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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
begin rw [discrim], linear_combination -4 * a * h end
lemma
discrim_eq_sq_of_quadratic_eq_zero
algebra
src/algebra/quadratic_discriminant.lean
[ "algebra.char_p.invertible", "order.filter.at_top_bot", "tactic.linarith", "tactic.field_simp", "tactic.linear_combination" ]
[ "discrim" ]
https://github.com/leanprover-community/mathlib
65a1391a0106c9204fe45bc73a039f056558cb83
quadratic_eq_zero_iff_discrim_eq_sq [ne_zero (2 : R)] [no_zero_divisors R] (ha : a ≠ 0) {x : R} : a * x * x + b * x + c = 0 ↔ discrim a b c = (2 * a * x + b) ^ 2
begin refine ⟨discrim_eq_sq_of_quadratic_eq_zero, λ h, _⟩, rw [discrim] at h, have ha : 2 * 2 * a ≠ 0 := mul_ne_zero (mul_ne_zero (ne_zero.ne _) (ne_zero.ne _)) ha, apply mul_left_cancel₀ ha, linear_combination -h end
lemma
quadratic_eq_zero_iff_discrim_eq_sq
algebra
src/algebra/quadratic_discriminant.lean
[ "algebra.char_p.invertible", "order.filter.at_top_bot", "tactic.linarith", "tactic.field_simp", "tactic.linear_combination" ]
[ "discrim", "mul_left_cancel₀", "mul_ne_zero", "ne_zero", "ne_zero.ne", "no_zero_divisors" ]
A quadratic has roots if and only if its discriminant equals some square.
https://github.com/leanprover-community/mathlib
65a1391a0106c9204fe45bc73a039f056558cb83
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 _
lemma
quadratic_ne_zero_of_discrim_ne_sq
algebra
src/algebra/quadratic_discriminant.lean
[ "algebra.char_p.invertible", "order.filter.at_top_bot", "tactic.linarith", "tactic.field_simp", "tactic.linear_combination" ]
[ "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/mathlib
65a1391a0106c9204fe45bc73a039f056558cb83
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)
begin rw [quadratic_eq_zero_iff_discrim_eq_sq ha, h, sq, mul_self_eq_mul_self_iff], field_simp, apply or_congr, { split; intro h'; linear_combination -h' }, { split; intro h'; linear_combination h' }, end
lemma
quadratic_eq_zero_iff
algebra
src/algebra/quadratic_discriminant.lean
[ "algebra.char_p.invertible", "order.filter.at_top_bot", "tactic.linarith", "tactic.field_simp", "tactic.linear_combination" ]
[ "discrim", "mul_self_eq_mul_self_iff", "quadratic_eq_zero_iff_discrim_eq_sq" ]
Roots of a quadratic equation.
https://github.com/leanprover-community/mathlib
65a1391a0106c9204fe45bc73a039f056558cb83
exists_quadratic_eq_zero (ha : a ≠ 0) (h : ∃ s, discrim a b c = s * s) : ∃ x, a * x * x + b * x + c = 0
begin rcases h with ⟨s, hs⟩, use (-b + s) / (2 * a), rw quadratic_eq_zero_iff ha hs, simp end
lemma
exists_quadratic_eq_zero
algebra
src/algebra/quadratic_discriminant.lean
[ "algebra.char_p.invertible", "order.filter.at_top_bot", "tactic.linarith", "tactic.field_simp", "tactic.linear_combination" ]
[ "discrim", "quadratic_eq_zero_iff" ]
A quadratic has roots if its discriminant has square roots
https://github.com/leanprover-community/mathlib
65a1391a0106c9204fe45bc73a039f056558cb83
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)
begin 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] end
lemma
quadratic_eq_zero_iff_of_discrim_eq_zero
algebra
src/algebra/quadratic_discriminant.lean
[ "algebra.char_p.invertible", "order.filter.at_top_bot", "tactic.linarith", "tactic.field_simp", "tactic.linear_combination" ]
[ "discrim", "mul_zero", "quadratic_eq_zero_iff" ]
Root of a quadratic when its discriminant equals zero
https://github.com/leanprover-community/mathlib
65a1391a0106c9204fe45bc73a039f056558cb83
discrim_le_zero (h : ∀ x : K, 0 ≤ a * x * x + b * x + c) : discrim a b c ≤ 0
begin rw [discrim, sq], obtain ha|rfl|ha : a < 0 ∨ a = 0 ∨ 0 < a := lt_trichotomy a 0, -- if a < 0 { have : tendsto (λ x, (a * x + b) * x + c) at_top at_bot := tendsto_at_bot_add_const_right _ c ((tendsto_at_bot_add_const_right _ b (tendsto_id.neg_const_mul_at_top ha)).at_bot_mul_at_top tendsto_id),...
lemma
discrim_le_zero
algebra
src/algebra/quadratic_discriminant.lean
[ "algebra.char_p.invertible", "order.filter.at_top_bot", "tactic.linarith", "tactic.field_simp", "tactic.linear_combination" ]
[ "discrim", "eq_or_ne", "mul_div_cancel'", "ring", "zero_le_four" ]
If a polynomial of degree 2 is always nonnegative, then its discriminant is nonpositive.
https://github.com/leanprover-community/mathlib
65a1391a0106c9204fe45bc73a039f056558cb83
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
src/algebra/quadratic_discriminant.lean
[ "algebra.char_p.invertible", "order.filter.at_top_bot", "tactic.linarith", "tactic.field_simp", "tactic.linear_combination" ]
[ "discrim", "discrim_le_zero", "discrim_neg", "neg_mul" ]
https://github.com/leanprover-community/mathlib
65a1391a0106c9204fe45bc73a039f056558cb83
discrim_lt_zero (ha : a ≠ 0) (h : ∀ x : K, 0 < a * x * x + b * x + c) : discrim a b c < 0
begin have : ∀ x : K, 0 ≤ a*x*x + b*x + c := assume x, le_of_lt (h x), refine lt_of_le_of_ne (discrim_le_zero this) _, assume h', have := h (-b / (2 * a)), have : a * (-b / (2 * a)) * (-b / (2 * a)) + b * (-b / (2 * a)) + c = 0, { rw [quadratic_eq_zero_iff_of_discrim_eq_zero ha h' (-b / (2 * a))] }, linar...
