unique {M N} [unique M] [unique N] [has_mul M] [has_mul N] : M ≃* N
{ map_mul' := λ _ _, subsingleton.elim _ _, ..equiv.equiv_of_unique M N }
def
mul_equiv.mul_equiv_of_unique
algebra.hom.equiv
src/algebra/hom/equiv/basic.lean
[ "algebra.hom.group", "data.fun_like.equiv", "logic.equiv.basic", "data.pi.algebra" ]
[ "equiv.equiv_of_unique", "unique" ]
The `mul_equiv` between two monoids with a unique element.
https://github.com/leanprover-community/mathlib
65a1391a0106c9204fe45bc73a039f056558cb83
map_one {M N} [mul_one_class M] [mul_one_class N] (h : M ≃* N) : h 1 = 1
map_one h
lemma
mul_equiv.map_one
algebra.hom.equiv
src/algebra/hom/equiv/basic.lean
[ "algebra.hom.group", "data.fun_like.equiv", "logic.equiv.basic", "data.pi.algebra" ]
[ "map_one", "mul_one_class" ]
A multiplicative isomorphism of monoids sends `1` to `1` (and is hence a monoid isomorphism).
https://github.com/leanprover-community/mathlib
65a1391a0106c9204fe45bc73a039f056558cb83
map_eq_one_iff {M N} [mul_one_class M] [mul_one_class N] (h : M ≃* N) {x : M} : h x = 1 ↔ x = 1
mul_equiv_class.map_eq_one_iff h
lemma
mul_equiv.map_eq_one_iff
algebra.hom.equiv
src/algebra/hom/equiv/basic.lean
[ "algebra.hom.group", "data.fun_like.equiv", "logic.equiv.basic", "data.pi.algebra" ]
[ "map_eq_one_iff", "mul_equiv_class.map_eq_one_iff", "mul_one_class" ]
https://github.com/leanprover-community/mathlib
65a1391a0106c9204fe45bc73a039f056558cb83
map_ne_one_iff {M N} [mul_one_class M] [mul_one_class N] (h : M ≃* N) {x : M} : h x ≠ 1 ↔ x ≠ 1
mul_equiv_class.map_ne_one_iff h
lemma
mul_equiv.map_ne_one_iff
algebra.hom.equiv
src/algebra/hom/equiv/basic.lean
[ "algebra.hom.group", "data.fun_like.equiv", "logic.equiv.basic", "data.pi.algebra" ]
[ "map_ne_one_iff", "mul_equiv_class.map_ne_one_iff", "mul_one_class" ]
https://github.com/leanprover-community/mathlib
65a1391a0106c9204fe45bc73a039f056558cb83
of_bijective {M N F} [has_mul M] [has_mul N] [mul_hom_class F M N] (f : F) (hf : function.bijective f) : M ≃* N
{ map_mul' := map_mul f, ..equiv.of_bijective f hf }
def
mul_equiv.of_bijective
algebra.hom.equiv
src/algebra/hom/equiv/basic.lean
[ "algebra.hom.group", "data.fun_like.equiv", "logic.equiv.basic", "data.pi.algebra" ]
[ "equiv.of_bijective", "map_mul", "mul_hom_class" ]
A bijective `semigroup` homomorphism is an isomorphism
https://github.com/leanprover-community/mathlib
65a1391a0106c9204fe45bc73a039f056558cb83
of_bijective_apply_symm_apply {M N} [mul_one_class M] [mul_one_class N] {n : N} (f : M →* N) (hf : function.bijective f) : f ((equiv.of_bijective f hf).symm n) = n
(mul_equiv.of_bijective f hf).apply_symm_apply n
lemma
mul_equiv.of_bijective_apply_symm_apply
algebra.hom.equiv
src/algebra/hom/equiv/basic.lean
[ "algebra.hom.group", "data.fun_like.equiv", "logic.equiv.basic", "data.pi.algebra" ]
[ "equiv.of_bijective", "mul_equiv.of_bijective", "mul_one_class" ]
https://github.com/leanprover-community/mathlib
65a1391a0106c9204fe45bc73a039f056558cb83
to_monoid_hom {M N} [mul_one_class M] [mul_one_class N] (h : M ≃* N) : (M →* N)
{ map_one' := h.map_one, .. h }
def
mul_equiv.to_monoid_hom
algebra.hom.equiv
src/algebra/hom/equiv/basic.lean
[ "algebra.hom.group", "data.fun_like.equiv", "logic.equiv.basic", "data.pi.algebra" ]
[ "mul_one_class" ]
Extract the forward direction of a multiplicative equivalence as a multiplication-preserving function.
