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unop_mul [Mul α] (x y : αᵐᵒᵖ) : unop (x * y) = unop y * unop x
rfl
lemma
MulOpposite.unop_mul
Algebra
Mathlib/Algebra/Opposites.lean
[]
[]
https://github.com/leanprover-community/mathlib4
b9f14353520df73472ae3825fb53f86559a01319
op_inv [Inv α] (x : α) : op x⁻¹ = (op x)⁻¹
rfl
lemma
MulOpposite.op_inv
Algebra
Mathlib/Algebra/Opposites.lean
[]
[]
https://github.com/leanprover-community/mathlib4
b9f14353520df73472ae3825fb53f86559a01319
unop_inv [Inv α] (x : αᵐᵒᵖ) : unop x⁻¹ = (unop x)⁻¹
rfl
lemma
MulOpposite.unop_inv
Algebra
Mathlib/Algebra/Opposites.lean
[]
[]
https://github.com/leanprover-community/mathlib4
b9f14353520df73472ae3825fb53f86559a01319
op_sub [Sub α] (x y : α) : op (x - y) = op x - op y
rfl
lemma
MulOpposite.op_sub
Algebra
Mathlib/Algebra/Opposites.lean
[]
[]
https://github.com/leanprover-community/mathlib4
b9f14353520df73472ae3825fb53f86559a01319
unop_sub [Sub α] (x y : αᵐᵒᵖ) : unop (x - y) = unop x - unop y
rfl
lemma
MulOpposite.unop_sub
Algebra
Mathlib/Algebra/Opposites.lean
[]
[]
https://github.com/leanprover-community/mathlib4
b9f14353520df73472ae3825fb53f86559a01319
op_smul [SMul α β] (a : α) (b : β) : op (a • b) = a • op b
rfl
lemma
MulOpposite.op_smul
Algebra
Mathlib/Algebra/Opposites.lean
[]
[]
https://github.com/leanprover-community/mathlib4
b9f14353520df73472ae3825fb53f86559a01319
unop_smul [SMul α β] (a : α) (b : βᵐᵒᵖ) : unop (a • b) = a • unop b
rfl
lemma
MulOpposite.unop_smul
Algebra
Mathlib/Algebra/Opposites.lean
[]
[]
https://github.com/leanprover-community/mathlib4
b9f14353520df73472ae3825fb53f86559a01319
unop_eq_zero_iff [Zero α] (a : αᵐᵒᵖ) : a.unop = (0 : α) ↔ a = (0 : αᵐᵒᵖ)
unop_injective.eq_iff' rfl
theorem
MulOpposite.unop_eq_zero_iff
Algebra
Mathlib/Algebra/Opposites.lean
[]
[]
https://github.com/leanprover-community/mathlib4
b9f14353520df73472ae3825fb53f86559a01319
op_eq_zero_iff [Zero α] (a : α) : op a = (0 : αᵐᵒᵖ) ↔ a = (0 : α)
op_injective.eq_iff' rfl
theorem
MulOpposite.op_eq_zero_iff
Algebra
Mathlib/Algebra/Opposites.lean
[]
[]
https://github.com/leanprover-community/mathlib4
b9f14353520df73472ae3825fb53f86559a01319
unop_ne_zero_iff [Zero α] (a : αᵐᵒᵖ) : a.unop ≠ (0 : α) ↔ a ≠ (0 : αᵐᵒᵖ)
not_congr <| unop_eq_zero_iff a
theorem
MulOpposite.unop_ne_zero_iff
Algebra
Mathlib/Algebra/Opposites.lean
[]
[]
https://github.com/leanprover-community/mathlib4
b9f14353520df73472ae3825fb53f86559a01319
op_ne_zero_iff [Zero α] (a : α) : op a ≠ (0 : αᵐᵒᵖ) ↔ a ≠ (0 : α)
not_congr <| op_eq_zero_iff a
theorem
MulOpposite.op_ne_zero_iff
Algebra
Mathlib/Algebra/Opposites.lean
[]
[]
https://github.com/leanprover-community/mathlib4
b9f14353520df73472ae3825fb53f86559a01319
unop_eq_one_iff [One α] (a : αᵐᵒᵖ) : a.unop = 1 ↔ a = 1
unop_injective.eq_iff' rfl
theorem
MulOpposite.unop_eq_one_iff
Algebra
Mathlib/Algebra/Opposites.lean
[]
[]
https://github.com/leanprover-community/mathlib4
b9f14353520df73472ae3825fb53f86559a01319
op_eq_one_iff [One α] (a : α) : op a = 1 ↔ a = 1
op_injective.eq_iff
lemma
MulOpposite.op_eq_one_iff
Algebra
Mathlib/Algebra/Opposites.lean
[]
[]
https://github.com/leanprover-community/mathlib4
b9f14353520df73472ae3825fb53f86559a01319
instOne [One α] : One αᵃᵒᵖ
where one := op 1
instance
AddOpposite.instOne
Algebra
Mathlib/Algebra/Opposites.lean
[]
[]
https://github.com/leanprover-community/mathlib4
b9f14353520df73472ae3825fb53f86559a01319
unop_one [One α] : unop 1 = (1 : α)
rfl
lemma
AddOpposite.unop_one
Algebra
Mathlib/Algebra/Opposites.lean
[]
[]
https://github.com/leanprover-community/mathlib4
b9f14353520df73472ae3825fb53f86559a01319
op_eq_one_iff [One α] {a : α} : op a = 1 ↔ a = 1
op_injective.eq_iff
lemma
AddOpposite.op_eq_one_iff
Algebra
Mathlib/Algebra/Opposites.lean
[]
[]
https://github.com/leanprover-community/mathlib4
b9f14353520df73472ae3825fb53f86559a01319
unop_eq_one_iff [One α] {a : αᵃᵒᵖ} : unop a = 1 ↔ a = 1
unop_injective.eq_iff
lemma
AddOpposite.unop_eq_one_iff
Algebra
Mathlib/Algebra/Opposites.lean
[]
[]
https://github.com/leanprover-community/mathlib4
b9f14353520df73472ae3825fb53f86559a01319
