{-# OPTIONS --without-K --safe #-}
module Data.Rational.Unnormalised.Properties where
open import Algebra
open import Algebra.Lattice
import Algebra.Consequences.Setoid as Consequences
open import Algebra.Consequences.Propositional
open import Algebra.Construct.NaturalChoice.Base
import Algebra.Construct.NaturalChoice.MinMaxOp as MinMaxOp
import Algebra.Lattice.Construct.NaturalChoice.MinMaxOp as LatticeMinMaxOp
open import Data.Bool.Base using (T; true; false)
open import Data.Nat.Base as ℕ using (suc; pred)
import Data.Nat.Properties as ℕ
open import Data.Nat.Solver renaming (module +-*-Solver to ℕ-solver)
open import Data.Integer.Base as ℤ using (ℤ; +0; +[1+_]; -[1+_]; 0ℤ; 1ℤ; -1ℤ)
open import Data.Integer.Solver renaming (module +-*-Solver to ℤ-solver)
import Data.Integer.Properties as ℤ
open import Data.Rational.Unnormalised.Base
open import Data.Product using (_,_)
open import Data.Sum.Base using (_⊎_; [_,_]′; inj₁; inj₂)
import Data.Sign as Sign
open import Function.Base using (_on_; _$_; _∘_)
open import Level using (0ℓ)
open import Relation.Nullary using (¬_; yes; no)
import Relation.Nullary.Decidable as Dec
open import Relation.Nullary.Negation using (contradiction; contraposition)
open import Relation.Binary
import Relation.Binary.Consequences as BC
open import Relation.Binary.PropositionalEquality
import Relation.Binary.Properties.Poset as PosetProperties
open import Algebra.Properties.CommutativeSemigroup ℤ.*-commutativeSemigroup
private
variable
p q r : ℚᵘ
↥↧≡⇒≡ : ∀ {p q} → ↥ p ≡ ↥ q → ↧ₙ p ≡ ↧ₙ q → p ≡ q
↥↧≡⇒≡ {mkℚᵘ _ _} {mkℚᵘ _ _} refl refl = refl
/-cong : ∀ {n₁ d₁ n₂ d₂} .{{_ : ℕ.NonZero d₁}} .{{_ : ℕ.NonZero d₂}} →
n₁ ≡ n₂ → d₁ ≡ d₂ → n₁ / d₁ ≡ n₂ / d₂
/-cong refl refl = refl
↥[n/d]≡n : ∀ n d .{{_ : ℕ.NonZero d}} → ↥ (n / d) ≡ n
↥[n/d]≡n n (suc d) = refl
↧[n/d]≡d : ∀ n d .{{_ : ℕ.NonZero d}} → ↧ (n / d) ≡ ℤ.+ d
↧[n/d]≡d n (suc d) = refl