lemma
discrim_lt_zero
algebra
src/algebra/quadratic_discriminant.lean
[ "algebra.char_p.invertible", "order.filter.at_top_bot", "tactic.linarith", "tactic.field_simp", "tactic.linear_combination" ]
[ "discrim", "discrim_le_zero", "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/mathlib
65a1391a0106c9204fe45bc73a039f056558cb83
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
src/algebra/quadratic_discriminant.lean
[ "algebra.char_p.invertible", "order.filter.at_top_bot", "tactic.linarith", "tactic.field_simp", "tactic.linear_combination" ]
[ "discrim", "discrim_lt_zero", "discrim_neg", "neg_mul" ]
https://github.com/leanprover-community/mathlib
65a1391a0106c9204fe45bc73a039f056558cb83
shelf (α : Type u)
(act : α → α → α) (self_distrib : ∀ {x y z : α}, act x (act y z) = act (act x y) (act x z))
class
shelf
algebra
src/algebra/quandle.lean
[ "algebra.hom.equiv.basic", "algebra.hom.aut", "data.zmod.defs", "tactic.group" ]
[]
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/mathlib
65a1391a0106c9204fe45bc73a039f056558cb83
unital_shelf (α : Type u) extends shelf α, has_one α
(one_act : ∀ a : α, act 1 a = a) (act_one : ∀ a : α, act a 1 = a)
class
unital_shelf
algebra
src/algebra/quandle.lean
[ "algebra.hom.equiv.basic", "algebra.hom.aut", "data.zmod.defs", "tactic.group" ]
[ "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/mathlib
65a1391a0106c9204fe45bc73a039f056558cb83
shelf_hom (S₁ : Type*) (S₂ : Type*) [shelf S₁] [shelf S₂]
(to_fun : S₁ → S₂) (map_act' : ∀ {x y : S₁}, to_fun (shelf.act x y) = shelf.act (to_fun x) (to_fun y))
structure
shelf_hom
algebra
src/algebra/quandle.lean
[ "algebra.hom.equiv.basic", "algebra.hom.aut", "data.zmod.defs", "tactic.group" ]
[ "shelf" ]
The type of homomorphisms between shelves. This is also the notion of rack and quandle homomorphisms.
https://github.com/leanprover-community/mathlib
65a1391a0106c9204fe45bc73a039f056558cb83
rack (α : Type u) extends shelf α
(inv_act : α → α → α) (left_inv : ∀ x, function.left_inverse (inv_act x) (act x)) (right_inv : ∀ x, function.right_inverse (inv_act x) (act x))
class
rack
algebra
src/algebra/quandle.lean
[ "algebra.hom.equiv.basic", "algebra.hom.aut", "data.zmod.defs", "tactic.group" ]
[ "shelf" ]
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/mathlib
65a1391a0106c9204fe45bc73a039f056558cb83
act_act_self_eq (x y : S) : (x ◃ y) ◃ x = x ◃ y
begin have h : (x ◃ y) ◃ x = (x ◃ y) ◃ (x ◃ 1) := by rw act_one, rw [h, ←shelf.self_distrib, act_one], end
lemma
unital_shelf.act_act_self_eq
algebra
src/algebra/quandle.lean
[ "algebra.hom.equiv.basic", "algebra.hom.aut", "data.zmod.defs", "tactic.group" ]
[]
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/mathlib
65a1391a0106c9204fe45bc73a039f056558cb83
act_idem (x : S) : (x ◃ x) = x
by rw [←act_one x, ←shelf.self_distrib, act_one, act_one]
lemma
unital_shelf.act_idem
algebra
src/algebra/quandle.lean
[ "algebra.hom.equiv.basic", "algebra.hom.aut", "data.zmod.defs", "tactic.group" ]
[]
https://github.com/leanprover-community/mathlib
65a1391a0106c9204fe45bc73a039f056558cb83
act_self_act_eq (x y : S) : x ◃ (x ◃ y) = x ◃ y
begin have h : x ◃ (x ◃ y) = (x ◃ 1) ◃ (x ◃ y) := by rw act_one, rw [h, ←shelf.self_distrib, one_act], end
lemma
unital_shelf.act_self_act_eq
algebra
src/algebra/quandle.lean
[ "algebra.hom.equiv.basic", "algebra.hom.aut", "data.zmod.defs", "tactic.group" ]
[]
https://github.com/leanprover-community/mathlib
65a1391a0106c9204fe45bc73a039f056558cb83
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
unital_shelf.assoc
algebra
src/algebra/quandle.lean
[ "algebra.hom.equiv.basic", "algebra.hom.aut", "data.zmod.defs", "tactic.group" ]
[]
The associativity of a unital shelf comes for free.
https://github.com/leanprover-community/mathlib
65a1391a0106c9204fe45bc73a039f056558cb83
self_distrib {x y z : R} : x ◃ (y ◃ z) = (x ◃ y) ◃ (x ◃ z)
shelf.self_distrib
lemma
rack.self_distrib
algebra
src/algebra/quandle.lean
[ "algebra.hom.equiv.basic", "algebra.hom.aut", "data.zmod.defs", "tactic.group" ]
[]
https://github.com/leanprover-community/mathlib
65a1391a0106c9204fe45bc73a039f056558cb83
act (x : R) : R ≃ R
{ to_fun := shelf.act x, inv_fun := inv_act x, left_inv := left_inv x, right_inv := right_inv x }
def
rack.act
algebra
src/algebra/quandle.lean
[ "algebra.hom.equiv.basic", "algebra.hom.aut", "data.zmod.defs", "tactic.group" ]
[ "inv_fun" ]
A rack acts on itself by equivalences.
https://github.com/leanprover-community/mathlib
65a1391a0106c9204fe45bc73a039f056558cb83
act_apply (x y : R) : act x y = x ◃ y
rfl
lemma
rack.act_apply
algebra
src/algebra/quandle.lean
[ "algebra.hom.equiv.basic", "algebra.hom.aut", "data.zmod.defs", "tactic.group" ]
[]
https://github.com/leanprover-community/mathlib
65a1391a0106c9204fe45bc73a039f056558cb83
act_symm_apply (x y : R) : (act x).symm y = x ◃⁻¹ y
rfl
lemma
rack.act_symm_apply
algebra
src/algebra/quandle.lean
[ "algebra.hom.equiv.basic", "algebra.hom.aut", "data.zmod.defs", "tactic.group" ]
[]
https://github.com/leanprover-community/mathlib
65a1391a0106c9204fe45bc73a039f056558cb83
inv_act_apply (x y : R) : (act x)⁻¹ y = x ◃⁻¹ y
rfl
lemma
rack.inv_act_apply
algebra
src/algebra/quandle.lean
[ "algebra.hom.equiv.basic", "algebra.hom.aut", "data.zmod.defs", "tactic.group" ]
[]
https://github.com/leanprover-community/mathlib
65a1391a0106c9204fe45bc73a039f056558cb83
inv_act_act_eq (x y : R) : x ◃⁻¹ x ◃ y = y
left_inv x y
lemma
rack.inv_act_act_eq
algebra
src/algebra/quandle.lean
[ "algebra.hom.equiv.basic", "algebra.hom.aut", "data.zmod.defs", "tactic.group" ]
[]
https://github.com/leanprover-community/mathlib
65a1391a0106c9204fe45bc73a039f056558cb83
act_inv_act_eq (x y : R) : x ◃ x ◃⁻¹ y = y
right_inv x y
lemma
rack.act_inv_act_eq
algebra
src/algebra/quandle.lean
[ "algebra.hom.equiv.basic", "algebra.hom.aut", "data.zmod.defs", "tactic.group" ]
[]
https://github.com/leanprover-community/mathlib
65a1391a0106c9204fe45bc73a039f056558cb83
left_cancel (x : R) {y y' : R} : x ◃ y = x ◃ y' ↔ y = y'
by { split, apply (act x).injective, rintro rfl, refl }
lemma
rack.left_cancel
algebra
src/algebra/quandle.lean
[ "algebra.hom.equiv.basic", "algebra.hom.aut", "data.zmod.defs", "tactic.group" ]
[]
https://github.com/leanprover-community/mathlib
65a1391a0106c9204fe45bc73a039f056558cb83
left_cancel_inv (x : R) {y y' : R} : x ◃⁻¹ y = x ◃⁻¹ y' ↔ y = y'
by { split, apply (act x).symm.injective, rintro rfl, refl }
lemma
rack.left_cancel_inv
algebra
src/algebra/quandle.lean
[ "algebra.hom.equiv.basic", "algebra.hom.aut", "data.zmod.defs", "tactic.group" ]
[]
https://github.com/leanprover-community/mathlib
65a1391a0106c9204fe45bc73a039f056558cb83
self_distrib_inv {x y z : R} : x ◃⁻¹ y ◃⁻¹ z = (x ◃⁻¹ y) ◃⁻¹ (x ◃⁻¹ z)
begin rw [←left_cancel (x ◃⁻¹ y), right_inv, ←left_cancel x, right_inv, self_distrib], repeat {rw right_inv }, end
lemma
rack.self_distrib_inv
algebra
src/algebra/quandle.lean
[ "algebra.hom.equiv.basic", "algebra.hom.aut", "data.zmod.defs", "tactic.group" ]
[]
https://github.com/leanprover-community/mathlib
65a1391a0106c9204fe45bc73a039f056558cb83
ad_conj {R : Type*} [rack R] (x y : R) : act (x ◃ y) = act x * act y * (act x)⁻¹
begin rw [eq_mul_inv_iff_mul_eq], ext z, apply self_distrib.symm, end
lemma
rack.ad_conj
algebra
src/algebra/quandle.lean
[ "algebra.hom.equiv.basic", "algebra.hom.aut", "data.zmod.defs", "tactic.group" ]
[ "eq_mul_inv_iff_mul_eq", "rack" ]
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 `to_conj` from `R` to `conj (R ≃ R)` defined by `op'`.