instMul [Mul α] : Mul αᵃᵒᵖ
where mul a b := op (unop a * unop b)
instance
AddOpposite.instMul
Algebra
Mathlib/Algebra/Opposites.lean
[]
[]
https://github.com/leanprover-community/mathlib4
b9f14353520df73472ae3825fb53f86559a01319
op_mul [Mul α] (a b : α) : op (a * b) = op a * op b
rfl
lemma
AddOpposite.op_mul
Algebra
Mathlib/Algebra/Opposites.lean
[]
[]
https://github.com/leanprover-community/mathlib4
b9f14353520df73472ae3825fb53f86559a01319
unop_mul [Mul α] (a b : αᵃᵒᵖ) : unop (a * b) = unop a * unop b
rfl
lemma
AddOpposite.unop_mul
Algebra
Mathlib/Algebra/Opposites.lean
[]
[]
https://github.com/leanprover-community/mathlib4
b9f14353520df73472ae3825fb53f86559a01319
instInv [Inv α] : Inv αᵃᵒᵖ
where inv a := op (unop a)⁻¹
instance
AddOpposite.instInv
Algebra
Mathlib/Algebra/Opposites.lean
[]
[]
https://github.com/leanprover-community/mathlib4
b9f14353520df73472ae3825fb53f86559a01319
instInvolutiveInv [InvolutiveInv α] : InvolutiveInv αᵃᵒᵖ
where inv_inv _ := unop_injective <| inv_inv _
instance
AddOpposite.instInvolutiveInv
Algebra
Mathlib/Algebra/Opposites.lean
[]
[ "InvolutiveInv", "inv_inv" ]
https://github.com/leanprover-community/mathlib4
b9f14353520df73472ae3825fb53f86559a01319
op_inv [Inv α] (a : α) : op a⁻¹ = (op a)⁻¹
rfl
lemma
AddOpposite.op_inv
Algebra
Mathlib/Algebra/Opposites.lean
[]
[]
https://github.com/leanprover-community/mathlib4
b9f14353520df73472ae3825fb53f86559a01319
unop_inv [Inv α] (a : αᵃᵒᵖ) : unop a⁻¹ = (unop a)⁻¹
rfl
lemma
AddOpposite.unop_inv
Algebra
Mathlib/Algebra/Opposites.lean
[]
[]
https://github.com/leanprover-community/mathlib4
b9f14353520df73472ae3825fb53f86559a01319
instDiv [Div α] : Div αᵃᵒᵖ
where div a b := op (unop a / unop b)
instance
AddOpposite.instDiv
Algebra
Mathlib/Algebra/Opposites.lean
[]
[]
https://github.com/leanprover-community/mathlib4
b9f14353520df73472ae3825fb53f86559a01319
op_div [Div α] (a b : α) : op (a / b) = op a / op b
rfl
lemma
AddOpposite.op_div
Algebra
Mathlib/Algebra/Opposites.lean
[]
[]
https://github.com/leanprover-community/mathlib4
b9f14353520df73472ae3825fb53f86559a01319
unop_div [Div α] (a b : αᵃᵒᵖ) : unop (a / b) = unop a / unop b
rfl
lemma
AddOpposite.unop_div
Algebra
Mathlib/Algebra/Opposites.lean
[]
[]
https://github.com/leanprover-community/mathlib4
b9f14353520df73472ae3825fb53f86559a01319
SemigroupPEmpty : Semigroup PEmpty.{u + 1}
where mul x _ := by cases x mul_assoc x y z := by cases x
instance
SemigroupPEmpty
Algebra
Mathlib/Algebra/PEmptyInstances.lean
[]
[ "Semigroup", "mul_assoc" ]
https://github.com/leanprover-community/mathlib4
b9f14353520df73472ae3825fb53f86559a01319
discrim [Ring R] (a b c : R) : R
b ^ 2 - 4 * a * c
def
discrim
Algebra
Mathlib/Algebra/QuadraticDiscriminant.lean
[]
[ "Ring" ]
Discriminant of a quadratic
https://github.com/leanprover-community/mathlib4
b9f14353520df73472ae3825fb53f86559a01319
discrim_neg [Ring R] (a b c : R) : discrim (-a) (-b) (-c) = discrim a b c
by simp [discrim]
lemma
discrim_neg
Algebra
Mathlib/Algebra/QuadraticDiscriminant.lean
[]
[ "Ring", "discrim" ]
https://github.com/leanprover-community/mathlib4
b9f14353520df73472ae3825fb53f86559a01319
discrim_eq_sq_of_quadratic_eq_zero {x : R} (h : a * (x * x) + b * x + c = 0) : discrim a b c = (2 * a * x + b) ^ 2
by rw [discrim] linear_combination -4 * a * h
lemma
discrim_eq_sq_of_quadratic_eq_zero
Algebra
Mathlib/Algebra/QuadraticDiscriminant.lean
[]
[ "discrim" ]
https://github.com/leanprover-community/mathlib4
b9f14353520df73472ae3825fb53f86559a01319
quadratic_eq_zero_iff_discrim_eq_sq [NeZero (2 : R)] [NoZeroDivisors R] (ha : a ≠ 0) (x : R) : a * (x * x) + b * x + c = 0 ↔ discrim a b c = (2 * a * x + b) ^ 2
by refine ⟨discrim_eq_sq_of_quadratic_eq_zero, fun h ↦ ?_⟩ rw [discrim] at h have ha : 2 * 2 * a ≠ 0 := mul_ne_zero (mul_ne_zero (NeZero.ne _) (NeZero.ne _)) ha apply mul_left_cancel₀ ha linear_combination -h
theorem
quadratic_eq_zero_iff_discrim_eq_sq
Algebra
Mathlib/Algebra/QuadraticDiscriminant.lean
[]
[ "NoZeroDivisors", "discrim", "mul_left_cancel₀", "mul_ne_zero" ]
A quadratic has roots if and only if its discriminant equals some square.