https://github.com/leanprover-community/mathlib
65a1391a0106c9204fe45bc73a039f056558cb83
coe_to_monoid_hom {M N} [mul_one_class M] [mul_one_class N] (e : M ≃* N) : ⇑e.to_monoid_hom = e
rfl
lemma
mul_equiv.coe_to_monoid_hom
algebra.hom.equiv
src/algebra/hom/equiv/basic.lean
[ "algebra.hom.group", "data.fun_like.equiv", "logic.equiv.basic", "data.pi.algebra" ]
[ "mul_one_class" ]
https://github.com/leanprover-community/mathlib
65a1391a0106c9204fe45bc73a039f056558cb83
to_monoid_hom_injective {M N} [mul_one_class M] [mul_one_class N] : function.injective (to_monoid_hom : (M ≃* N) → M →* N)
λ f g h, mul_equiv.ext (monoid_hom.ext_iff.1 h)
lemma
mul_equiv.to_monoid_hom_injective
algebra.hom.equiv
src/algebra/hom/equiv/basic.lean
[ "algebra.hom.group", "data.fun_like.equiv", "logic.equiv.basic", "data.pi.algebra" ]
[ "mul_equiv.ext", "mul_one_class" ]
https://github.com/leanprover-community/mathlib
65a1391a0106c9204fe45bc73a039f056558cb83
arrow_congr {M N P Q : Type*} [has_mul P] [has_mul Q] (f : M ≃ N) (g : P ≃* Q) : (M → P) ≃* (N → Q)
{ to_fun := λ h n, g (h (f.symm n)), inv_fun := λ k m, g.symm (k (f m)), left_inv := λ h, by { ext, simp, }, right_inv := λ k, by { ext, simp, }, map_mul' := λ h k, by { ext, simp, }, }
def
mul_equiv.arrow_congr
algebra.hom.equiv
src/algebra/hom/equiv/basic.lean
[ "algebra.hom.group", "data.fun_like.equiv", "logic.equiv.basic", "data.pi.algebra" ]
[ "inv_fun" ]
A multiplicative analogue of `equiv.arrow_congr`, where the equivalence between the targets is multiplicative.
https://github.com/leanprover-community/mathlib
65a1391a0106c9204fe45bc73a039f056558cb83
monoid_hom_congr {M N P Q} [mul_one_class M] [mul_one_class N] [comm_monoid P] [comm_monoid Q] (f : M ≃* N) (g : P ≃* Q) : (M →* P) ≃* (N →* Q)
{ to_fun := λ h, g.to_monoid_hom.comp (h.comp f.symm.to_monoid_hom), inv_fun := λ k, g.symm.to_monoid_hom.comp (k.comp f.to_monoid_hom), left_inv := λ h, by { ext, simp, }, right_inv := λ k, by { ext, simp, }, map_mul' := λ h k, by { ext, simp, }, }
def
mul_equiv.monoid_hom_congr
algebra.hom.equiv
src/algebra/hom/equiv/basic.lean
[ "algebra.hom.group", "data.fun_like.equiv", "logic.equiv.basic", "data.pi.algebra" ]
[ "comm_monoid", "inv_fun", "mul_one_class" ]
A multiplicative analogue of `equiv.arrow_congr`, for multiplicative maps from a monoid to a commutative monoid.
https://github.com/leanprover-community/mathlib
65a1391a0106c9204fe45bc73a039f056558cb83
Pi_congr_right {η : Type*} {Ms Ns : η → Type*} [Π j, has_mul (Ms j)] [Π j, has_mul (Ns j)] (es : ∀ j, Ms j ≃* Ns j) : (Π j, Ms j) ≃* (Π j, Ns j)
{ to_fun := λ x j, es j (x j), inv_fun := λ x j, (es j).symm (x j), map_mul' := λ x y, funext $ λ j, (es j).map_mul (x j) (y j), .. equiv.Pi_congr_right (λ j, (es j).to_equiv) }
def
mul_equiv.Pi_congr_right
algebra.hom.equiv
src/algebra/hom/equiv/basic.lean
[ "algebra.hom.group", "data.fun_like.equiv", "logic.equiv.basic", "data.pi.algebra" ]
[ "equiv.Pi_congr_right", "inv_fun", "map_mul" ]
A family of multiplicative equivalences `Π j, (Ms j ≃* Ns j)` generates a multiplicative equivalence between `Π j, Ms j` and `Π j, Ns j`. This is the `mul_equiv` version of `equiv.Pi_congr_right`, and the dependent version of `mul_equiv.arrow_congr`.