https://github.com/leanprover-community/mathlib
65a1391a0106c9204fe45bc73a039f056558cb83
opposite_rack : rack Rᵐᵒᵖ
{ act := λ x y, op (inv_act (unop x) (unop y)), self_distrib := mul_opposite.rec $ λ x, mul_opposite.rec $ λ y, mul_opposite.rec $ λ z, begin simp only [unop_op, op_inj], exact self_distrib_inv, end, inv_act := λ x y, op (shelf.act (unop x) (unop y)), left_inv := mul_opposite.rec $ λ x, mul_opposite.rec...
instance
rack.opposite_rack
algebra
src/algebra/quandle.lean
[ "algebra.hom.equiv.basic", "algebra.hom.aut", "data.zmod.defs", "tactic.group" ]
[ "mul_opposite.rec", "rack" ]
The opposite rack, swapping the roles of `◃` and `◃⁻¹`.
https://github.com/leanprover-community/mathlib
65a1391a0106c9204fe45bc73a039f056558cb83
op_act_op_eq {x y : R} : (op x) ◃ (op y) = op (x ◃⁻¹ y)
rfl
lemma
rack.op_act_op_eq
algebra
src/algebra/quandle.lean
[ "algebra.hom.equiv.basic", "algebra.hom.aut", "data.zmod.defs", "tactic.group" ]
[]
https://github.com/leanprover-community/mathlib
65a1391a0106c9204fe45bc73a039f056558cb83
op_inv_act_op_eq {x y : R} : (op x) ◃⁻¹ (op y) = op (x ◃ y)
rfl
lemma
rack.op_inv_act_op_eq
algebra
src/algebra/quandle.lean
[ "algebra.hom.equiv.basic", "algebra.hom.aut", "data.zmod.defs", "tactic.group" ]
[]
https://github.com/leanprover-community/mathlib
65a1391a0106c9204fe45bc73a039f056558cb83
self_act_act_eq {x y : R} : (x ◃ x) ◃ y = x ◃ y
by { rw [←right_inv x y, ←self_distrib] }
lemma
rack.self_act_act_eq
algebra
src/algebra/quandle.lean
[ "algebra.hom.equiv.basic", "algebra.hom.aut", "data.zmod.defs", "tactic.group" ]
[]
https://github.com/leanprover-community/mathlib
65a1391a0106c9204fe45bc73a039f056558cb83
self_inv_act_inv_act_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 }
lemma
rack.self_inv_act_inv_act_eq
algebra
src/algebra/quandle.lean
[ "algebra.hom.equiv.basic", "algebra.hom.aut", "data.zmod.defs", "tactic.group" ]
[]
https://github.com/leanprover-community/mathlib
65a1391a0106c9204fe45bc73a039f056558cb83
self_act_inv_act_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 }
lemma
rack.self_act_inv_act_eq
algebra
src/algebra/quandle.lean
[ "algebra.hom.equiv.basic", "algebra.hom.aut", "data.zmod.defs", "tactic.group" ]
[]
https://github.com/leanprover-community/mathlib
65a1391a0106c9204fe45bc73a039f056558cb83
self_inv_act_act_eq {x y : R} : (x ◃⁻¹ x) ◃ y = x ◃ y
by { have h := @self_act_inv_act_eq _ _ (op x) (op y), simpa using h }
lemma
rack.self_inv_act_act_eq
algebra
src/algebra/quandle.lean
[ "algebra.hom.equiv.basic", "algebra.hom.aut", "data.zmod.defs", "tactic.group" ]
[]
https://github.com/leanprover-community/mathlib
65a1391a0106c9204fe45bc73a039f056558cb83
self_act_eq_iff_eq {x y : R} : x ◃ x = y ◃ y ↔ x = y
begin split, swap, rintro rfl, refl, intro h, transitivity (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], end
lemma
rack.self_act_eq_iff_eq
algebra
src/algebra/quandle.lean
[ "algebra.hom.equiv.basic", "algebra.hom.aut", "data.zmod.defs", "tactic.group" ]
[]
https://github.com/leanprover-community/mathlib
65a1391a0106c9204fe45bc73a039f056558cb83
self_inv_act_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 }
lemma
rack.self_inv_act_eq_iff_eq
algebra
src/algebra/quandle.lean
[ "algebra.hom.equiv.basic", "algebra.hom.aut", "data.zmod.defs", "tactic.group" ]
[]
https://github.com/leanprover-community/mathlib
65a1391a0106c9204fe45bc73a039f056558cb83
self_apply_equiv (R : Type*) [rack R] : R ≃ R
{ to_fun := λ x, x ◃ x, inv_fun := λ x, x ◃⁻¹ x, left_inv := λ x, by simp, right_inv := λ x, by simp }
def
rack.self_apply_equiv
algebra
src/algebra/quandle.lean
[ "algebra.hom.equiv.basic", "algebra.hom.aut", "data.zmod.defs", "tactic.group" ]
[ "inv_fun", "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/mathlib
65a1391a0106c9204fe45bc73a039f056558cb83
is_involutory (R : Type*) [rack R] : Prop
∀ x : R, function.involutive (shelf.act x)
def
rack.is_involutory
algebra
src/algebra/quandle.lean
[ "algebra.hom.equiv.basic", "algebra.hom.aut", "data.zmod.defs", "tactic.group" ]
[ "rack" ]
An involutory rack is one for which `rack.op R x` is an involution for every x.