https://github.com/leanprover-community/mathlib4
b9f14353520df73472ae3825fb53f86559a01319
quadratic_ne_zero_of_discrim_ne_sq (h : ∀ s : R, discrim a b c ≠ s ^ 2) (x : R) : a * (x * x) + b * x + c ≠ 0
mt discrim_eq_sq_of_quadratic_eq_zero (h _)
theorem
quadratic_ne_zero_of_discrim_ne_sq
Algebra
Mathlib/Algebra/QuadraticDiscriminant.lean
[]
[ "discrim", "discrim_eq_sq_of_quadratic_eq_zero" ]
A quadratic has no root if its discriminant has no square root.
https://github.com/leanprover-community/mathlib4
b9f14353520df73472ae3825fb53f86559a01319
quadratic_eq_zero_iff (ha : a ≠ 0) {s : K} (h : discrim a b c = s * s) (x : K) : a * (x * x) + b * x + c = 0 ↔ x = (-b + s) / (2 * a) ∨ x = (-b - s) / (2 * a)
by rw [quadratic_eq_zero_iff_discrim_eq_sq ha, h, sq, mul_self_eq_mul_self_iff] field_simp grind
theorem
quadratic_eq_zero_iff
Algebra
Mathlib/Algebra/QuadraticDiscriminant.lean
[]
[ "discrim", "mul_self_eq_mul_self_iff", "quadratic_eq_zero_iff_discrim_eq_sq" ]
Roots of a quadratic equation.
https://github.com/leanprover-community/mathlib4
b9f14353520df73472ae3825fb53f86559a01319
exists_quadratic_eq_zero (ha : a ≠ 0) (h : ∃ s, discrim a b c = s * s) : ∃ x, a * (x * x) + b * x + c = 0
by rcases h with ⟨s, hs⟩ use (-b + s) / (2 * a) rw [quadratic_eq_zero_iff ha hs] simp
theorem
exists_quadratic_eq_zero
Algebra
Mathlib/Algebra/QuadraticDiscriminant.lean
[]
[ "discrim", "quadratic_eq_zero_iff" ]
A quadratic has roots if its discriminant has square roots
https://github.com/leanprover-community/mathlib4
b9f14353520df73472ae3825fb53f86559a01319
quadratic_eq_zero_iff_of_discrim_eq_zero (ha : a ≠ 0) (h : discrim a b c = 0) (x : K) : a * (x * x) + b * x + c = 0 ↔ x = -b / (2 * a)
by have : discrim a b c = 0 * 0 := by rw [h, mul_zero] rw [quadratic_eq_zero_iff ha this, add_zero, sub_zero, or_self_iff]
theorem
quadratic_eq_zero_iff_of_discrim_eq_zero
Algebra
Mathlib/Algebra/QuadraticDiscriminant.lean
[]
[ "discrim", "quadratic_eq_zero_iff" ]
Root of a quadratic when its discriminant equals zero
https://github.com/leanprover-community/mathlib4
b9f14353520df73472ae3825fb53f86559a01319
discrim_eq_zero_of_existsUnique (ha : a ≠ 0) (h : ∃! x, a * (x * x) + b * x + c = 0) : discrim a b c = 0
by simp_rw [quadratic_eq_zero_iff_discrim_eq_sq ha] at h generalize discrim a b c = d at h obtain ⟨x, rfl, hx⟩ := h specialize hx (-(x + b / a)) grind
theorem
discrim_eq_zero_of_existsUnique
Algebra
Mathlib/Algebra/QuadraticDiscriminant.lean
[]
[ "discrim", "quadratic_eq_zero_iff_discrim_eq_sq" ]
https://github.com/leanprover-community/mathlib4
b9f14353520df73472ae3825fb53f86559a01319
discrim_eq_zero_iff (ha : a ≠ 0) : discrim a b c = 0 ↔ (∃! x, a * (x * x) + b * x + c = 0)
by refine ⟨fun hd => ?_, discrim_eq_zero_of_existsUnique ha⟩ simp_rw [quadratic_eq_zero_iff_of_discrim_eq_zero ha hd, existsUnique_eq]
theorem
discrim_eq_zero_iff
Algebra
Mathlib/Algebra/QuadraticDiscriminant.lean
[]
[ "discrim", "discrim_eq_zero_of_existsUnique", "existsUnique_eq", "quadratic_eq_zero_iff_of_discrim_eq_zero" ]
https://github.com/leanprover-community/mathlib4
b9f14353520df73472ae3825fb53f86559a01319
discrim_le_zero (h : ∀ x : K, 0 ≤ a * (x * x) + b * x + c) : discrim a b c ≤ 0
by rw [discrim, sq] obtain ha | rfl | ha : a < 0 ∨ a = 0 ∨ 0 < a := lt_trichotomy a 0 -- if a < 0 · have : Tendsto (fun x => (a * x + b) * x + c) atTop atBot := tendsto_atBot_add_const_right _ c <| (tendsto_atBot_add_const_right _ b (tendsto_id.const_mul_atTop_of_neg ha)).atBot_mul_atTop₀ ...
