Free constructions #
Main definitions #
FreeMagma α: free magma (structure with binary operation without any axioms) over alphabetα, defined inductively, with traversable instance and decidable equality.MagmaAssocQuotient α: quotient of a magmaαby the associativity equivalence relation.FreeSemigroup α: free semigroup over alphabetα, defined as a structure with two fieldshead : αandtail : List α(i.e. nonempty lists), with traversable instance and decidable equality.FreeMagmaAssocQuotientEquiv α: isomorphism betweenMagmaAssocQuotient (FreeMagma α)andFreeSemigroup α.FreeMagma.lift: the universal property of the free magma, expressing its adjointness.
Free nonabelian additive magma over a given alphabet.
- of {α : Type u} : α → FreeAddMagma α
- add {α : Type u} : FreeAddMagma α → FreeAddMagma α → FreeAddMagma α
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Equations
Equations
- FreeMagma.instInhabited = { default := FreeMagma.of default }
Equations
- FreeAddMagma.instInhabited = { default := FreeAddMagma.of default }
Equations
- FreeMagma.instMul = { mul := FreeMagma.mul }
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- FreeAddMagma.instAdd = { add := FreeAddMagma.add }
Recursor for FreeMagma using x * y instead of FreeMagma.mul x y.
Equations
- x.recOnMul ih1 ih2 = FreeMagma.recOn x ih1 ih2
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Recursor for FreeAddMagma using x + y instead of FreeAddMagma.add x y.
Equations
- x.recOnAdd ih1 ih2 = FreeAddMagma.recOn x ih1 ih2
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Lifts a function α → β to a magma homomorphism FreeMagma α → β given a magma β.
Equations
- FreeMagma.liftAux f (FreeMagma.of x_1) = f x_1
- FreeMagma.liftAux f (x_1.mul y) = FreeMagma.liftAux f x_1 * FreeMagma.liftAux f y
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Lifts a function α → β to an additive magma homomorphism FreeAddMagma α → β given
an additive magma β.
Equations
- FreeAddMagma.liftAux f (FreeAddMagma.of x_1) = f x_1
- FreeAddMagma.liftAux f (x_1.add y) = FreeAddMagma.liftAux f x_1 + FreeAddMagma.liftAux f y
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The universal property of the free magma expressing its adjointness.
Equations
- FreeMagma.lift = { toFun := fun (f : α → β) => { toFun := FreeMagma.liftAux f, map_mul' := ⋯ }, invFun := fun (F : FreeMagma α →ₙ* β) => ⇑F ∘ FreeMagma.of, left_inv := ⋯, right_inv := ⋯ }
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The universal property of the free additive magma expressing its adjointness.
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- One or more equations did not get rendered due to their size.
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The unique additive magma homomorphism FreeAddMagma α → FreeAddMagma β that sends
each of x to of (f x).
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Recursor on FreeAddMagma using pure instead of of.
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FreeMagma is traversable.
Equations
- FreeMagma.traverse F (FreeMagma.of x_1) = FreeMagma.of <$> F x_1
- FreeMagma.traverse F (x_1.mul y) = (fun (x1 x2 : FreeMagma β) => x1 * x2) <$> FreeMagma.traverse F x_1 <*> FreeMagma.traverse F y
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FreeAddMagma is traversable.
Equations
- FreeAddMagma.traverse F (FreeAddMagma.of x_1) = FreeAddMagma.of <$> F x_1
- FreeAddMagma.traverse F (x_1.add y) = (fun (x1 x2 : FreeAddMagma β) => x1 + x2) <$> FreeAddMagma.traverse F x_1 <*> FreeAddMagma.traverse F y
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Representation of an element of a free magma.
Equations
- (FreeMagma.of x_1).repr = repr x_1
- (x_1.mul y).repr = Std.Format.text "( " ++ x_1.repr ++ Std.Format.text " * " ++ y.repr ++ Std.Format.text " )"
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Representation of an element of a free additive magma.