https://github.com/leanprover-community/mathlib
65a1391a0106c9204fe45bc73a039f056558cb83
involutory_inv_act_eq_act {R : Type*} [rack R] (h : is_involutory R) (x y : R) : x ◃⁻¹ y = x ◃ y
begin rw [←left_cancel x, right_inv], exact ((h x).left_inverse y).symm, end
lemma
rack.involutory_inv_act_eq_act
algebra
src/algebra/quandle.lean
[ "algebra.hom.equiv.basic", "algebra.hom.aut", "data.zmod.defs", "tactic.group" ]
[ "rack" ]
https://github.com/leanprover-community/mathlib
65a1391a0106c9204fe45bc73a039f056558cb83
is_abelian (R : Type*) [rack R] : Prop
∀ (x y z w : R), (x ◃ y) ◃ (z ◃ w) = (x ◃ z) ◃ (y ◃ w)
def
rack.is_abelian
algebra
src/algebra/quandle.lean
[ "algebra.hom.equiv.basic", "algebra.hom.aut", "data.zmod.defs", "tactic.group" ]
[ "rack" ]
An abelian rack is one for which the mediality axiom holds.
https://github.com/leanprover-community/mathlib
65a1391a0106c9204fe45bc73a039f056558cb83
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 }
lemma
rack.assoc_iff_id
algebra
src/algebra/quandle.lean
[ "algebra.hom.equiv.basic", "algebra.hom.aut", "data.zmod.defs", "tactic.group" ]
[ "rack" ]
Associative racks are uninteresting.
https://github.com/leanprover-community/mathlib
65a1391a0106c9204fe45bc73a039f056558cb83
to_fun_eq_coe (f : S₁ →◃ S₂) : f.to_fun = f
rfl
lemma
shelf_hom.to_fun_eq_coe
algebra
src/algebra/quandle.lean
[ "algebra.hom.equiv.basic", "algebra.hom.aut", "data.zmod.defs", "tactic.group" ]
[]
https://github.com/leanprover-community/mathlib
65a1391a0106c9204fe45bc73a039f056558cb83
map_act (f : S₁ →◃ S₂) {x y : S₁} : f (x ◃ y) = f x ◃ f y
map_act' f
lemma
shelf_hom.map_act
algebra
src/algebra/quandle.lean
[ "algebra.hom.equiv.basic", "algebra.hom.aut", "data.zmod.defs", "tactic.group" ]
[]
https://github.com/leanprover-community/mathlib
65a1391a0106c9204fe45bc73a039f056558cb83
id (S : Type*) [shelf S] : S →◃ S
{ to_fun := id, map_act' := by simp }
def
shelf_hom.id
algebra
src/algebra/quandle.lean
[ "algebra.hom.equiv.basic", "algebra.hom.aut", "data.zmod.defs", "tactic.group" ]
[ "shelf" ]
The identity homomorphism
https://github.com/leanprover-community/mathlib
65a1391a0106c9204fe45bc73a039f056558cb83
inhabited (S : Type*) [shelf S] : inhabited (S →◃ S)
⟨id S⟩
instance
shelf_hom.inhabited
algebra
src/algebra/quandle.lean
[ "algebra.hom.equiv.basic", "algebra.hom.aut", "data.zmod.defs", "tactic.group" ]
[ "shelf" ]
https://github.com/leanprover-community/mathlib
65a1391a0106c9204fe45bc73a039f056558cb83
comp (g : S₂ →◃ S₃) (f : S₁ →◃ S₂) : S₁ →◃ S₃
{ to_fun := g.to_fun ∘ f.to_fun, map_act' := by simp }
def
shelf_hom.comp
algebra
src/algebra/quandle.lean
[ "algebra.hom.equiv.basic", "algebra.hom.aut", "data.zmod.defs", "tactic.group" ]
[]
The composition of shelf homomorphisms
https://github.com/leanprover-community/mathlib
65a1391a0106c9204fe45bc73a039f056558cb83
comp_apply (g : S₂ →◃ S₃) (f : S₁ →◃ S₂) (x : S₁) : (g.comp f) x = g (f x)
rfl
lemma
shelf_hom.comp_apply
algebra
src/algebra/quandle.lean
[ "algebra.hom.equiv.basic", "algebra.hom.aut", "data.zmod.defs", "tactic.group" ]
[]
https://github.com/leanprover-community/mathlib
65a1391a0106c9204fe45bc73a039f056558cb83
quandle (α : Type*) extends rack α
(fix : ∀ {x : α}, act x x = x)
class
quandle
algebra
src/algebra/quandle.lean
[ "algebra.hom.equiv.basic", "algebra.hom.aut", "data.zmod.defs", "tactic.group" ]
[ "rack" ]
A quandle is a rack such that each automorphism fixes its corresponding element.
https://github.com/leanprover-community/mathlib
65a1391a0106c9204fe45bc73a039f056558cb83
fix_inv {x : Q} : x ◃⁻¹ x = x
by { rw ←left_cancel x, simp }
lemma
quandle.fix_inv
algebra
src/algebra/quandle.lean
[ "algebra.hom.equiv.basic", "algebra.hom.aut", "data.zmod.defs", "tactic.group" ]
[]
https://github.com/leanprover-community/mathlib
65a1391a0106c9204fe45bc73a039f056558cb83
opposite_quandle : quandle Qᵐᵒᵖ
{ fix := λ x, by { induction x using mul_opposite.rec, simp } }
instance
quandle.opposite_quandle
algebra
src/algebra/quandle.lean
[ "algebra.hom.equiv.basic", "algebra.hom.aut", "data.zmod.defs", "tactic.group" ]
[ "mul_opposite.rec", "quandle" ]
https://github.com/leanprover-community/mathlib
65a1391a0106c9204fe45bc73a039f056558cb83
conj (G : Type*)
G
def
quandle.conj
algebra
src/algebra/quandle.lean
[ "algebra.hom.equiv.basic", "algebra.hom.aut", "data.zmod.defs", "tactic.group" ]
[]
The conjugation quandle of a group. Each element of the group acts by the corresponding inner automorphism.
https://github.com/leanprover-community/mathlib
65a1391a0106c9204fe45bc73a039f056558cb83
conj.quandle (G : Type*) [group G] : quandle (conj G)
{ act := (λ x, @mul_aut.conj G _ x), self_distrib := λ x y z, begin dsimp only [mul_equiv.coe_to_equiv, mul_aut.conj_apply, conj], group, end, inv_act := (λ x, (@mul_aut.conj G _ x).symm), left_inv := λ x y, by { dsimp [act, conj], group }, right_inv := λ x y, by { dsimp [act, conj], group }, fix :=...