theorem
discrim_le_zero
Algebra
Mathlib/Algebra/QuadraticDiscriminant.lean
[]
[ "discrim", "eq_or_ne", "lt_trichotomy", "mul_assoc", "mul_div_cancel₀", "zero_le_four" ]
If a polynomial of degree 2 is always nonnegative, then its discriminant is nonpositive
https://github.com/leanprover-community/mathlib4
b9f14353520df73472ae3825fb53f86559a01319
discrim_le_zero_of_nonpos (h : ∀ x : K, a * (x * x) + b * x + c ≤ 0) : discrim a b c ≤ 0
discrim_neg a b c ▸ discrim_le_zero <| by simpa only [neg_mul, ← neg_add, neg_nonneg]
lemma
discrim_le_zero_of_nonpos
Algebra
Mathlib/Algebra/QuadraticDiscriminant.lean
[]
[ "discrim", "discrim_le_zero", "discrim_neg", "neg_mul" ]
https://github.com/leanprover-community/mathlib4
b9f14353520df73472ae3825fb53f86559a01319
discrim_lt_zero (ha : a ≠ 0) (h : ∀ x : K, 0 < a * (x * x) + b * x + c) : discrim a b c < 0
by have : ∀ x : K, 0 ≤ a * (x * x) + b * x + c := fun x => le_of_lt (h x) refine lt_of_le_of_ne (discrim_le_zero this) fun h' ↦ ?_ have := h (-b / (2 * a)) have : a * (-b / (2 * a)) * (-b / (2 * a)) + b * (-b / (2 * a)) + c = 0 := by rw [mul_assoc, quadratic_eq_zero_iff_of_discrim_eq_zero ha h' (-b / (2 * a...
theorem
discrim_lt_zero
Algebra
Mathlib/Algebra/QuadraticDiscriminant.lean
[]
[ "discrim", "discrim_le_zero", "le_of_lt", "lt_of_le_of_ne", "mul_assoc", "quadratic_eq_zero_iff_of_discrim_eq_zero" ]
If a polynomial of degree 2 is always positive, then its discriminant is negative, at least when the coefficient of the quadratic term is nonzero.
https://github.com/leanprover-community/mathlib4
b9f14353520df73472ae3825fb53f86559a01319
discrim_lt_zero_of_neg (ha : a ≠ 0) (h : ∀ x : K, a * (x * x) + b * x + c < 0) : discrim a b c < 0
discrim_neg a b c ▸ discrim_lt_zero (neg_ne_zero.2 ha) <| by simpa only [neg_mul, ← neg_add, neg_pos]
lemma
discrim_lt_zero_of_neg
Algebra
Mathlib/Algebra/QuadraticDiscriminant.lean
[]
[ "discrim", "discrim_lt_zero", "discrim_neg", "neg_mul" ]
https://github.com/leanprover-community/mathlib4
b9f14353520df73472ae3825fb53f86559a01319
Shelf (α : Type u) where /-- The action of the `Shelf` over `α` -/ act : α → α → α /-- A verification that `act` is self-distributive -/ self_distrib : ∀ {x y z : α}, act x (act y z) = act (act x y) (act x z)
class
Shelf
Algebra
Mathlib/Algebra/Quandle.lean
[]
[]
A *Shelf* is a structure with a self-distributive binary operation. The binary operation is regarded as a left action of the type on itself.
https://github.com/leanprover-community/mathlib4
b9f14353520df73472ae3825fb53f86559a01319
UnitalShelf (α : Type u) extends Shelf α, One α where one_act : ∀ a : α, act 1 a = a act_one : ∀ a : α, act a 1 = a
class
UnitalShelf
Algebra
Mathlib/Algebra/Quandle.lean
[]
[ "Shelf" ]
A *unital shelf* is a shelf equipped with an element `1` such that, for all elements `x`, we have both `x ◃ 1` and `1 ◃ x` equal `x`.
https://github.com/leanprover-community/mathlib4
b9f14353520df73472ae3825fb53f86559a01319
ShelfHom (S₁ : Type*) (S₂ : Type*) [Shelf S₁] [Shelf S₂] where /-- The function under the Shelf Homomorphism -/ toFun : S₁ → S₂ /-- The homomorphism property of a Shelf Homomorphism -/ map_act' : ∀ {x y : S₁}, toFun (Shelf.act x y) = Shelf.act (toFun x) (toFun y)
structure
ShelfHom
Algebra
Mathlib/Algebra/Quandle.lean
[]
[ "Shelf" ]
The type of homomorphisms between shelves. This is also the notion of rack and quandle homomorphisms.
https://github.com/leanprover-community/mathlib4
b9f14353520df73472ae3825fb53f86559a01319
Rack (α : Type u) extends Shelf α where /-- The inverse actions of the elements -/ invAct : α → α → α /-- Proof of left inverse -/ left_inv : ∀ x, Function.LeftInverse (invAct x) (act x) /-- Proof of right inverse -/ right_inv : ∀ x, Function.RightInverse (invAct x) (act x) /-- Action of a Shelf -/ scoped[...
class
Rack
Algebra
Mathlib/Algebra/Quandle.lean
[]
[ "Shelf", "ShelfHom" ]
A *rack* is an automorphic set (a set with an action on itself by bijections) that is self-distributive. It is a shelf such that each element's action is invertible. The notations `x ◃ y` and `x ◃⁻¹ y` denote the action and the inverse action, respectively, and they are right associative.
https://github.com/leanprover-community/mathlib4
b9f14353520df73472ae3825fb53f86559a01319
act_act_self_eq (x y : S) : (x ◃ y) ◃ x = x ◃ y
by have h : (x ◃ y) ◃ x = (x ◃ y) ◃ (x ◃ 1) := by rw [act_one] rw [h, ← Shelf.self_distrib, act_one]
lemma
UnitalShelf.act_act_self_eq
Algebra
Mathlib/Algebra/Quandle.lean
[]
[]
A monoid is *graphic* if, for all `x` and `y`, the *graphic identity* `(x * y) * x = x * y` holds. For a unital shelf, this graphic identity holds.