drop-*≡* : ∀ {p q} → p ≃ q → ↥ p ℤ.* ↧ q ≡ ↥ q ℤ.* ↧ p
drop-*≡* (*≡* eq) = eq
≃-refl : Reflexive _≃_
≃-refl = *≡* refl
≃-reflexive : _≡_ ⇒ _≃_
≃-reflexive refl = *≡* refl
≃-sym : Symmetric _≃_
≃-sym (*≡* eq) = *≡* (sym eq)
≃-trans : Transitive _≃_
≃-trans {x} {y} {z} (*≡* ad≡cb) (*≡* cf≡ed) =
*≡* (ℤ.*-cancelʳ-≡ (↥ x ℤ.* ↧ z) (↥ z ℤ.* ↧ x) (↧ y) (begin
↥ x ℤ.* ↧ z ℤ.* ↧ y ≡⟨ xy∙z≈xz∙y (↥ x) _ _ ⟩
↥ x ℤ.* ↧ y ℤ.* ↧ z ≡⟨ cong (ℤ._* ↧ z) ad≡cb ⟩
↥ y ℤ.* ↧ x ℤ.* ↧ z ≡⟨ xy∙z≈xz∙y (↥ y) _ _ ⟩
↥ y ℤ.* ↧ z ℤ.* ↧ x ≡⟨ cong (ℤ._* ↧ x) cf≡ed ⟩
↥ z ℤ.* ↧ y ℤ.* ↧ x ≡⟨ xy∙z≈xz∙y (↥ z) _ _ ⟩
↥ z ℤ.* ↧ x ℤ.* ↧ y ∎))
where open ≡-Reasoning
_≃?_ : Decidable _≃_
p ≃? q = Dec.map′ *≡* drop-*≡* (↥ p ℤ.* ↧ q ℤ.≟ ↥ q ℤ.* ↧ p)
≃-isEquivalence : IsEquivalence _≃_
≃-isEquivalence = record
{ refl = ≃-refl
; sym = ≃-sym
; trans = ≃-trans
}
≃-isDecEquivalence : IsDecEquivalence _≃_
≃-isDecEquivalence = record
{ isEquivalence = ≃-isEquivalence
; _≟_ = _≃?_
}
≃-setoid : Setoid 0ℓ 0ℓ
≃-setoid = record
{ isEquivalence = ≃-isEquivalence
}
≃-decSetoid : DecSetoid 0ℓ 0ℓ
≃-decSetoid = record
{ isDecEquivalence = ≃-isDecEquivalence
}
neg-involutive-≡ : Involutive _≡_ (-_)
neg-involutive-≡ (mkℚᵘ n d) = cong (λ n → mkℚᵘ n d) (ℤ.neg-involutive n)
neg-involutive : Involutive _≃_ (-_)
neg-involutive p rewrite neg-involutive-≡ p = ≃-refl
-‿cong : Congruent₁ _≃_ (-_)
-‿cong {p@record{}} {q@record{}} (*≡* p≡q) = *≡* (begin
↥(- p) ℤ.* ↧ q ≡˘⟨ ℤ.*-identityˡ (ℤ.- (↥ p) ℤ.* ↧ q) ⟩
1ℤ ℤ.* (↥(- p) ℤ.* ↧ q) ≡˘⟨ ℤ.*-assoc 1ℤ (↥ (- p)) (↧ q) ⟩
(1ℤ ℤ.* ℤ.-(↥ p)) ℤ.* ↧ q ≡˘⟨ cong (ℤ._* ↧ q) (ℤ.neg-distribʳ-* 1ℤ (↥ p)) ⟩
ℤ.-(1ℤ ℤ.* ↥ p) ℤ.* ↧ q ≡⟨ cong (ℤ._* ↧ q) (ℤ.neg-distribˡ-* 1ℤ (↥ p)) ⟩
(-1ℤ ℤ.* ↥ p) ℤ.* ↧ q ≡⟨ ℤ.*-assoc ℤ.-1ℤ (↥ p) (↧ q) ⟩
-1ℤ ℤ.* (↥ p ℤ.* ↧ q) ≡⟨ cong (ℤ.-1ℤ ℤ.*_) p≡q ⟩
-1ℤ ℤ.* (↥ q ℤ.* ↧ p) ≡˘⟨ ℤ.*-assoc ℤ.-1ℤ (↥ q) (↧ p) ⟩
(-1ℤ ℤ.* ↥ q) ℤ.* ↧ p ≡˘⟨ cong (ℤ._* ↧ p) (ℤ.neg-distribˡ-* 1ℤ (↥ q)) ⟩