instance
quandle.conj.quandle
algebra
src/algebra/quandle.lean
[ "algebra.hom.equiv.basic", "algebra.hom.aut", "data.zmod.defs", "tactic.group" ]
[ "group", "mul_aut.conj", "mul_aut.conj_apply", "mul_equiv.coe_to_equiv", "quandle" ]
https://github.com/leanprover-community/mathlib
65a1391a0106c9204fe45bc73a039f056558cb83
conj_act_eq_conj {G : Type*} [group G] (x y : conj G) : x ◃ y = ((x : G) * (y : G) * (x : G)⁻¹ : G)
rfl
lemma
quandle.conj_act_eq_conj
algebra
src/algebra/quandle.lean
[ "algebra.hom.equiv.basic", "algebra.hom.aut", "data.zmod.defs", "tactic.group" ]
[ "group" ]
https://github.com/leanprover-community/mathlib
65a1391a0106c9204fe45bc73a039f056558cb83
conj_swap {G : Type*} [group G] (x y : conj G) : x ◃ y = y ↔ y ◃ x = x
begin dsimp [conj] at *, split, repeat { intro h, conv_rhs { rw eq_mul_inv_of_mul_eq (eq_mul_inv_of_mul_eq h) }, simp, }, end
lemma
quandle.conj_swap
algebra
src/algebra/quandle.lean
[ "algebra.hom.equiv.basic", "algebra.hom.aut", "data.zmod.defs", "tactic.group" ]
[ "eq_mul_inv_of_mul_eq", "group" ]
https://github.com/leanprover-community/mathlib
65a1391a0106c9204fe45bc73a039f056558cb83
conj.map {G : Type*} {H : Type*} [group G] [group H] (f : G →* H) : conj G →◃ conj H
{ to_fun := f, map_act' := by simp }
def
quandle.conj.map
algebra
src/algebra/quandle.lean
[ "algebra.hom.equiv.basic", "algebra.hom.aut", "data.zmod.defs", "tactic.group" ]
[ "group" ]
`conj` is functorial
https://github.com/leanprover-community/mathlib
65a1391a0106c9204fe45bc73a039f056558cb83
dihedral (n : ℕ)
zmod n
def
quandle.dihedral
algebra
src/algebra/quandle.lean
[ "algebra.hom.equiv.basic", "algebra.hom.aut", "data.zmod.defs", "tactic.group" ]
[ "zmod" ]
The dihedral quandle. This is the conjugation quandle of the dihedral group restrict to flips. Used for Fox n-colorings of knots.
https://github.com/leanprover-community/mathlib
65a1391a0106c9204fe45bc73a039f056558cb83
dihedral_act (n : ℕ) (a : zmod n) : zmod n → zmod n
λ b, 2 * a - b
def
quandle.dihedral_act
algebra
src/algebra/quandle.lean
[ "algebra.hom.equiv.basic", "algebra.hom.aut", "data.zmod.defs", "tactic.group" ]
[ "zmod" ]
The operation for the dihedral quandle. It does not need to be an equivalence because it is an involution (see `dihedral_act.inv`).
https://github.com/leanprover-community/mathlib
65a1391a0106c9204fe45bc73a039f056558cb83
dihedral_act.inv (n : ℕ) (a : zmod n) : function.involutive (dihedral_act n a)
by { intro b, dsimp [dihedral_act], ring }
lemma
quandle.dihedral_act.inv
algebra
src/algebra/quandle.lean
[ "algebra.hom.equiv.basic", "algebra.hom.aut", "data.zmod.defs", "tactic.group" ]
[ "ring", "zmod" ]
https://github.com/leanprover-community/mathlib
65a1391a0106c9204fe45bc73a039f056558cb83
to_conj (R : Type*) [rack R] : R →◃ quandle.conj (R ≃ R)
{ to_fun := act, map_act' := ad_conj }
def
rack.to_conj
algebra
src/algebra/quandle.lean
[ "algebra.hom.equiv.basic", "algebra.hom.aut", "data.zmod.defs", "tactic.group" ]
[ "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/mathlib
65a1391a0106c9204fe45bc73a039f056558cb83
pre_envel_group (R : Type u) : Type u | unit : pre_envel_group | incl (x : R) : pre_envel_group | mul (a b : pre_envel_group) : pre_envel_group | inv (a : pre_envel_group) : pre_envel_group
inductive
rack.pre_envel_group
algebra
src/algebra/quandle.lean
[ "algebra.hom.equiv.basic", "algebra.hom.aut", "data.zmod.defs", "tactic.group" ]
[]
Free generators of the enveloping group.
https://github.com/leanprover-community/mathlib
65a1391a0106c9204fe45bc73a039f056558cb83
pre_envel_group.inhabited (R : Type u) : inhabited (pre_envel_group R)
⟨pre_envel_group.unit⟩
instance
rack.pre_envel_group.inhabited
algebra
src/algebra/quandle.lean
[ "algebra.hom.equiv.basic", "algebra.hom.aut", "data.zmod.defs", "tactic.group" ]
[]
https://github.com/leanprover-community/mathlib
65a1391a0106c9204fe45bc73a039f056558cb83
pre_envel_group_rel' (R : Type u) [rack R] : pre_envel_group R → pre_envel_group R → Type u | refl {a : pre_envel_group R} : pre_envel_group_rel' a a | symm {a b : pre_envel_group R} (hab : pre_envel_group_rel' a b) : pre_envel_group_rel' b a | trans {a b c : pre_envel_group R} (hab : pre_envel_group_rel' a b) (hbc...
inductive
rack.pre_envel_group_rel'
algebra
src/algebra/quandle.lean
[ "algebra.hom.equiv.basic", "algebra.hom.aut", "data.zmod.defs", "tactic.group" ]
[ "mul_left_inv", "mul_one", "one_mul", "rack" ]
Relations for the enveloping group. This is a type-valued relation because `to_envel_group.map_aux.well_def` inducts on it to show `to_envel_group.map` is well-defined. The relation `pre_envel_group_rel` is the `Prop`-valued version, which is used to define `envel_group` itself.
https://github.com/leanprover-community/mathlib
65a1391a0106c9204fe45bc73a039f056558cb83
pre_envel_group_rel'.inhabited (R : Type u) [rack R] : inhabited (pre_envel_group_rel' R unit unit)
⟨pre_envel_group_rel'.refl⟩
instance
rack.pre_envel_group_rel'.inhabited
algebra
src/algebra/quandle.lean
[ "algebra.hom.equiv.basic", "algebra.hom.aut", "data.zmod.defs", "tactic.group" ]
[ "rack" ]
https://github.com/leanprover-community/mathlib
65a1391a0106c9204fe45bc73a039f056558cb83
pre_envel_group_rel (R : Type u) [rack R] : pre_envel_group R → pre_envel_group R → Prop | rel {a b : pre_envel_group R} (r : pre_envel_group_rel' R a b) : pre_envel_group_rel a b
inductive
rack.pre_envel_group_rel
algebra
src/algebra/quandle.lean
[ "algebra.hom.equiv.basic", "algebra.hom.aut", "data.zmod.defs", "tactic.group" ]
[ "rack", "rel" ]
The `pre_envel_group_rel` relation as a `Prop`. Used as the relation for `pre_envel_group.setoid`.
https://github.com/leanprover-community/mathlib
65a1391a0106c9204fe45bc73a039f056558cb83
pre_envel_group_rel'.rel {R : Type u} [rack R] {a b : pre_envel_group R} : pre_envel_group_rel' R a b → pre_envel_group_rel R a b
pre_envel_group_rel.rel
lemma
rack.pre_envel_group_rel'.rel
algebra
src/algebra/quandle.lean
[ "algebra.hom.equiv.basic", "algebra.hom.aut", "data.zmod.defs", "tactic.group" ]
[ "rack" ]
A quick way to convert a `pre_envel_group_rel'` to a `pre_envel_group_rel`.