https://github.com/leanprover-community/mathlib4
b9f14353520df73472ae3825fb53f86559a01319
act_idem (x : S) : (x ◃ x) = x
by rw [← act_one x, ← Shelf.self_distrib, act_one]
lemma
UnitalShelf.act_idem
Algebra
Mathlib/Algebra/Quandle.lean
[]
[]
https://github.com/leanprover-community/mathlib4
b9f14353520df73472ae3825fb53f86559a01319
act_self_act_eq (x y : S) : x ◃ (x ◃ y) = x ◃ y
by have h : x ◃ (x ◃ y) = (x ◃ 1) ◃ (x ◃ y) := by rw [act_one] rw [h, ← Shelf.self_distrib, one_act]
lemma
UnitalShelf.act_self_act_eq
Algebra
Mathlib/Algebra/Quandle.lean
[]
[]
https://github.com/leanprover-community/mathlib4
b9f14353520df73472ae3825fb53f86559a01319
assoc (x y z : S) : (x ◃ y) ◃ z = x ◃ y ◃ z
by rw [self_distrib, self_distrib, act_act_self_eq, act_self_act_eq]
lemma
UnitalShelf.assoc
Algebra
Mathlib/Algebra/Quandle.lean
[]
[]
The associativity of a unital shelf comes for free.
https://github.com/leanprover-community/mathlib4
b9f14353520df73472ae3825fb53f86559a01319
act' (x : R) : R ≃ R
where toFun := Shelf.act x invFun := invAct x left_inv := left_inv x right_inv := right_inv x
def
Rack.act'
Algebra
Mathlib/Algebra/Quandle.lean
[]
[]
A rack acts on itself by equivalences.
https://github.com/leanprover-community/mathlib4
b9f14353520df73472ae3825fb53f86559a01319
act'_apply (x y : R) : act' x y = x ◃ y
rfl
theorem
Rack.act'_apply
Algebra
Mathlib/Algebra/Quandle.lean
[]
[]
https://github.com/leanprover-community/mathlib4
b9f14353520df73472ae3825fb53f86559a01319
act'_symm_apply (x y : R) : (act' x).symm y = x ◃⁻¹ y
rfl
theorem
Rack.act'_symm_apply
Algebra
Mathlib/Algebra/Quandle.lean
[]
[ "symm" ]
https://github.com/leanprover-community/mathlib4
b9f14353520df73472ae3825fb53f86559a01319
invAct_apply (x y : R) : (act' x)⁻¹ y = x ◃⁻¹ y
rfl
theorem
Rack.invAct_apply
Algebra
Mathlib/Algebra/Quandle.lean
[]
[]
https://github.com/leanprover-community/mathlib4
b9f14353520df73472ae3825fb53f86559a01319
invAct_act_eq (x y : R) : x ◃⁻¹ x ◃ y = y
left_inv x y
theorem
Rack.invAct_act_eq
Algebra
Mathlib/Algebra/Quandle.lean
[]
[]
https://github.com/leanprover-community/mathlib4
b9f14353520df73472ae3825fb53f86559a01319
act_invAct_eq (x y : R) : x ◃ x ◃⁻¹ y = y
right_inv x y
theorem
Rack.act_invAct_eq
Algebra
Mathlib/Algebra/Quandle.lean
[]
[]
https://github.com/leanprover-community/mathlib4
b9f14353520df73472ae3825fb53f86559a01319
left_cancel (x : R) {y y' : R} : x ◃ y = x ◃ y' ↔ y = y'
by constructor · apply (act' x).injective rintro rfl rfl
theorem
Rack.left_cancel
Algebra
Mathlib/Algebra/Quandle.lean
[]
[]
https://github.com/leanprover-community/mathlib4
b9f14353520df73472ae3825fb53f86559a01319
left_cancel_inv (x : R) {y y' : R} : x ◃⁻¹ y = x ◃⁻¹ y' ↔ y = y'
by constructor · apply (act' x).symm.injective rintro rfl rfl
theorem
Rack.left_cancel_inv
Algebra
Mathlib/Algebra/Quandle.lean
[]
[]
https://github.com/leanprover-community/mathlib4
b9f14353520df73472ae3825fb53f86559a01319
self_distrib_inv {x y z : R} : x ◃⁻¹ y ◃⁻¹ z = (x ◃⁻¹ y) ◃⁻¹ x ◃⁻¹ z
by rw [← left_cancel (x ◃⁻¹ y), right_inv, ← left_cancel x, right_inv, self_distrib] repeat' rw [right_inv]
theorem
Rack.self_distrib_inv
Algebra
Mathlib/Algebra/Quandle.lean
[]
[]
https://github.com/leanprover-community/mathlib4
b9f14353520df73472ae3825fb53f86559a01319
ad_conj {R : Type*} [Rack R] (x y : R) : act' (x ◃ y) = act' x * act' y * (act' x)⁻¹
by rw [eq_mul_inv_iff_mul_eq]; ext z apply self_distrib.symm
theorem
Rack.ad_conj
Algebra
Mathlib/Algebra/Quandle.lean
[]
[ "Rack", "eq_mul_inv_iff_mul_eq" ]
The *adjoint action* of a rack on itself is `op'`, and the adjoint action of `x ◃ y` is the conjugate of the action of `y` by the action of `x`. It is another way to understand the self-distributivity axiom. This is used in the natural rack homomorphism `toConj` from `R` to `Conj (R ≃ R)` defined by `op'`.
https://github.com/leanprover-community/mathlib4
b9f14353520df73472ae3825fb53f86559a01319
oppositeRack : Rack Rᵐᵒᵖ
where act x y := op (invAct (unop x) (unop y)) self_distrib := by intro x y z induction x induction y induction z simp only [op_inj, unop_op] rw [self_distrib_inv] invAct x y := op (Shelf.act (unop x) (unop y)) left_inv := MulOpposite.rec' fun x => MulOpposite.rec' fun y => by simp rig...
instance
Rack.oppositeRack
Algebra
Mathlib/Algebra/Quandle.lean
[]
[ "MulOpposite.rec'", "Rack" ]
The opposite rack, swapping the roles of `◃` and `◃⁻¹`.
