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agdaproofs/Modules/Lemmas.agda
2020-01-05 15:06:35 +00:00

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{-# OPTIONS --safe --warning=error --without-K #-}
open import Groups.Definition
open import Groups.Lemmas
open import Groups.Abelian.Definition
open import Setoids.Setoids
open import Sets.EquivalenceRelations
open import Rings.Definition
open import Modules.Definition
module Modules.Lemmas {a b : _} {A : Set a} {S : Setoid {a} {b} A} {_+R_ : A A A} {_*_ : A A A} {R : Ring S _+R_ _*_} {m n : _} {M : Set m} {T : Setoid {m} {n} M} {_+_ : M M M} {G' : Group T _+_} {G : AbelianGroup G'} {_·_ : A M M} (mod : Module R G _·_) where
open Group G'
open Ring R
open Setoid T
open Equivalence eq
open Module mod
moduleTimesZero : {x : M} (0R · x) 0G
moduleTimesZero {x} = equalsDoubleImpliesZero G' (symmetric x=2x)
where
x=2x : (0R · x) (0R · x) + (0R · x)
x=2x = transitive (dotWellDefined (Equivalence.symmetric (Setoid.eq S) (Group.identLeft additiveGroup)) reflexive) dotDistributesRight
moduleTimes-1 : {x : M} ((Group.inverse additiveGroup 1R) · x) inverse x
moduleTimes-1 {x} = transitive (transferToRight' G' j) (inverseWellDefined G' dotIdentity)
where
i : ((1R · x) + ((Group.inverse additiveGroup 1R) · x)) 0G
i = transitive (symmetric (transitive (dotWellDefined (Equivalence.symmetric (Setoid.eq S) (Group.invRight additiveGroup {1R})) reflexive) dotDistributesRight)) (moduleTimesZero)
j : (((Group.inverse additiveGroup 1R) · x) + (1R · x)) 0G
j = transitive (AbelianGroup.commutative G) i