https://github.com/leanprover-community/mathlib
65a1391a0106c9204fe45bc73a039f056558cb83
pre_envel_group_rel.refl {R : Type u} [rack R] {a : pre_envel_group R} : pre_envel_group_rel R a a
pre_envel_group_rel.rel pre_envel_group_rel'.refl
lemma
rack.pre_envel_group_rel.refl
algebra
src/algebra/quandle.lean
[ "algebra.hom.equiv.basic", "algebra.hom.aut", "data.zmod.defs", "tactic.group" ]
[ "rack" ]
https://github.com/leanprover-community/mathlib
65a1391a0106c9204fe45bc73a039f056558cb83
pre_envel_group_rel.symm {R : Type u} [rack R] {a b : pre_envel_group R} : pre_envel_group_rel R a b → pre_envel_group_rel R b a
| ⟨r⟩ := r.symm.rel
lemma
rack.pre_envel_group_rel.symm
algebra
src/algebra/quandle.lean
[ "algebra.hom.equiv.basic", "algebra.hom.aut", "data.zmod.defs", "tactic.group" ]
[ "rack" ]
https://github.com/leanprover-community/mathlib
65a1391a0106c9204fe45bc73a039f056558cb83
pre_envel_group_rel.trans {R : Type u} [rack R] {a b c : pre_envel_group R} : pre_envel_group_rel R a b → pre_envel_group_rel R b c → pre_envel_group_rel R a c
| ⟨rab⟩ ⟨rbc⟩ := (rab.trans rbc).rel
lemma
rack.pre_envel_group_rel.trans
algebra
src/algebra/quandle.lean
[ "algebra.hom.equiv.basic", "algebra.hom.aut", "data.zmod.defs", "tactic.group" ]
[ "rack", "rel" ]
https://github.com/leanprover-community/mathlib
65a1391a0106c9204fe45bc73a039f056558cb83
pre_envel_group.setoid (R : Type*) [rack R] : setoid (pre_envel_group R)
{ r := pre_envel_group_rel R, iseqv := begin split, apply pre_envel_group_rel.refl, split, apply pre_envel_group_rel.symm, apply pre_envel_group_rel.trans end }
instance
rack.pre_envel_group.setoid
algebra
src/algebra/quandle.lean
[ "algebra.hom.equiv.basic", "algebra.hom.aut", "data.zmod.defs", "tactic.group" ]
[ "rack" ]
https://github.com/leanprover-community/mathlib
65a1391a0106c9204fe45bc73a039f056558cb83
envel_group (R : Type*) [rack R]
quotient (pre_envel_group.setoid R)
def
rack.envel_group
algebra
src/algebra/quandle.lean
[ "algebra.hom.equiv.basic", "algebra.hom.aut", "data.zmod.defs", "tactic.group" ]
[ "rack" ]
The universal enveloping group for the rack R.
https://github.com/leanprover-community/mathlib
65a1391a0106c9204fe45bc73a039f056558cb83
envel_group.inhabited (R : Type*) [rack R] : inhabited (envel_group R)
⟨1⟩
instance
rack.envel_group.inhabited
algebra
src/algebra/quandle.lean
[ "algebra.hom.equiv.basic", "algebra.hom.aut", "data.zmod.defs", "tactic.group" ]
[ "rack" ]
https://github.com/leanprover-community/mathlib
65a1391a0106c9204fe45bc73a039f056558cb83
to_envel_group (R : Type*) [rack R] : R →◃ quandle.conj (envel_group R)
{ to_fun := λ x, ⟦incl x⟧, map_act' := λ x y, quotient.sound (pre_envel_group_rel'.act_incl x y).symm.rel }
def
rack.to_envel_group
algebra
src/algebra/quandle.lean
[ "algebra.hom.equiv.basic", "algebra.hom.aut", "data.zmod.defs", "tactic.group" ]
[ "quandle.conj", "rack" ]
The canonical homomorphism from a rack to its enveloping group. Satisfies universal properties given by `to_envel_group.map` and `to_envel_group.univ`.
https://github.com/leanprover-community/mathlib
65a1391a0106c9204fe45bc73a039f056558cb83
to_envel_group.map_aux {R : Type*} [rack R] {G : Type*} [group G] (f : R →◃ quandle.conj G) : pre_envel_group R → G
| unit := 1 | (incl x) := f x | (mul a b) := to_envel_group.map_aux a * to_envel_group.map_aux b | (inv a) := (to_envel_group.map_aux a)⁻¹
def
rack.to_envel_group.map_aux
algebra
src/algebra/quandle.lean
[ "algebra.hom.equiv.basic", "algebra.hom.aut", "data.zmod.defs", "tactic.group" ]
[ "group", "quandle.conj", "rack" ]
The preliminary definition of the induced map from the enveloping group. See `to_envel_group.map`.
https://github.com/leanprover-community/mathlib
65a1391a0106c9204fe45bc73a039f056558cb83
well_def {R : Type*} [rack R] {G : Type*} [group G] (f : R →◃ quandle.conj G) : Π {a b : pre_envel_group R}, pre_envel_group_rel' R a b → to_envel_group.map_aux f a = to_envel_group.map_aux f b
| a b refl := rfl | a b (symm h) := (well_def h).symm | a b (trans hac hcb) := eq.trans (well_def hac) (well_def hcb) | _ _ (congr_mul ha hb) := by { simp [to_envel_group.map_aux, well_def ha, well_def hb] } | _ _ (congr_inv ha) := by { simp [to_envel_group.map_aux, well_def ha] } | _ _ (assoc a b c) := by { apply mul_...
lemma
rack.to_envel_group.map_aux.well_def
algebra
src/algebra/quandle.lean
[ "algebra.hom.equiv.basic", "algebra.hom.aut", "data.zmod.defs", "tactic.group" ]
[ "group", "mul_assoc", "mul_left_inv", "mul_one", "one_mul", "quandle.conj", "rack" ]
Show that `to_envel_group.map_aux` sends equivalent expressions to equal terms.
https://github.com/leanprover-community/mathlib
65a1391a0106c9204fe45bc73a039f056558cb83
to_envel_group.map {R : Type*} [rack R] {G : Type*} [group G] : (R →◃ quandle.conj G) ≃ (envel_group R →* G)
{ to_fun := λ f, { to_fun := λ x, quotient.lift_on x (to_envel_group.map_aux f) (λ a b ⟨hab⟩, to_envel_group.map_aux.well_def f hab), map_one' := begin change quotient.lift_on ⟦rack.pre_envel_group.unit⟧ (to_envel_group.map_aux f) _ = 1, simp [to_envel_group.map_aux], end, ...
def
rack.to_envel_group.map
algebra
src/algebra/quandle.lean
[ "algebra.hom.equiv.basic", "algebra.hom.aut", "data.zmod.defs", "tactic.group" ]
[ "group", "inv_fun", "monoid_hom.ext", "monoid_hom.map_inv", "monoid_hom.map_mul", "quandle.conj", "quandle.conj.map", "rack" ]
Given a map from a rack to a group, lift it to being a map from the enveloping group. More precisely, the `envel_group` functor is left adjoint to `quandle.conj`.
