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

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{-# OPTIONS --safe --warning=error --without-K #-}
open import LogicalFormulae
open import Groups.Homomorphisms.Definition
open import Groups.Definition
open import Rings.Definition
open import Rings.Homomorphisms.Definition
open import Rings.IntegralDomains.Definition
open import Setoids.Setoids
open import Sets.EquivalenceRelations
module Fields.FieldOfFractions.Lemmas {a b : _} {A : Set a} {S : Setoid {a} {b} A} {_+_ : A A A} {_*_ : A A A} {R : Ring S _+_ _*_} (I : IntegralDomain R) where
open import Fields.FieldOfFractions.Setoid I
open import Fields.FieldOfFractions.Ring I
embedIntoFieldOfFractions : A fieldOfFractionsSet
embedIntoFieldOfFractions a = a ,, (Ring.1R R , IntegralDomain.nontrivial I)
homIntoFieldOfFractions : RingHom R fieldOfFractionsRing embedIntoFieldOfFractions
RingHom.preserves1 homIntoFieldOfFractions = Equivalence.reflexive (Setoid.eq S)
RingHom.ringHom homIntoFieldOfFractions {a} {b} = Equivalence.transitive (Setoid.eq S) (Ring.*WellDefined R (Equivalence.reflexive (Setoid.eq S)) (Ring.identIsIdent R)) (Ring.*Commutative R)
GroupHom.groupHom (RingHom.groupHom homIntoFieldOfFractions) {x} {y} = need
where
open Setoid S
open Equivalence eq
need : ((x + y) * (Ring.1R R * Ring.1R R)) (Ring.1R R * ((x * Ring.1R R) + (Ring.1R R * y)))
need = transitive (transitive (Ring.*WellDefined R reflexive (Ring.identIsIdent R)) (transitive (Ring.*Commutative R) (transitive (Ring.identIsIdent R) (Group.+WellDefined (Ring.additiveGroup R) (symmetric (transitive (Ring.*Commutative R) (Ring.identIsIdent R))) (symmetric (Ring.identIsIdent R)))))) (symmetric (Ring.identIsIdent R))
GroupHom.wellDefined (RingHom.groupHom homIntoFieldOfFractions) x=y = transitive (Ring.*Commutative R) (Ring.*WellDefined R reflexive x=y)
where
open Equivalence (Setoid.eq S)
homIntoFieldOfFractionsIsInj : SetoidInjection S fieldOfFractionsSetoid embedIntoFieldOfFractions
SetoidInjection.wellDefined homIntoFieldOfFractionsIsInj x=y = transitive (Ring.*Commutative R) (Ring.*WellDefined R reflexive x=y)
where
open Equivalence (Setoid.eq S)
SetoidInjection.injective homIntoFieldOfFractionsIsInj x~y = transitive (symmetric identIsIdent) (transitive *Commutative (transitive x~y identIsIdent))
where
open Ring R
open Setoid S
open Equivalence eq