ℤ.-(1ℤ ℤ.* ↥ q) ℤ.* ↧ p ≡⟨ cong (ℤ._* ↧ p) (ℤ.neg-distribʳ-* 1ℤ (↥ q)) ⟩
(1ℤ ℤ.* ↥(- q)) ℤ.* ↧ p ≡⟨ ℤ.*-assoc 1ℤ (ℤ.- (↥ q)) (↧ p) ⟩
1ℤ ℤ.* (↥(- q) ℤ.* ↧ p) ≡⟨ ℤ.*-identityˡ (↥ (- q) ℤ.* ↧ p) ⟩
↥(- q) ℤ.* ↧ p ∎)
where open ≡-Reasoning
neg-mono-< : -_ Preserves _<_ ⟶ _>_
neg-mono-< {p@record{}} {q@record{}} (*<* p<q) = *<* $ begin-strict
ℤ.- ↥ q ℤ.* ↧ p ≡˘⟨ ℤ.neg-distribˡ-* (↥ q) (↧ p) ⟩
ℤ.- (↥ q ℤ.* ↧ p) <⟨ ℤ.neg-mono-< p<q ⟩
ℤ.- (↥ p ℤ.* ↧ q) ≡⟨ ℤ.neg-distribˡ-* (↥ p) (↧ q) ⟩
↥ (- p) ℤ.* ↧ (- q) ∎
where open ℤ.≤-Reasoning
neg-cancel-< : ∀ {p q} → - p < - q → q < p
neg-cancel-< {p@record{}} {q@record{}} (*<* -↥p↧q<-↥q↧p) = *<* $ begin-strict
↥ q ℤ.* ↧ p ≡˘⟨ ℤ.neg-involutive (↥ q ℤ.* ↧ p) ⟩
ℤ.- ℤ.- (↥ q ℤ.* ↧ p) ≡⟨ cong ℤ.-_ (ℤ.neg-distribˡ-* (↥ q) (↧ p)) ⟩
ℤ.- ((ℤ.- ↥ q) ℤ.* ↧ p) <⟨ ℤ.neg-mono-< -↥p↧q<-↥q↧p ⟩
ℤ.- ((ℤ.- ↥ p) ℤ.* ↧ q) ≡˘⟨ cong ℤ.-_ (ℤ.neg-distribˡ-* (↥ p) (↧ q)) ⟩
ℤ.- ℤ.- (↥ p ℤ.* ↧ q) ≡⟨ ℤ.neg-involutive (↥ p ℤ.* ↧ q) ⟩
↥ p ℤ.* ↧ q ∎
where open ℤ.≤-Reasoning
drop-*≤* : p ≤ q → (↥ p ℤ.* ↧ q) ℤ.≤ (↥ q ℤ.* ↧ p)
drop-*≤* (*≤* pq≤qp) = pq≤qp
≤-reflexive : _≃_ ⇒ _≤_
≤-reflexive (*≡* eq) = *≤* (ℤ.≤-reflexive eq)
≤-refl : Reflexive _≤_
≤-refl = ≤-reflexive ≃-refl
≤-reflexive-≡ : _≡_ ⇒ _≤_
≤-reflexive-≡ refl = ≤-refl
≤-trans : Transitive _≤_
≤-trans {p} {q} {r} (*≤* eq₁) (*≤* eq₂)
= let n₁ = ↥ p; n₂ = ↥ q; n₃ = ↥ r; d₁ = ↧ p; d₂ = ↧ q; d₃ = ↧ r in *≤* $
ℤ.*-cancelʳ-≤-pos (n₁ ℤ.* d₃) (n₃ ℤ.* d₁) d₂ $ begin
(n₁ ℤ.* d₃) ℤ.* d₂ ≡⟨ ℤ.*-assoc n₁ d₃ d₂ ⟩
n₁ ℤ.* (d₃ ℤ.* d₂) ≡⟨ cong (n₁ ℤ.*_) (ℤ.*-comm d₃ d₂) ⟩
n₁ ℤ.* (d₂ ℤ.* d₃) ≡˘⟨ ℤ.*-assoc n₁ d₂ d₃ ⟩
(n₁ ℤ.* d₂) ℤ.* d₃ ≤⟨ ℤ.*-monoʳ-≤-nonNeg d₃ eq₁ ⟩
(n₂ ℤ.* d₁) ℤ.* d₃ ≡⟨ cong (ℤ._* d₃) (ℤ.*-comm n₂ d₁) ⟩
(d₁ ℤ.* n₂) ℤ.* d₃ ≡⟨ ℤ.*-assoc d₁ n₂ d₃ ⟩
d₁ ℤ.* (n₂ ℤ.* d₃) ≤⟨ ℤ.*-monoˡ-≤-nonNeg d₁ eq₂ ⟩
d₁ ℤ.* (n₃ ℤ.* d₂) ≡˘⟨ ℤ.*-assoc d₁ n₃ d₂ ⟩
(d₁ ℤ.* n₃) ℤ.* d₂ ≡⟨ cong (ℤ._* d₂) (ℤ.*-comm d₁ n₃) ⟩