https://github.com/leanprover-community/mathlib
65a1391a0106c9204fe45bc73a039f056558cb83
to_envel_group.univ (R : Type*) [rack R] (G : Type*) [group G] (f : R →◃ quandle.conj G) : (quandle.conj.map (to_envel_group.map f)).comp (to_envel_group R) = f
to_envel_group.map.symm_apply_apply f
lemma
rack.to_envel_group.univ
algebra
src/algebra/quandle.lean
[ "algebra.hom.equiv.basic", "algebra.hom.aut", "data.zmod.defs", "tactic.group" ]
[ "group", "quandle.conj", "quandle.conj.map", "rack" ]
Given a homomorphism from a rack to a group, it factors through the enveloping group.
https://github.com/leanprover-community/mathlib
65a1391a0106c9204fe45bc73a039f056558cb83
to_envel_group.univ_uniq (R : Type*) [rack R] (G : Type*) [group G] (f : R →◃ quandle.conj G) (g : envel_group R →* G) (h : f = (quandle.conj.map g).comp (to_envel_group R)) : g = to_envel_group.map f
h.symm ▸ (to_envel_group.map.apply_symm_apply g).symm
lemma
rack.to_envel_group.univ_uniq
algebra
src/algebra/quandle.lean
[ "algebra.hom.equiv.basic", "algebra.hom.aut", "data.zmod.defs", "tactic.group" ]
[ "group", "quandle.conj", "quandle.conj.map", "rack" ]
The homomorphism `to_envel_group.map f` is the unique map that fits into the commutative triangle in `to_envel_group.univ`.
https://github.com/leanprover-community/mathlib
65a1391a0106c9204fe45bc73a039f056558cb83
envel_action {R : Type*} [rack R] : envel_group R →* (R ≃ R)
to_envel_group.map (to_conj R)
def
rack.envel_action
algebra
src/algebra/quandle.lean
[ "algebra.hom.equiv.basic", "algebra.hom.aut", "data.zmod.defs", "tactic.group" ]
[ "rack" ]
The induced group homomorphism from the enveloping group into bijections of the rack, using `rack.to_conj`. Satisfies the property `envel_action_prop`. This gives the rack `R` the structure of an augmented rack over `envel_group R`.
https://github.com/leanprover-community/mathlib
65a1391a0106c9204fe45bc73a039f056558cb83
envel_action_prop {R : Type*} [rack R] (x y : R) : envel_action (to_envel_group R x) y = x ◃ y
rfl
lemma
rack.envel_action_prop
algebra
src/algebra/quandle.lean
[ "algebra.hom.equiv.basic", "algebra.hom.aut", "data.zmod.defs", "tactic.group" ]
[ "rack" ]
https://github.com/leanprover-community/mathlib
65a1391a0106c9204fe45bc73a039f056558cb83
quaternion_algebra (R : Type*) (a b : R)
mk {} :: (re : R) (im_i : R) (im_j : R) (im_k : R)
structure
quaternion_algebra
algebra
src/algebra/quaternion.lean
[ "algebra.algebra.equiv", "linear_algebra.finrank", "linear_algebra.free_module.basic", "linear_algebra.free_module.finite.basic", "set_theory.cardinal.ordinal", "tactic.ring_exp" ]
[]
Quaternion algebra over a type with fixed coefficients $a=i^2$ and $b=j^2$. Implemented as a structure with four fields: `re`, `im_i`, `im_j`, and `im_k`.
https://github.com/leanprover-community/mathlib
65a1391a0106c9204fe45bc73a039f056558cb83
equiv_prod {R : Type*} (c₁ c₂ : R) : ℍ[R, c₁, c₂] ≃ R × R × R × R
{ to_fun := λ a, ⟨a.1, a.2, a.3, a.4⟩, inv_fun := λ a, ⟨a.1, a.2.1, a.2.2.1, a.2.2.2⟩, left_inv := λ ⟨a₁, a₂, a₃, a₄⟩, rfl, right_inv := λ ⟨a₁, a₂, a₃, a₄⟩, rfl }
def
quaternion_algebra.equiv_prod
algebra
src/algebra/quaternion.lean
[ "algebra.algebra.equiv", "linear_algebra.finrank", "linear_algebra.free_module.basic", "linear_algebra.free_module.finite.basic", "set_theory.cardinal.ordinal", "tactic.ring_exp" ]
[ "inv_fun" ]
The equivalence between a quaternion algebra over R and R × R × R × R.
https://github.com/leanprover-community/mathlib
65a1391a0106c9204fe45bc73a039f056558cb83
equiv_tuple {R : Type*} (c₁ c₂ : R) : ℍ[R, c₁, c₂] ≃ (fin 4 → R)
{ to_fun := λ a, ![a.1, a.2, a.3, a.4], inv_fun := λ a, ⟨a 0, a 1, a 2, a 3⟩, left_inv := λ ⟨a₁, a₂, a₃, a₄⟩, rfl, right_inv := λ f, by ext ⟨_, _|_|_|_|_|⟨⟩⟩; refl }
def
quaternion_algebra.equiv_tuple
algebra
src/algebra/quaternion.lean
[ "algebra.algebra.equiv", "linear_algebra.finrank", "linear_algebra.free_module.basic", "linear_algebra.free_module.finite.basic", "set_theory.cardinal.ordinal", "tactic.ring_exp" ]
[ "inv_fun" ]
The equivalence between a quaternion algebra over `R` and `fin 4 → R`.
https://github.com/leanprover-community/mathlib
65a1391a0106c9204fe45bc73a039f056558cb83
equiv_tuple_apply {R : Type*} (c₁ c₂ : R) (x : ℍ[R, c₁, c₂]) : equiv_tuple c₁ c₂ x = ![x.re, x.im_i, x.im_j, x.im_k]
rfl
lemma
quaternion_algebra.equiv_tuple_apply
algebra
src/algebra/quaternion.lean
[ "algebra.algebra.equiv", "linear_algebra.finrank", "linear_algebra.free_module.basic", "linear_algebra.free_module.finite.basic", "set_theory.cardinal.ordinal", "tactic.ring_exp" ]
[]
https://github.com/leanprover-community/mathlib
65a1391a0106c9204fe45bc73a039f056558cb83
mk.eta {R : Type*} {c₁ c₂} : ∀ a : ℍ[R, c₁, c₂], mk a.1 a.2 a.3 a.4 = a
| ⟨a₁, a₂, a₃, a₄⟩ := rfl
lemma
quaternion_algebra.mk.eta
algebra
src/algebra/quaternion.lean
[ "algebra.algebra.equiv", "linear_algebra.finrank", "linear_algebra.free_module.basic", "linear_algebra.free_module.finite.basic", "set_theory.cardinal.ordinal", "tactic.ring_exp" ]
[]
https://github.com/leanprover-community/mathlib
65a1391a0106c9204fe45bc73a039f056558cb83
im (x : ℍ[R, c₁, c₂]) : ℍ[R, c₁, c₂]
⟨0, x.im_i, x.im_j, x.im_k⟩
def
quaternion_algebra.im
algebra
src/algebra/quaternion.lean
[ "algebra.algebra.equiv", "linear_algebra.finrank", "linear_algebra.free_module.basic", "linear_algebra.free_module.finite.basic", "set_theory.cardinal.ordinal", "tactic.ring_exp" ]
[]
The imaginary part of a quaternion.