Equations
- (FreeAddMagma.of x_1).repr = repr x_1
- (x_1.add y).repr = Std.Format.text "( " ++ x_1.repr ++ Std.Format.text " + " ++ y.repr ++ Std.Format.text " )"
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Equations
- instReprFreeAddMagma = { reprPrec := fun (o : FreeAddMagma α) (x : ℕ) => o.repr }
Length of an element of a free additive magma.
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The length of an element of a free additive magma is positive.
Semigroup quotient of a magma.
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Additive semigroup quotient of an additive magma.
Equations
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Embedding from magma to its free semigroup.
Equations
- Magma.AssocQuotient.of = { toFun := Quot.mk (Magma.AssocRel α), map_mul' := ⋯ }
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Embedding from additive magma to its free additive semigroup.
Equations
- AddMagma.FreeAddSemigroup.of = { toFun := Quot.mk (AddMagma.AssocRel α), map_add' := ⋯ }
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- Magma.AssocQuotient.instInhabited = { default := Magma.AssocQuotient.of default }
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Lifts a magma homomorphism α → β to a semigroup homomorphism Magma.AssocQuotient α → β
given a semigroup β.
Equations
- One or more equations did not get rendered due to their size.
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Lifts an additive magma homomorphism α → β to an
additive semigroup homomorphism AddMagma.AssocQuotient α → β given an additive semigroup β.
Equations
- One or more equations did not get rendered due to their size.
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From a magma homomorphism α →ₙ* β to a semigroup homomorphism
Magma.AssocQuotient α →ₙ* Magma.AssocQuotient β.
Equations
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From an additive magma homomorphism α → β to an additive semigroup homomorphism
AddMagma.AssocQuotient α → AddMagma.AssocQuotient β.
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Free additive semigroup over a given alphabet.
- head : α
The head of the element
- tail : List α
The tail of the element
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Free semigroup over a given alphabet.
- head : α
The head of the element
- tail : List α
The tail of the element
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Equations
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The embedding α → FreeSemigroup α.
Equations
- FreeSemigroup.of x = { head := x, tail := [] }
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The embedding α → FreeAddSemigroup α.
Equations
- FreeAddSemigroup.of x = { head := x, tail := [] }
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Length of an element of free semigroup.
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Length of an element of free additive semigroup
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Equations
- FreeSemigroup.instInhabited = { default := FreeSemigroup.of default }
Equations
- FreeAddSemigroup.instInhabited = { default := FreeAddSemigroup.of default }
Recursor for free semigroup using of and *.
Equations
- One or more equations did not get rendered due to their size.
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Recursor for free additive semigroup using of and +.
Equations
- One or more equations did not get rendered due to their size.
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Lifts a function α → β to a semigroup homomorphism FreeSemigroup α → β given
a semigroup β.
Equations
- One or more equations did not get rendered due to their size.
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Lifts a function α → β to an additive semigroup
homomorphism FreeAddSemigroup α → β given an additive semigroup β.
Equations
- One or more equations did not get rendered due to their size.
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The unique additive semigroup homomorphism that sends of x to of (f x).
Equations
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Recursor that uses pure instead of of.
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Recursor that uses pure instead of of.
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FreeSemigroup is traversable.
Equations
- One or more equations did not get rendered due to their size.
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FreeAddSemigroup is traversable.
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- One or more equations did not get rendered due to their size.
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Equations
- x✝¹.instDecidableEq x✝ = decidable_of_iff' (x✝¹.head = x✝.head ∧ x✝¹.tail = x✝.tail) ⋯
Equations
- x✝¹.instDecidableEq x✝ = decidable_of_iff' (x✝¹.head = x✝.head ∧ x✝¹.tail = x✝.tail) ⋯
The canonical multiplicative morphism from FreeMagma α to FreeSemigroup α.
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The canonical additive morphism from FreeAddMagma α to FreeAddSemigroup α.
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Isomorphism between AddMagma.AssocQuotient (FreeAddMagma α) and
FreeAddSemigroup α.