https://github.com/leanprover-community/mathlib
65a1391a0106c9204fe45bc73a039f056558cb83
Pi_congr_right_refl {η : Type*} {Ms : η → Type*} [Π j, has_mul (Ms j)] : Pi_congr_right (λ j, mul_equiv.refl (Ms j)) = mul_equiv.refl _
rfl
lemma
mul_equiv.Pi_congr_right_refl
algebra.hom.equiv
src/algebra/hom/equiv/basic.lean
[ "algebra.hom.group", "data.fun_like.equiv", "logic.equiv.basic", "data.pi.algebra" ]
[ "mul_equiv.refl" ]
https://github.com/leanprover-community/mathlib
65a1391a0106c9204fe45bc73a039f056558cb83
Pi_congr_right_symm {η : Type*} {Ms Ns : η → Type*} [Π j, has_mul (Ms j)] [Π j, has_mul (Ns j)] (es : ∀ j, Ms j ≃* Ns j) : (Pi_congr_right es).symm = (Pi_congr_right $ λ i, (es i).symm)
rfl
lemma
mul_equiv.Pi_congr_right_symm
algebra.hom.equiv
src/algebra/hom/equiv/basic.lean
[ "algebra.hom.group", "data.fun_like.equiv", "logic.equiv.basic", "data.pi.algebra" ]
[]
https://github.com/leanprover-community/mathlib
65a1391a0106c9204fe45bc73a039f056558cb83
Pi_congr_right_trans {η : Type*} {Ms Ns Ps : η → Type*} [Π j, has_mul (Ms j)] [Π j, has_mul (Ns j)] [Π j, has_mul (Ps j)] (es : ∀ j, Ms j ≃* Ns j) (fs : ∀ j, Ns j ≃* Ps j) : (Pi_congr_right es).trans (Pi_congr_right fs) = (Pi_congr_right $ λ i, (es i).trans (fs i))
rfl
lemma
mul_equiv.Pi_congr_right_trans
algebra.hom.equiv
src/algebra/hom/equiv/basic.lean
[ "algebra.hom.group", "data.fun_like.equiv", "logic.equiv.basic", "data.pi.algebra" ]
[]
https://github.com/leanprover-community/mathlib
65a1391a0106c9204fe45bc73a039f056558cb83
Pi_subsingleton {ι : Type*} (M : ι → Type*) [Π j, has_mul (M j)] [subsingleton ι] (i : ι) : (Π j, M j) ≃* M i
{ map_mul' := λ f1 f2, pi.mul_apply _ _ _, ..equiv.Pi_subsingleton M i }
def
mul_equiv.Pi_subsingleton
algebra.hom.equiv
src/algebra/hom/equiv/basic.lean
[ "algebra.hom.group", "data.fun_like.equiv", "logic.equiv.basic", "data.pi.algebra" ]
[ "equiv.Pi_subsingleton", "pi.mul_apply" ]
A family indexed by a nonempty subsingleton type is equivalent to the element at the single index.
https://github.com/leanprover-community/mathlib
65a1391a0106c9204fe45bc73a039f056558cb83
map_inv [group G] [division_monoid H] (h : G ≃* H) (x : G) : h x⁻¹ = (h x)⁻¹
map_inv h x
lemma
mul_equiv.map_inv
algebra.hom.equiv
src/algebra/hom/equiv/basic.lean
[ "algebra.hom.group", "data.fun_like.equiv", "logic.equiv.basic", "data.pi.algebra" ]
[ "division_monoid", "group", "map_inv" ]
A multiplicative equivalence of groups preserves inversion.
https://github.com/leanprover-community/mathlib
65a1391a0106c9204fe45bc73a039f056558cb83
map_div [group G] [division_monoid H] (h : G ≃* H) (x y : G) : h (x / y) = h x / h y
map_div h x y
lemma
mul_equiv.map_div
algebra.hom.equiv
src/algebra/hom/equiv/basic.lean
[ "algebra.hom.group", "data.fun_like.equiv", "logic.equiv.basic", "data.pi.algebra" ]
[ "division_monoid", "group", "map_div" ]
A multiplicative equivalence of groups preserves division.