https://github.com/leanprover-community/mathlib
65a1391a0106c9204fe45bc73a039f056558cb83
im_re : a.im.re = 0
rfl
lemma
quaternion_algebra.im_re
algebra
src/algebra/quaternion.lean
[ "algebra.algebra.equiv", "linear_algebra.finrank", "linear_algebra.free_module.basic", "linear_algebra.free_module.finite.basic", "set_theory.cardinal.ordinal", "tactic.ring_exp" ]
[]
https://github.com/leanprover-community/mathlib
65a1391a0106c9204fe45bc73a039f056558cb83
im_im_i : a.im.im_i = a.im_i
rfl
lemma
quaternion_algebra.im_im_i
algebra
src/algebra/quaternion.lean
[ "algebra.algebra.equiv", "linear_algebra.finrank", "linear_algebra.free_module.basic", "linear_algebra.free_module.finite.basic", "set_theory.cardinal.ordinal", "tactic.ring_exp" ]
[]
https://github.com/leanprover-community/mathlib
65a1391a0106c9204fe45bc73a039f056558cb83
im_im_j : a.im.im_j = a.im_j
rfl
lemma
quaternion_algebra.im_im_j
algebra
src/algebra/quaternion.lean
[ "algebra.algebra.equiv", "linear_algebra.finrank", "linear_algebra.free_module.basic", "linear_algebra.free_module.finite.basic", "set_theory.cardinal.ordinal", "tactic.ring_exp" ]
[]
https://github.com/leanprover-community/mathlib
65a1391a0106c9204fe45bc73a039f056558cb83
im_im_k : a.im.im_k = a.im_k
rfl
lemma
quaternion_algebra.im_im_k
algebra
src/algebra/quaternion.lean
[ "algebra.algebra.equiv", "linear_algebra.finrank", "linear_algebra.free_module.basic", "linear_algebra.free_module.finite.basic", "set_theory.cardinal.ordinal", "tactic.ring_exp" ]
[]
https://github.com/leanprover-community/mathlib
65a1391a0106c9204fe45bc73a039f056558cb83
im_idem : a.im.im = a.im
rfl
lemma
quaternion_algebra.im_idem
algebra
src/algebra/quaternion.lean
[ "algebra.algebra.equiv", "linear_algebra.finrank", "linear_algebra.free_module.basic", "linear_algebra.free_module.finite.basic", "set_theory.cardinal.ordinal", "tactic.ring_exp" ]
[]
https://github.com/leanprover-community/mathlib
65a1391a0106c9204fe45bc73a039f056558cb83
coe_re : (x : ℍ[R, c₁, c₂]).re = x
rfl
lemma
quaternion_algebra.coe_re
algebra
src/algebra/quaternion.lean
[ "algebra.algebra.equiv", "linear_algebra.finrank", "linear_algebra.free_module.basic", "linear_algebra.free_module.finite.basic", "set_theory.cardinal.ordinal", "tactic.ring_exp" ]
[]
https://github.com/leanprover-community/mathlib
65a1391a0106c9204fe45bc73a039f056558cb83
coe_im_i : (x : ℍ[R, c₁, c₂]).im_i = 0
rfl
lemma
quaternion_algebra.coe_im_i
algebra
src/algebra/quaternion.lean
[ "algebra.algebra.equiv", "linear_algebra.finrank", "linear_algebra.free_module.basic", "linear_algebra.free_module.finite.basic", "set_theory.cardinal.ordinal", "tactic.ring_exp" ]
[]
https://github.com/leanprover-community/mathlib
65a1391a0106c9204fe45bc73a039f056558cb83
coe_im_j : (x : ℍ[R, c₁, c₂]).im_j = 0
rfl
lemma
quaternion_algebra.coe_im_j
algebra
src/algebra/quaternion.lean
[ "algebra.algebra.equiv", "linear_algebra.finrank", "linear_algebra.free_module.basic", "linear_algebra.free_module.finite.basic", "set_theory.cardinal.ordinal", "tactic.ring_exp" ]
[]
https://github.com/leanprover-community/mathlib
65a1391a0106c9204fe45bc73a039f056558cb83
coe_im_k : (x : ℍ[R, c₁, c₂]).im_k = 0
rfl
lemma
quaternion_algebra.coe_im_k
algebra
src/algebra/quaternion.lean
[ "algebra.algebra.equiv", "linear_algebra.finrank", "linear_algebra.free_module.basic", "linear_algebra.free_module.finite.basic", "set_theory.cardinal.ordinal", "tactic.ring_exp" ]
[]
https://github.com/leanprover-community/mathlib
65a1391a0106c9204fe45bc73a039f056558cb83
coe_injective : function.injective (coe : R → ℍ[R, c₁, c₂])
λ x y h, congr_arg re h
lemma
quaternion_algebra.coe_injective
algebra
src/algebra/quaternion.lean
[ "algebra.algebra.equiv", "linear_algebra.finrank", "linear_algebra.free_module.basic", "linear_algebra.free_module.finite.basic", "set_theory.cardinal.ordinal", "tactic.ring_exp" ]
[]
https://github.com/leanprover-community/mathlib
65a1391a0106c9204fe45bc73a039f056558cb83
coe_inj {x y : R} : (x : ℍ[R, c₁, c₂]) = y ↔ x = y
coe_injective.eq_iff
lemma
quaternion_algebra.coe_inj
algebra
src/algebra/quaternion.lean
[ "algebra.algebra.equiv", "linear_algebra.finrank", "linear_algebra.free_module.basic", "linear_algebra.free_module.finite.basic", "set_theory.cardinal.ordinal", "tactic.ring_exp" ]
[]
https://github.com/leanprover-community/mathlib
65a1391a0106c9204fe45bc73a039f056558cb83
coe_zero : ((0 : R) : ℍ[R, c₁, c₂]) = 0
rfl
lemma
quaternion_algebra.coe_zero
algebra
src/algebra/quaternion.lean
[ "algebra.algebra.equiv", "linear_algebra.finrank", "linear_algebra.free_module.basic", "linear_algebra.free_module.finite.basic", "set_theory.cardinal.ordinal", "tactic.ring_exp" ]
[]
https://github.com/leanprover-community/mathlib
65a1391a0106c9204fe45bc73a039f056558cb83
coe_one : ((1 : R) : ℍ[R, c₁, c₂]) = 1
rfl
lemma
quaternion_algebra.coe_one
algebra
src/algebra/quaternion.lean
[ "algebra.algebra.equiv", "linear_algebra.finrank", "linear_algebra.free_module.basic", "linear_algebra.free_module.finite.basic", "set_theory.cardinal.ordinal", "tactic.ring_exp" ]
[]
https://github.com/leanprover-community/mathlib
65a1391a0106c9204fe45bc73a039f056558cb83