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agdaproofs/IntegersModNRing.agda
2019-10-02 18:59:46 +01:00

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{-# OPTIONS --safe --warning=error #-}
open import LogicalFormulae
open import Orders
open import Groups.Groups
open import Numbers.Naturals.Naturals
open import Numbers.Naturals.WithK
open import Numbers.Primes.PrimeNumbers
open import Rings.Definition
open import Setoids.Setoids
open import Numbers.Modulo.IntegersModN
open import Semirings.Definition
module IntegersModNRing where
modNTo : {n : } {pr : 0 <N n} (a : n n pr)
modNTo record { x = x ; xLess = xLess } = x
*nhelper : {n : } {pr : 0 <N n} (max : ) (a : n n pr) n n pr (max modNTo a) n n pr
*nhelper {zero} {()}
*nhelper {succ n} zero a b pr2 = record { x = 0 ; xLess = succIsPositive n }
*nhelper {succ n} (succ max) record { x = zero ; xLess = xLess } b ()
*nhelper {succ n} (succ max) record { x = (succ x) ; xLess = xLess } b pr2 = (*nhelper max record { x = x ; xLess = xLess2 } b (succInjective pr2)) +n b
where
xLess2 : x <N succ n
xLess2 = PartialOrder.transitive (TotalOrder.order TotalOrder) (a<SuccA x) xLess
_*n_ : {n : } {pr : 0 <N n} n n pr n n pr n n pr
_*n_ {0} {()}
_*n_ {succ n} {_} record { x = a ; xLess = aLess } b = *nhelper a record { x = a ; xLess = aLess } b refl
nIdent : (n : ) (pr : 0 <N n) n n pr
nIdent 0 ()
nIdent 1 pr = record { x = 0 ; xLess = pr }
nIdent (succ (succ n)) _ = record { x = 1 ; xLess = succPreservesInequality (succIsPositive n) }
nMult0Right : {n : } {pr : 0 <N n} (max : ) (a : n n pr) (modNTo a max) (a *n record { x = 0 ; xLess = pr }) record { x = 0 ; xLess = pr }
nMult0Right {0} {()}
nMult0Right {succ n} .zero record { x = zero ; xLess = xLess } refl = equalityZn _ _ refl
nMult0Right {succ n} {pr} (.succ x) record { x = (succ x) ; xLess = xLess } refl rewrite nMult0Right {succ n} {pr} x record { x = x ; xLess = PartialOrder.transitive (TotalOrder.order TotalOrder) (a<SuccA x) xLess } refl = equalityZn _ _ refl
nMultCommutative : {n : } {pr : 0 <N n} (a b : n n pr) (a *n b) (b *n a)
nMultCommutative {0} {()}
nMultCommutative {succ n} {pr} record { x = zero ; xLess = xLess } b with <NRefl pr xLess
... | refl rewrite nMult0Right (modNTo b) b refl = equalityZn _ _ refl
nMultCommutative {succ n} record { x = (succ x) ; xLess = xLess } b = {!!}
nMultIdent : {n : } {pr : 0 <N n} (a : n n pr) (nIdent n pr) *n a a
nMultIdent {zero} {()}
nMultIdent {succ zero} {pr} record { x = zero ; xLess = (le diff proof) } = equalityZn _ _ refl
nMultIdent {succ zero} {pr} record { x = (succ a) ; xLess = (le diff proof) } = exFalso f
where
f : False
f rewrite Semiring.commutative Semiring diff (succ a) = naughtE (succInjective (equalityCommutative proof))
nMultIdent {succ (succ n)} {pr} record { x = a ; xLess = aLess } with orderIsTotal a (succ (succ n))
nMultIdent {succ (succ n)} {pr} record { x = a ; xLess = aLess } | inl (inl a<ssn) = equalityZn _ _ refl
nMultIdent {succ (succ n)} {pr} record { x = a ; xLess = aLess } | inl (inr ssn<a) = exFalso (PartialOrder.irreflexive (TotalOrder.order TotalOrder) (PartialOrder.transitive (TotalOrder.order TotalOrder) aLess ssn<a))
nMultIdent {succ (succ n)} {pr} record { x = .(succ (succ n)) ; xLess = aLess } | inr refl = exFalso (PartialOrder.irreflexive (TotalOrder.order TotalOrder) aLess)
nRing : (n : ) (pr : 0 <N n) Ring (reflSetoid (n n pr)) (_+n_) (_*n_)
Ring.additiveGroup (nRing n 0<n) = (nGroup n 0<n)
Ring.multWellDefined (nRing n 0<n) = reflGroupWellDefined
Ring.1R (nRing n pr) = nIdent n pr
Ring.groupIsAbelian (nRing n 0<n) = AbelianGroup.commutative (nAbGroup n 0<n)
Ring.multAssoc (nRing n 0<n) = {!!}
Ring.multCommutative (nRing n 0<n) {a} {b} = nMultCommutative a b
Ring.multDistributes (nRing n 0<n) = {!!}
Ring.multIdentIsIdent (nRing n 0<n) {a} = nMultIdent a