https://github.com/leanprover-community/mathlib
65a1391a0106c9204fe45bc73a039f056558cb83
mul_hom.to_mul_equiv [has_mul M] [has_mul N] (f : M →ₙ* N) (g : N →ₙ* M) (h₁ : g.comp f = mul_hom.id _) (h₂ : f.comp g = mul_hom.id _) : M ≃* N
{ to_fun := f, inv_fun := g, left_inv := mul_hom.congr_fun h₁, right_inv := mul_hom.congr_fun h₂, map_mul' := f.map_mul }
def
mul_hom.to_mul_equiv
algebra.hom.equiv
src/algebra/hom/equiv/basic.lean
[ "algebra.hom.group", "data.fun_like.equiv", "logic.equiv.basic", "data.pi.algebra" ]
[ "inv_fun", "mul_hom.congr_fun", "mul_hom.id" ]
Given a pair of multiplicative homomorphisms `f`, `g` such that `g.comp f = id` and `f.comp g = id`, returns an multiplicative equivalence with `to_fun = f` and `inv_fun = g`. This constructor is useful if the underlying type(s) have specialized `ext` lemmas for multiplicative homomorphisms.
https://github.com/leanprover-community/mathlib
65a1391a0106c9204fe45bc73a039f056558cb83
monoid_hom.to_mul_equiv [mul_one_class M] [mul_one_class N] (f : M →* N) (g : N →* M) (h₁ : g.comp f = monoid_hom.id _) (h₂ : f.comp g = monoid_hom.id _) : M ≃* N
{ to_fun := f, inv_fun := g, left_inv := monoid_hom.congr_fun h₁, right_inv := monoid_hom.congr_fun h₂, map_mul' := f.map_mul }
def
monoid_hom.to_mul_equiv
algebra.hom.equiv
src/algebra/hom/equiv/basic.lean
[ "algebra.hom.group", "data.fun_like.equiv", "logic.equiv.basic", "data.pi.algebra" ]
[ "inv_fun", "monoid_hom.congr_fun", "monoid_hom.id", "mul_one_class" ]
Given a pair of monoid homomorphisms `f`, `g` such that `g.comp f = id` and `f.comp g = id`, returns an multiplicative equivalence with `to_fun = f` and `inv_fun = g`. This constructor is useful if the underlying type(s) have specialized `ext` lemmas for monoid homomorphisms.
https://github.com/leanprover-community/mathlib
65a1391a0106c9204fe45bc73a039f056558cb83
inv : perm G
inv_involutive.to_perm _
def
equiv.inv
algebra.hom.equiv
src/algebra/hom/equiv/basic.lean
[ "algebra.hom.group", "data.fun_like.equiv", "logic.equiv.basic", "data.pi.algebra" ]
[]
Inversion on a `group` or `group_with_zero` is a permutation of the underlying type.
https://github.com/leanprover-community/mathlib
65a1391a0106c9204fe45bc73a039f056558cb83
inv_symm : (equiv.inv G).symm = equiv.inv G
rfl
lemma
equiv.inv_symm
algebra.hom.equiv
src/algebra/hom/equiv/basic.lean
[ "algebra.hom.group", "data.fun_like.equiv", "logic.equiv.basic", "data.pi.algebra" ]
[ "equiv.inv" ]
https://github.com/leanprover-community/mathlib
65a1391a0106c9204fe45bc73a039f056558cb83
add_equiv.to_multiplicative [add_zero_class G] [add_zero_class H] : (G ≃+ H) ≃ (multiplicative G ≃* multiplicative H)
{ to_fun := λ f, ⟨f.to_add_monoid_hom.to_multiplicative, f.symm.to_add_monoid_hom.to_multiplicative, f.3, f.4, f.5⟩, inv_fun := λ f, ⟨f.to_monoid_hom, f.symm.to_monoid_hom, f.3, f.4, f.5⟩, left_inv := λ x, by { ext, refl, }, right_inv := λ x, by { ext, refl, }, }
def
add_equiv.to_multiplicative
algebra.hom.equiv
src/algebra/hom/equiv/type_tags.lean
[ "algebra.hom.equiv.basic", "algebra.group.type_tags" ]
[ "add_zero_class", "inv_fun", "multiplicative" ]
Reinterpret `G ≃+ H` as `multiplicative G ≃* multiplicative H`.
https://github.com/leanprover-community/mathlib
65a1391a0106c9204fe45bc73a039f056558cb83
mul_equiv.to_additive [mul_one_class G] [mul_one_class H] : (G ≃* H) ≃ (additive G ≃+ additive H)
{ to_fun := λ f, ⟨f.to_monoid_hom.to_additive, f.symm.to_monoid_hom.to_additive, f.3, f.4, f.5⟩, inv_fun := λ f, ⟨f.to_add_monoid_hom, f.symm.to_add_monoid_hom, f.3, f.4, f.5⟩, left_inv := λ x, by { ext, refl, }, right_inv := λ x, by { ext, refl, }, }
def
mul_equiv.to_additive
algebra.hom.equiv
src/algebra/hom/equiv/type_tags.lean
[ "algebra.hom.equiv.basic", "algebra.group.type_tags" ]
[ "additive", "inv_fun", "mul_one_class" ]
Reinterpret `G ≃* H` as `additive G ≃+ additive H`.