https://github.com/leanprover-community/mathlib4
b9f14353520df73472ae3825fb53f86559a01319
op_act_op_eq {x y : R} : op x ◃ op y = op (x ◃⁻¹ y)
rfl
theorem
Rack.op_act_op_eq
Algebra
Mathlib/Algebra/Quandle.lean
[]
[]
https://github.com/leanprover-community/mathlib4
b9f14353520df73472ae3825fb53f86559a01319
op_invAct_op_eq {x y : R} : op x ◃⁻¹ op y = op (x ◃ y)
rfl
theorem
Rack.op_invAct_op_eq
Algebra
Mathlib/Algebra/Quandle.lean
[]
[]
https://github.com/leanprover-community/mathlib4
b9f14353520df73472ae3825fb53f86559a01319
self_act_act_eq {x y : R} : (x ◃ x) ◃ y = x ◃ y
by rw [← right_inv x y, ← self_distrib]
theorem
Rack.self_act_act_eq
Algebra
Mathlib/Algebra/Quandle.lean
[]
[]
https://github.com/leanprover-community/mathlib4
b9f14353520df73472ae3825fb53f86559a01319
self_invAct_invAct_eq {x y : R} : (x ◃⁻¹ x) ◃⁻¹ y = x ◃⁻¹ y
by have h := @self_act_act_eq _ _ (op x) (op y) simpa using h
theorem
Rack.self_invAct_invAct_eq
Algebra
Mathlib/Algebra/Quandle.lean
[]
[]
https://github.com/leanprover-community/mathlib4
b9f14353520df73472ae3825fb53f86559a01319
self_act_invAct_eq {x y : R} : (x ◃ x) ◃⁻¹ y = x ◃⁻¹ y
by rw [← left_cancel (x ◃ x)] rw [right_inv] rw [self_act_act_eq] rw [right_inv]
theorem
Rack.self_act_invAct_eq
Algebra
Mathlib/Algebra/Quandle.lean
[]
[]
https://github.com/leanprover-community/mathlib4
b9f14353520df73472ae3825fb53f86559a01319
self_invAct_act_eq {x y : R} : (x ◃⁻¹ x) ◃ y = x ◃ y
by have h := @self_act_invAct_eq _ _ (op x) (op y) simpa using h
theorem
Rack.self_invAct_act_eq
Algebra
Mathlib/Algebra/Quandle.lean
[]
[]
https://github.com/leanprover-community/mathlib4
b9f14353520df73472ae3825fb53f86559a01319
self_act_eq_iff_eq {x y : R} : x ◃ x = y ◃ y ↔ x = y
by constructor; swap · rintro rfl; rfl intro h trans (x ◃ x) ◃⁻¹ x ◃ x · rw [← left_cancel (x ◃ x), right_inv, self_act_act_eq] · rw [h, ← left_cancel (y ◃ y), right_inv, self_act_act_eq]
theorem
Rack.self_act_eq_iff_eq
Algebra
Mathlib/Algebra/Quandle.lean
[]
[ "trans" ]
https://github.com/leanprover-community/mathlib4
b9f14353520df73472ae3825fb53f86559a01319
self_invAct_eq_iff_eq {x y : R} : x ◃⁻¹ x = y ◃⁻¹ y ↔ x = y
by have h := @self_act_eq_iff_eq _ _ (op x) (op y) simpa using h
theorem
Rack.self_invAct_eq_iff_eq
Algebra
Mathlib/Algebra/Quandle.lean
[]
[]
https://github.com/leanprover-community/mathlib4
b9f14353520df73472ae3825fb53f86559a01319
selfApplyEquiv (R : Type*) [Rack R] : R ≃ R
where toFun x := x ◃ x invFun x := x ◃⁻¹ x left_inv x := by simp right_inv x := by simp
def
Rack.selfApplyEquiv
Algebra
Mathlib/Algebra/Quandle.lean
[]
[ "Rack" ]
The map `x ↦ x ◃ x` is a bijection. (This has applications for the regular isotopy version of the Reidemeister I move for knot diagrams.)
https://github.com/leanprover-community/mathlib4
b9f14353520df73472ae3825fb53f86559a01319
IsInvolutory (R : Type*) [Rack R] : Prop
∀ x : R, Function.Involutive (Shelf.act x)
def
Rack.IsInvolutory
Algebra
Mathlib/Algebra/Quandle.lean
[]
[ "Function.Involutive", "Rack" ]
An involutory rack is one for which `Rack.oppositeRack R x` is an involution for every x.
https://github.com/leanprover-community/mathlib4
b9f14353520df73472ae3825fb53f86559a01319
involutory_invAct_eq_act {R : Type*} [Rack R] (h : IsInvolutory R) (x y : R) : x ◃⁻¹ y = x ◃ y
by rw [← left_cancel x, right_inv, h x]
theorem
Rack.involutory_invAct_eq_act
Algebra
Mathlib/Algebra/Quandle.lean
[]
[ "Rack" ]
https://github.com/leanprover-community/mathlib4
b9f14353520df73472ae3825fb53f86559a01319
IsAbelian (R : Type*) [Rack R] : Prop
∀ x y z w : R, (x ◃ y) ◃ z ◃ w = (x ◃ z) ◃ y ◃ w
def
Rack.IsAbelian
Algebra
Mathlib/Algebra/Quandle.lean
[]
[ "Rack" ]
An abelian rack is one for which the mediality axiom holds.
https://github.com/leanprover-community/mathlib4
b9f14353520df73472ae3825fb53f86559a01319
assoc_iff_id {R : Type*} [Rack R] {x y z : R} : x ◃ y ◃ z = (x ◃ y) ◃ z ↔ x ◃ z = z
by rw [self_distrib] rw [left_cancel]
theorem
Rack.assoc_iff_id
Algebra
Mathlib/Algebra/Quandle.lean
[]
[ "Rack" ]
Associative racks are uninteresting.