(n₃ ℤ.* d₁) ℤ.* d₂ ∎ where open ℤ.≤-Reasoning
≤-antisym : Antisymmetric _≃_ _≤_
≤-antisym (*≤* le₁) (*≤* le₂) = *≡* (ℤ.≤-antisym le₁ le₂)
≤-total : Total _≤_
≤-total p q = [ inj₁ ∘ *≤* , inj₂ ∘ *≤* ]′ (ℤ.≤-total
(↥ p ℤ.* ↧ q)
(↥ q ℤ.* ↧ p))
≤-respˡ-≃ : _≤_ Respectsˡ _≃_
≤-respˡ-≃ x≈y = ≤-trans (≤-reflexive (≃-sym x≈y))
≤-respʳ-≃ : _≤_ Respectsʳ _≃_
≤-respʳ-≃ x≈y z≤x = ≤-trans z≤x (≤-reflexive x≈y)
≤-resp₂-≃ : _≤_ Respects₂ _≃_
≤-resp₂-≃ = ≤-respʳ-≃ , ≤-respˡ-≃
infix 4 _≤?_
_≤?_ : Decidable _≤_
p ≤? q = Dec.map′ *≤* drop-*≤* (↥ p ℤ.* ↧ q ℤ.≤? ↥ q ℤ.* ↧ p)
≤-irrelevant : Irrelevant _≤_
≤-irrelevant (*≤* p≤q₁) (*≤* p≤q₂) = cong *≤* (ℤ.≤-irrelevant p≤q₁ p≤q₂)
≤-isPreorder : IsPreorder _≃_ _≤_
≤-isPreorder = record
{ isEquivalence = ≃-isEquivalence
; reflexive = ≤-reflexive
; trans = ≤-trans
}
≤-isTotalPreorder : IsTotalPreorder _≃_ _≤_
≤-isTotalPreorder = record
{ isPreorder = ≤-isPreorder
; total = ≤-total
}
≤-isPartialOrder : IsPartialOrder _≃_ _≤_
≤-isPartialOrder = record
{ isPreorder = ≤-isPreorder
; antisym = ≤-antisym
}
≤-isTotalOrder : IsTotalOrder _≃_ _≤_
≤-isTotalOrder = record
{ isPartialOrder = ≤-isPartialOrder
; total = ≤-total
}
≤-isDecTotalOrder : IsDecTotalOrder _≃_ _≤_
≤-isDecTotalOrder = record
{ isTotalOrder = ≤-isTotalOrder
; _≟_ = _≃?_
; _≤?_ = _≤?_
}
≤-preorder : Preorder 0ℓ 0ℓ 0ℓ
≤-preorder = record
{ isPreorder = ≤-isPreorder
}
≤-totalPreorder : TotalPreorder 0ℓ 0ℓ 0ℓ
≤-totalPreorder = record
{ isTotalPreorder = ≤-isTotalPreorder
}
≤-poset : Poset 0ℓ 0ℓ 0ℓ
≤-poset = record
{ isPartialOrder = ≤-isPartialOrder
}
≤-totalOrder : TotalOrder 0ℓ 0ℓ 0ℓ
≤-totalOrder = record
{ isTotalOrder = ≤-isTotalOrder
}
≤-decTotalOrder : DecTotalOrder 0ℓ 0ℓ 0ℓ
≤-decTotalOrder = record
{ isDecTotalOrder = ≤-isDecTotalOrder
}
≤-isPreorder-≡ : IsPreorder _≡_ _≤_
≤-isPreorder-≡ = record
{ isEquivalence = isEquivalence
; reflexive = ≤-reflexive-≡