https://github.com/leanprover-community/mathlib
65a1391a0106c9204fe45bc73a039f056558cb83
add_equiv.to_multiplicative' [mul_one_class G] [add_zero_class H] : (additive G ≃+ H) ≃ (G ≃* multiplicative H)
{ to_fun := λ f, ⟨f.to_add_monoid_hom.to_multiplicative', f.symm.to_add_monoid_hom.to_multiplicative'', f.3, f.4, f.5⟩, inv_fun := λ f, ⟨f.to_monoid_hom, f.symm.to_monoid_hom, f.3, f.4, f.5⟩, left_inv := λ x, by { ext, refl, }, right_inv := λ x, by { ext, refl, }, }
def
add_equiv.to_multiplicative'
algebra.hom.equiv
src/algebra/hom/equiv/type_tags.lean
[ "algebra.hom.equiv.basic", "algebra.group.type_tags" ]
[ "add_zero_class", "additive", "inv_fun", "mul_one_class", "multiplicative" ]
Reinterpret `additive G ≃+ H` as `G ≃* multiplicative H`.
https://github.com/leanprover-community/mathlib
65a1391a0106c9204fe45bc73a039f056558cb83
mul_equiv.to_additive' [mul_one_class G] [add_zero_class H] : (G ≃* multiplicative H) ≃ (additive G ≃+ H)
add_equiv.to_multiplicative'.symm
def
mul_equiv.to_additive'
algebra.hom.equiv
src/algebra/hom/equiv/type_tags.lean
[ "algebra.hom.equiv.basic", "algebra.group.type_tags" ]
[ "add_zero_class", "additive", "mul_one_class", "multiplicative" ]
Reinterpret `G ≃* multiplicative H` as `additive G ≃+ H` as.
https://github.com/leanprover-community/mathlib
65a1391a0106c9204fe45bc73a039f056558cb83
add_equiv.to_multiplicative'' [add_zero_class G] [mul_one_class H] : (G ≃+ additive H) ≃ (multiplicative G ≃* H)
{ to_fun := λ f, ⟨f.to_add_monoid_hom.to_multiplicative'', f.symm.to_add_monoid_hom.to_multiplicative', f.3, f.4, f.5⟩, inv_fun := λ f, ⟨f.to_monoid_hom, f.symm.to_monoid_hom, f.3, f.4, f.5⟩, left_inv := λ x, by { ext, refl, }, right_inv := λ x, by { ext, refl, }, }
def
add_equiv.to_multiplicative''
algebra.hom.equiv
src/algebra/hom/equiv/type_tags.lean
[ "algebra.hom.equiv.basic", "algebra.group.type_tags" ]
[ "add_zero_class", "additive", "inv_fun", "mul_one_class", "multiplicative" ]
Reinterpret `G ≃+ additive H` as `multiplicative G ≃* H`.
https://github.com/leanprover-community/mathlib
65a1391a0106c9204fe45bc73a039f056558cb83
mul_equiv.to_additive'' [add_zero_class G] [mul_one_class H] : (multiplicative G ≃* H) ≃ (G ≃+ additive H)
add_equiv.to_multiplicative''.symm
def
mul_equiv.to_additive''
algebra.hom.equiv
src/algebra/hom/equiv/type_tags.lean
[ "algebra.hom.equiv.basic", "algebra.group.type_tags" ]
[ "add_zero_class", "additive", "mul_one_class", "multiplicative" ]
Reinterpret `multiplicative G ≃* H` as `G ≃+ additive H` as.
https://github.com/leanprover-community/mathlib
65a1391a0106c9204fe45bc73a039f056558cb83
add_equiv.additive_multiplicative [add_zero_class G] : additive (multiplicative G) ≃+ G
mul_equiv.to_additive'' (mul_equiv.refl (multiplicative G))
def
add_equiv.additive_multiplicative
algebra.hom.equiv
src/algebra/hom/equiv/type_tags.lean
[ "algebra.hom.equiv.basic", "algebra.group.type_tags" ]
[ "add_zero_class", "additive", "mul_equiv.refl", "mul_equiv.to_additive''", "multiplicative" ]
`additive (multiplicative G)` is just `G`.
https://github.com/leanprover-community/mathlib
65a1391a0106c9204fe45bc73a039f056558cb83