https://github.com/leanprover-community/mathlib4
b9f14353520df73472ae3825fb53f86559a01319
toFun_eq_coe (f : S₁ →◃ S₂) : f.toFun = f
rfl
theorem
ShelfHom.toFun_eq_coe
Algebra
Mathlib/Algebra/Quandle.lean
[]
[]
https://github.com/leanprover-community/mathlib4
b9f14353520df73472ae3825fb53f86559a01319
map_act (f : S₁ →◃ S₂) {x y : S₁} : f (x ◃ y) = f x ◃ f y
map_act' f
theorem
ShelfHom.map_act
Algebra
Mathlib/Algebra/Quandle.lean
[]
[]
https://github.com/leanprover-community/mathlib4
b9f14353520df73472ae3825fb53f86559a01319
id (S : Type*) [Shelf S] : S →◃ S
where toFun := fun x => x map_act' := by simp
def
ShelfHom.id
Algebra
Mathlib/Algebra/Quandle.lean
[]
[ "Shelf" ]
The identity homomorphism
https://github.com/leanprover-community/mathlib4
b9f14353520df73472ae3825fb53f86559a01319
inhabited (S : Type*) [Shelf S] : Inhabited (S →◃ S)
⟨id S⟩
instance
ShelfHom.inhabited
Algebra
Mathlib/Algebra/Quandle.lean
[]
[ "Shelf" ]
https://github.com/leanprover-community/mathlib4
b9f14353520df73472ae3825fb53f86559a01319
comp (g : S₂ →◃ S₃) (f : S₁ →◃ S₂) : S₁ →◃ S₃
where toFun := g.toFun ∘ f.toFun map_act' := by simp
def
ShelfHom.comp
Algebra
Mathlib/Algebra/Quandle.lean
[]
[]
The composition of shelf homomorphisms
https://github.com/leanprover-community/mathlib4
b9f14353520df73472ae3825fb53f86559a01319
comp_apply (g : S₂ →◃ S₃) (f : S₁ →◃ S₂) (x : S₁) : (g.comp f) x = g (f x)
rfl
theorem
ShelfHom.comp_apply
Algebra
Mathlib/Algebra/Quandle.lean
[]
[]
https://github.com/leanprover-community/mathlib4
b9f14353520df73472ae3825fb53f86559a01319
Quandle (α : Type*) extends Rack α where /-- The fixing property of a Quandle -/ fix : ∀ {x : α}, act x x = x
class
Quandle
Algebra
Mathlib/Algebra/Quandle.lean
[]
[ "Rack" ]
A quandle is a rack such that each automorphism fixes its corresponding element.
https://github.com/leanprover-community/mathlib4
b9f14353520df73472ae3825fb53f86559a01319
fix_inv {x : Q} : x ◃⁻¹ x = x
by rw [← left_cancel x] simp
theorem
Quandle.fix_inv
Algebra
Mathlib/Algebra/Quandle.lean
[]
[]
https://github.com/leanprover-community/mathlib4
b9f14353520df73472ae3825fb53f86559a01319
oppositeQuandle : Quandle Qᵐᵒᵖ
where fix := by intro x induction x simp
instance
Quandle.oppositeQuandle
Algebra
Mathlib/Algebra/Quandle.lean
[]
[ "Quandle" ]
https://github.com/leanprover-community/mathlib4
b9f14353520df73472ae3825fb53f86559a01319
Conj (G : Type*)
G
abbrev
Quandle.Conj
Algebra
Mathlib/Algebra/Quandle.lean
[]
[]
The conjugation quandle of a group. Each element of the group acts by the corresponding inner automorphism.
https://github.com/leanprover-community/mathlib4
b9f14353520df73472ae3825fb53f86559a01319
Conj.quandle (G : Type*) [Group G] : Quandle (Conj G)
where act x := @MulAut.conj G _ x self_distrib := by intro x y z dsimp only [MulAut.conj_apply] simp [mul_assoc] invAct x := (@MulAut.conj G _ x).symm left_inv x y := by simp [mul_assoc] right_inv x y := by simp [mul_assoc] fix := by simp
instance
Quandle.Conj.quandle
Algebra
Mathlib/Algebra/Quandle.lean
[]
[ "Group", "MulAut.conj", "MulAut.conj_apply", "Quandle", "mul_assoc", "symm" ]
https://github.com/leanprover-community/mathlib4
b9f14353520df73472ae3825fb53f86559a01319
conj_act_eq_conj {G : Type*} [Group G] (x y : Conj G) : x ◃ y = ((x : G) * (y : G) * (x : G)⁻¹ : G)
rfl
theorem
Quandle.conj_act_eq_conj
Algebra
Mathlib/Algebra/Quandle.lean
[]
[ "Group" ]
https://github.com/leanprover-community/mathlib4
b9f14353520df73472ae3825fb53f86559a01319
conj_swap {G : Type*} [Group G] (x y : Conj G) : x ◃ y = y ↔ y ◃ x = x
by grind [eq_mul_inv_iff_mul_eq]
theorem
Quandle.conj_swap
Algebra
Mathlib/Algebra/Quandle.lean
[]
[ "Group", "eq_mul_inv_iff_mul_eq" ]
https://github.com/leanprover-community/mathlib4
b9f14353520df73472ae3825fb53f86559a01319
Conj.map {G : Type*} {H : Type*} [Group G] [Group H] (f : G →* H) : Conj G →◃ Conj H
where toFun := f map_act' := by simp
def
Quandle.Conj.map
Algebra
Mathlib/Algebra/Quandle.lean
[]
[ "Group" ]
`Conj` is functorial
https://github.com/leanprover-community/mathlib4
b9f14353520df73472ae3825fb53f86559a01319
Dihedral (n : ℕ)
ZMod n
def
Quandle.Dihedral
Algebra
Mathlib/Algebra/Quandle.lean
[]
[ "ZMod" ]
The dihedral quandle. This is the conjugation quandle of the dihedral group restricted to flips. Used for Fox n-colorings of knots.