; trans = ≤-trans
}
≤-isTotalPreorder-≡ : IsTotalPreorder _≡_ _≤_
≤-isTotalPreorder-≡ = record
{ isPreorder = ≤-isPreorder-≡
; total = ≤-total
}
≤-preorder-≡ : Preorder 0ℓ 0ℓ 0ℓ
≤-preorder-≡ = record
{ isPreorder = ≤-isPreorder-≡
}
≤-totalPreorder-≡ : TotalPreorder 0ℓ 0ℓ 0ℓ
≤-totalPreorder-≡ = record
{ isTotalPreorder = ≤-isTotalPreorder-≡
}
mono⇒cong : ∀ {f} → f Preserves _≤_ ⟶ _≤_ → f Preserves _≃_ ⟶ _≃_
mono⇒cong = BC.mono⇒cong _≃_ _≃_ ≃-sym ≤-reflexive ≤-antisym
antimono⇒cong : ∀ {f} → f Preserves _≤_ ⟶ _≥_ → f Preserves _≃_ ⟶ _≃_
antimono⇒cong = BC.antimono⇒cong _≃_ _≃_ ≃-sym ≤-reflexive ≤-antisym
≤ᵇ⇒≤ : T (p ≤ᵇ q) → p ≤ q
≤ᵇ⇒≤ = *≤* ∘ ℤ.≤ᵇ⇒≤
≤⇒≤ᵇ : p ≤ q → T (p ≤ᵇ q)
≤⇒≤ᵇ = ℤ.≤⇒≤ᵇ ∘ drop-*≤*
drop-*<* : p < q → (↥ p ℤ.* ↧ q) ℤ.< (↥ q ℤ.* ↧ p)
drop-*<* (*<* pq<qp) = pq<qp
<⇒≤ : _<_ ⇒ _≤_
<⇒≤ (*<* p<q) = *≤* (ℤ.<⇒≤ p<q)
<⇒≢ : _<_ ⇒ _≢_
<⇒≢ (*<* x<y) refl = ℤ.<⇒≢ x<y refl
<⇒≱ : _<_ ⇒ _≱_
<⇒≱ (*<* x<y) = ℤ.<⇒≱ x<y ∘ drop-*≤*
≰⇒> : _≰_ ⇒ _>_
≰⇒> p≰q = *<* (ℤ.≰⇒> (p≰q ∘ *≤*))
≮⇒≥ : _≮_ ⇒ _≥_
≮⇒≥ p≮q = *≤* (ℤ.≮⇒≥ (p≮q ∘ *<*))
≰⇒≥ : _≰_ ⇒ _≥_
≰⇒≥ = <⇒≤ ∘ ≰⇒>
<-irrefl-≡ : Irreflexive _≡_ _<_
<-irrefl-≡ refl (*<* x<x) = ℤ.<-irrefl refl x<x
<-irrefl : Irreflexive _≃_ _<_
<-irrefl (*≡* x≡y) (*<* x<y) = ℤ.<-irrefl x≡y x<y
<-asym : Asymmetric _<_
<-asym (*<* x<y) = ℤ.<-asym x<y ∘ drop-*<*
≤-<-trans : Trans _≤_ _<_ _<_
≤-<-trans {p} {q} {r} (*≤* p≤q) (*<* q<r) = *<* $
ℤ.*-cancelʳ-<-nonNeg _ $ begin-strict
n₁ ℤ.* d₃ ℤ.* d₂ ≡⟨ ℤ.*-assoc n₁ d₃ d₂ ⟩
n₁ ℤ.* (d₃ ℤ.* d₂) ≡⟨ cong (n₁ ℤ.*_) (ℤ.*-comm d₃ d₂) ⟩
n₁ ℤ.* (d₂ ℤ.* d₃) ≡˘⟨ ℤ.*-assoc n₁ d₂ d₃ ⟩
n₁ ℤ.* d₂ ℤ.* d₃ ≤⟨ ℤ.*-monoʳ-≤-nonNeg (↧ r) p≤q ⟩
n₂ ℤ.* d₁ ℤ.* d₃ ≡⟨ cong (ℤ._* d₃) (ℤ.*-comm n₂ d₁) ⟩
d₁ ℤ.* n₂ ℤ.* d₃ ≡⟨ ℤ.*-assoc d₁ n₂ d₃ ⟩
d₁ ℤ.* (n₂ ℤ.* d₃) <⟨ ℤ.*-monoˡ-<-pos (↧ p) q<r ⟩
d₁ ℤ.* (n₃ ℤ.* d₂) ≡˘⟨ ℤ.*-assoc d₁ n₃ d₂ ⟩
d₁ ℤ.* n₃ ℤ.* d₂ ≡⟨ cong (ℤ._* d₂) (ℤ.*-comm d₁ n₃) ⟩
n₃ ℤ.* d₁ ℤ.* d₂ ∎
where open ℤ.≤-Reasoning
