Linearly ordered commutative groups and monoids with a zero element adjoined #
This file sets up a special class of linearly ordered commutative monoids that show up as the target of so-called “valuations” in algebraic number theory.
Usually, in the informal literature, these objects are constructed by taking a linearly ordered commutative group Γ and formally adjoining a zero element: Γ ∪ {0}.
The disadvantage is that a type such as NNReal
is not of that form,
whereas it is a very common target for valuations.
The solutions is to use a typeclass, and that is exactly what we do in this file.
Note that to avoid issues with import cycles, LinearOrderedCommMonoidWithZero
is defined
in another file. However, the lemmas about it are stated here.
A linearly ordered commutative group with a zero element.
- mul : α → α → α
- one : α
- npow : ℕ → α → α
- npow_zero : ∀ (x : α), Monoid.npow 0 x = 1
- npow_succ : ∀ (n : ℕ) (x : α), Monoid.npow (n + 1) x = x * Monoid.npow n x
- le : α → α → Prop
- lt : α → α → Prop
- le_refl : ∀ (a : α), a ≤ a
- min : α → α → α
- max : α → α → α
- compare : α → α → Ordering
- decidableLE : DecidableRel fun (x x_1 : α) => x ≤ x_1
- decidableEq : DecidableEq α
- decidableLT : DecidableRel fun (x x_1 : α) => x < x_1
- compare_eq_compareOfLessAndEq : ∀ (a b : α), compare a b = compareOfLessAndEq a b
- zero : α
- zero_le_one : 0 ≤ 1
- inv : α → α
- div : α → α → α
a / b := a * b⁻¹
- zpow : ℤ → α → α
The power operation:
a ^ n = a * ··· * a
;a ^ (-n) = a⁻¹ * ··· a⁻¹
(n
times) - zpow_zero' : ∀ (a : α), LinearOrderedCommGroupWithZero.zpow 0 a = 1
a ^ 0 = 1
- zpow_succ' : ∀ (n : ℕ) (a : α), LinearOrderedCommGroupWithZero.zpow (Int.ofNat (Nat.succ n)) a = a * LinearOrderedCommGroupWithZero.zpow (Int.ofNat n) a
a ^ (n + 1) = a * a ^ n
- zpow_neg' : ∀ (n : ℕ) (a : α), LinearOrderedCommGroupWithZero.zpow (Int.negSucc n) a = (LinearOrderedCommGroupWithZero.zpow (↑(Nat.succ n)) a)⁻¹
a ^ -(n + 1) = (a ^ (n + 1))⁻¹
- exists_pair_ne : ∃ (x : α), ∃ (y : α), x ≠ y
The inverse of
0
in a group with zero is0
.Every nonzero element of a group with zero is invertible.
Instances
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Pullback a LinearOrderedCommMonoidWithZero
under an injective map.
See note [reducible non-instances].
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Alias of mul_le_one'
for unification.
Alias of one_le_mul'
for unification.
Equiv.mulLeft₀
as an OrderIso
on a LinearOrderedCommGroupWithZero.
.
Note that OrderIso.mulLeft₀
refers to the LinearOrderedField
version.
Equations
- OrderIso.mulLeft₀' ha = let src := Equiv.mulLeft₀ a ha; { toEquiv := src, map_rel_iff' := (_ : ∀ {a_1 b : α}, ↑(Units.mk0 a ha) * a_1 ≤ ↑(Units.mk0 a ha) * b ↔ a_1 ≤ b) }
Instances For
Equiv.mulRight₀
as an OrderIso
on a LinearOrderedCommGroupWithZero.
.
Note that OrderIso.mulRight₀
refers to the LinearOrderedField
version.
Equations
- OrderIso.mulRight₀' ha = let src := Equiv.mulRight₀ a ha; { toEquiv := src, map_rel_iff' := (_ : ∀ {a_1 b : α}, a_1 * ↑(Units.mk0 a ha) ≤ b * ↑(Units.mk0 a ha) ↔ a_1 ≤ b) }
Instances For
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