https://github.com/leanprover-community/mathlib4
b9f14353520df73472ae3825fb53f86559a01319
dihedralAct (n : ℕ) (a : ZMod n) : ZMod n → ZMod n
fun b => 2 * a - b
def
Quandle.dihedralAct
Algebra
Mathlib/Algebra/Quandle.lean
[]
[ "ZMod" ]
The operation for the dihedral quandle. It does not need to be an equivalence because it is an involution (see `dihedralAct.inv`).
https://github.com/leanprover-community/mathlib4
b9f14353520df73472ae3825fb53f86559a01319
dihedralAct.inv (n : ℕ) (a : ZMod n) : Function.Involutive (dihedralAct n a)
by intro b dsimp only [dihedralAct] simp
theorem
Quandle.dihedralAct.inv
Algebra
Mathlib/Algebra/Quandle.lean
[]
[ "Function.Involutive", "ZMod" ]
https://github.com/leanprover-community/mathlib4
b9f14353520df73472ae3825fb53f86559a01319
toConj (R : Type*) [Rack R] : R →◃ Quandle.Conj (R ≃ R)
where toFun := act' map_act' := by intro x y exact ad_conj x y
def
Rack.toConj
Algebra
Mathlib/Algebra/Quandle.lean
[]
[ "Quandle.Conj", "Rack" ]
This is the natural rack homomorphism to the conjugation quandle of the group `R ≃ R` that acts on the rack.
https://github.com/leanprover-community/mathlib4
b9f14353520df73472ae3825fb53f86559a01319
PreEnvelGroup (R : Type u) : Type u | unit : PreEnvelGroup R | incl (x : R) : PreEnvelGroup R | mul (a b : PreEnvelGroup R) : PreEnvelGroup R | inv (a : PreEnvelGroup R) : PreEnvelGroup R
inductive
Rack.PreEnvelGroup
Algebra
Mathlib/Algebra/Quandle.lean
[]
[]
Free generators of the enveloping group.
https://github.com/leanprover-community/mathlib4
b9f14353520df73472ae3825fb53f86559a01319
PreEnvelGroup.inhabited (R : Type u) : Inhabited (PreEnvelGroup R)
⟨PreEnvelGroup.unit⟩
instance
Rack.PreEnvelGroup.inhabited
Algebra
Mathlib/Algebra/Quandle.lean
[]
[]
https://github.com/leanprover-community/mathlib4
b9f14353520df73472ae3825fb53f86559a01319
PreEnvelGroupRel' (R : Type u) [Rack R] : PreEnvelGroup R → PreEnvelGroup R → Type u | refl {a : PreEnvelGroup R} : PreEnvelGroupRel' R a a | symm {a b : PreEnvelGroup R} (hab : PreEnvelGroupRel' R a b) : PreEnvelGroupRel' R b a | trans {a b c : PreEnvelGroup R} (hab : PreEnvelGroupRel' R a b) (hbc : PreEnvel...
inductive
Rack.PreEnvelGroupRel'
Algebra
Mathlib/Algebra/Quandle.lean
[]
[ "Rack", "inv_mul_cancel", "mul_one", "one_mul", "refl", "symm", "trans" ]
Relations for the enveloping group. This is a type-valued relation because `toEnvelGroup.mapAux.well_def` inducts on it to show `toEnvelGroup.map` is well-defined. The relation `PreEnvelGroupRel` is the `Prop`-valued version, which is used to define `EnvelGroup` itself.
https://github.com/leanprover-community/mathlib4
b9f14353520df73472ae3825fb53f86559a01319
PreEnvelGroupRel'.inhabited (R : Type u) [Rack R] : Inhabited (PreEnvelGroupRel' R unit unit)
⟨PreEnvelGroupRel'.refl⟩
instance
Rack.PreEnvelGroupRel'.inhabited
Algebra
Mathlib/Algebra/Quandle.lean
[]
[ "Rack" ]
https://github.com/leanprover-community/mathlib4
b9f14353520df73472ae3825fb53f86559a01319
PreEnvelGroupRel (R : Type u) [Rack R] : PreEnvelGroup R → PreEnvelGroup R → Prop | rel {a b : PreEnvelGroup R} (r : PreEnvelGroupRel' R a b) : PreEnvelGroupRel R a b
inductive
Rack.PreEnvelGroupRel
Algebra
Mathlib/Algebra/Quandle.lean
[]
[ "Rack" ]
The `PreEnvelGroupRel` relation as a `Prop`. Used as the relation for `PreEnvelGroup.setoid`.
https://github.com/leanprover-community/mathlib4
b9f14353520df73472ae3825fb53f86559a01319
PreEnvelGroupRel'.rel {R : Type u} [Rack R] {a b : PreEnvelGroup R} : PreEnvelGroupRel' R a b → PreEnvelGroupRel R a b
PreEnvelGroupRel.rel
theorem
Rack.PreEnvelGroupRel'.rel
Algebra
Mathlib/Algebra/Quandle.lean
[]
[ "Rack" ]
A quick way to convert a `PreEnvelGroupRel'` to a `PreEnvelGroupRel`.
https://github.com/leanprover-community/mathlib4
b9f14353520df73472ae3825fb53f86559a01319
PreEnvelGroupRel.refl {R : Type u} [Rack R] {a : PreEnvelGroup R} : PreEnvelGroupRel R a a
PreEnvelGroupRel.rel PreEnvelGroupRel'.refl
theorem
Rack.PreEnvelGroupRel.refl
Algebra
Mathlib/Algebra/Quandle.lean
[]
[ "Rack" ]
https://github.com/leanprover-community/mathlib4
b9f14353520df73472ae3825fb53f86559a01319
PreEnvelGroupRel.symm {R : Type u} [Rack R] {a b : PreEnvelGroup R} : PreEnvelGroupRel R a b → PreEnvelGroupRel R b a
| ⟨r⟩ => r.symm.rel
theorem
Rack.PreEnvelGroupRel.symm
Algebra
Mathlib/Algebra/Quandle.lean
[]
[ "Rack" ]
https://github.com/leanprover-community/mathlib4
b9f14353520df73472ae3825fb53f86559a01319