Associated elements. #
In this file we define an equivalence relation Associated
saying that two elements of a monoid differ by a multiplication by a unit.
Then we show that the quotient type Associates
is a monoid
and prove basic properties of this quotient.
Two elements of a Monoid
are Associated
if one of them is another one
multiplied by a unit on the right.
Equations
- Associated x y = ∃ (u : Mˣ), x * ↑u = y
Instances For
The setoid of the relation x ~ᵤ y
iff there is a unit u
such that x * u = y
Equations
- Associated.setoid M = { r := Associated, iseqv := ⋯ }
Instances For
Equations
- instDecidableRelAssociatedOfDvd x✝¹ x✝ = decidable_of_iff (x✝¹ ∣ x✝ ∧ x✝ ∣ x✝¹) ⋯
See also Irreducible.coprime_iff_not_dvd
.
The quotient of a monoid by the Associated
relation. Two elements x
and y
are associated iff there is a unit u
such that x * u = y
. There is a natural
monoid structure on Associates M
.
Equations
- Associates M = Quotient (Associated.setoid M)
Instances For
The canonical quotient map from a monoid M
into the Associates
of M
Equations
- Associates.mk a = ⟦a⟧
Instances For
Equations
- Associates.instInhabited = { default := ⟦1⟧ }
Equations
- Associates.instOne = { one := ⟦1⟧ }
Equations
- Associates.instBot = { bot := 1 }
Equations
- Associates.instUniqueOfSubsingleton = { default := 1, uniq := ⋯ }
Equations
- Associates.instMul = { mul := Quotient.map₂ (fun (x1 x2 : M) => x1 * x2) ⋯ }
Equations
- Associates.instCommMonoid = CommMonoid.mk ⋯
Equations
- Associates.instPreorder = Preorder.mk ⋯ ⋯ ⋯
Associates.mk
as a MonoidHom
.
Equations
- Associates.mkMonoidHom = { toFun := Associates.mk, map_one' := ⋯, map_mul' := ⋯ }
Instances For
Equations
- Associates.uniqueUnits = { toInhabited := Units.instInhabited, uniq := ⋯ }
Alias of mul_eq_one
.
Alias of Subsingleton.elim
.
Equations
- Associates.instOrderBot = OrderBot.mk ⋯
Alias of Associates.mk_le_mk_iff_dvd
.
Alias of Associates.isPrimal_mk
.
Equations
- Associates.instZero = { zero := ⟦0⟧ }
Equations
- Associates.instTopOfZero = { top := 0 }
Equations
- Associates.instCommMonoidWithZero = CommMonoidWithZero.mk ⋯ ⋯
Equations
- Associates.instOrderTop = OrderTop.mk ⋯
Equations
- Associates.instBoundedOrder = BoundedOrder.mk
Equations
- a.instDecidableRelDvd b = Quotient.recOnSubsingleton₂ a b fun (x x_1 : M) => decidable_of_iff' (x ∣ x_1) ⋯
Equations
- Associates.instPartialOrder = PartialOrder.mk ⋯
Equations
- Associates.instCancelCommMonoidWithZero = CancelCommMonoidWithZero.mk