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agdaproofs/Rings/Characteristic.agda
2020-04-11 12:14:03 +01:00

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{-# OPTIONS --safe --warning=error --without-K #-}
open import LogicalFormulae
open import Groups.Abelian.Definition
open import Groups.Definition
open import Groups.Lemmas
open import Rings.Definition
open import Setoids.Setoids
open import Sets.EquivalenceRelations
open import Numbers.Naturals.Semiring
open import Numbers.Naturals.EuclideanAlgorithm
open import Numbers.Primes.PrimeNumbers
module Rings.Characteristic {a b : _} {A : Set a} {S : Setoid {a} {b} A} {_+_ : A A A} {_*_ : A A A} (R : Ring S _+_ _*_) where
open import Rings.InitialRing R
open Ring R
open Setoid S
open Equivalence eq
open Group additiveGroup
characteristicWellDefined : (0R 1R False) {n m : } Prime n Prime m fromN n 0R fromN m 0R n m
characteristicWellDefined 0!=1 {n} {m} pN pM n=0 m=0 with divisionDecidable m n
... | inl n|m = equalityCommutative (primeDivPrimeImpliesEqual pM pN n|m)
... | inr notDiv with hcfPrimeIsOne {m} {n} pM notDiv
... | bl = exFalso (0!=1 v)
where
t : (n *N extendedHcf.extended1 (euclid n m) m *N extendedHcf.extended2 (euclid n m) +N extendedHcf.c (euclid n m)) || (n *N extendedHcf.extended1 (euclid n m) +N extendedHcf.c (euclid n m) m *N extendedHcf.extended2 (euclid n m))
t = extendedHcf.extendedProof (euclid n m)
u : (n *N extendedHcf.extended1 (euclid n m) m *N extendedHcf.extended2 (euclid n m) +N 1) || (n *N extendedHcf.extended1 (euclid n m) +N 1 m *N extendedHcf.extended2 (euclid n m))
u with t
... | inl x = inl (transitivity x (applyEquality (λ i m *N extendedHcf.extended2 (euclid n m) +N i) bl))
... | inr x = inr (transitivity (applyEquality (n *N extendedHcf.extended1 (euclid n m) +N_) (equalityCommutative bl)) x)
v : 0R 1R
v with u
... | inr x = symmetric (transitive (symmetric (transitive (fromNPreserves+ (n *N extendedHcf.extended1 (euclid n m)) 1) (transitive (+WellDefined (transitive (fromNPreserves* n (extendedHcf.extended1 (euclid n m))) (transitive (*WellDefined n=0 reflexive) timesZero')) identRight) identLeft))) (transitive (fromNWellDefined x) (transitive (fromNPreserves* m (extendedHcf.extended2 (euclid n m))) (transitive (*WellDefined m=0 reflexive) timesZero'))))
... | inl x = transitive (transitive (transitive (symmetric timesZero') (transitive (*WellDefined (symmetric n=0) reflexive) (transitive (symmetric (fromNPreserves* n (extendedHcf.extended1 (euclid n m)))) (transitive (fromNWellDefined x) (transitive (fromNPreserves+ (m *N extendedHcf.extended2 (euclid n m)) 1) (+WellDefined (fromNPreserves* m (extendedHcf.extended2 (euclid n m))) reflexive)))))) (+WellDefined (transitive (*WellDefined m=0 reflexive) timesZero') (identRight))) identLeft