n₁ = ↥ p; n₂ = ↥ q; n₃ = ↥ r; d₁ = ↧ p; d₂ = ↧ q; d₃ = ↧ r
<-≤-trans : Trans _<_ _≤_ _<_
<-≤-trans {p} {q} {r} (*<* p<q) (*≤* q≤r) = *<* $
ℤ.*-cancelʳ-<-nonNeg _ $ begin-strict
n₁ ℤ.* d₃ ℤ.* d₂ ≡⟨ ℤ.*-assoc n₁ d₃ d₂ ⟩
n₁ ℤ.* (d₃ ℤ.* d₂) ≡⟨ cong (n₁ ℤ.*_) (ℤ.*-comm d₃ d₂) ⟩
n₁ ℤ.* (d₂ ℤ.* d₃) ≡˘⟨ ℤ.*-assoc n₁ d₂ d₃ ⟩
n₁ ℤ.* d₂ ℤ.* d₃ <⟨ ℤ.*-monoʳ-<-pos (↧ r) p<q ⟩
n₂ ℤ.* d₁ ℤ.* d₃ ≡⟨ cong (ℤ._* d₃) (ℤ.*-comm n₂ d₁) ⟩
d₁ ℤ.* n₂ ℤ.* d₃ ≡⟨ ℤ.*-assoc d₁ n₂ d₃ ⟩
d₁ ℤ.* (n₂ ℤ.* d₃) ≤⟨ ℤ.*-monoˡ-≤-nonNeg (↧ p) q≤r ⟩
d₁ ℤ.* (n₃ ℤ.* d₂) ≡˘⟨ ℤ.*-assoc d₁ n₃ d₂ ⟩
d₁ ℤ.* n₃ ℤ.* d₂ ≡⟨ cong (ℤ._* d₂) (ℤ.*-comm d₁ n₃) ⟩
n₃ ℤ.* d₁ ℤ.* d₂ ∎
where open ℤ.≤-Reasoning
n₁ = ↥ p; n₂ = ↥ q; n₃ = ↥ r; d₁ = ↧ p; d₂ = ↧ q; d₃ = ↧ r
<-trans : Transitive _<_
<-trans = ≤-<-trans ∘ <⇒≤
<-cmp : Trichotomous _≃_ _<_
<-cmp p q with ℤ.<-cmp (↥ p ℤ.* ↧ q) (↥ q ℤ.* ↧ p)
... | tri< x<y x≉y x≯y = tri< (*<* x<y) (x≉y ∘ drop-*≡*) (x≯y ∘ drop-*<*)
... | tri≈ x≮y x≈y x≯y = tri≈ (x≮y ∘ drop-*<*) (*≡* x≈y) (x≯y ∘ drop-*<*)
... | tri> x≮y x≉y x>y = tri> (x≮y ∘ drop-*<*) (x≉y ∘ drop-*≡*) (*<* x>y)
infix 4 _<?_
_<?_ : Decidable _<_
p <? q = Dec.map′ *<* drop-*<* (↥ p ℤ.* ↧ q ℤ.<? ↥ q ℤ.* ↧ p)
<-irrelevant : Irrelevant _<_
<-irrelevant (*<* p<q₁) (*<* p<q₂) = cong *<* (ℤ.<-irrelevant p<q₁ p<q₂)
<-respʳ-≃ : _<_ Respectsʳ _≃_
<-respʳ-≃ {p} {q} {r} (*≡* q≡r) (*<* p<q) = *<* $
ℤ.*-cancelʳ-<-nonNeg _ $ begin-strict
n₁ ℤ.* d₃ ℤ.* d₂ ≡⟨ ℤ.*-assoc n₁ d₃ d₂ ⟩
n₁ ℤ.* (d₃ ℤ.* d₂) ≡⟨ cong (n₁ ℤ.*_) (ℤ.*-comm d₃ d₂) ⟩
n₁ ℤ.* (d₂ ℤ.* d₃) ≡˘⟨ ℤ.*-assoc n₁ d₂ d₃ ⟩
n₁ ℤ.* d₂ ℤ.* d₃ <⟨ ℤ.*-monoʳ-<-pos (↧ r) p<q ⟩
n₂ ℤ.* d₁ ℤ.* d₃ ≡⟨ ℤ.*-assoc n₂ d₁ d₃ ⟩
n₂ ℤ.* (d₁ ℤ.* d₃) ≡⟨ cong (n₂ ℤ.*_) (ℤ.*-comm d₁ d₃) ⟩
n₂ ℤ.* (d₃ ℤ.* d₁) ≡˘⟨ ℤ.*-assoc n₂ d₃ d₁ ⟩
n₂ ℤ.* d₃ ℤ.* d₁ ≡⟨ cong (ℤ._* d₁) q≡r ⟩
n₃ ℤ.* d₂ ℤ.* d₁ ≡⟨ ℤ.*-assoc n₃ d₂ d₁ ⟩
n₃ ℤ.* (d₂ ℤ.* d₁) ≡⟨ cong (n₃ ℤ.*_) (ℤ.*-comm d₂ d₁) ⟩
n₃ ℤ.* (d₁ ℤ.* d₂) ≡˘⟨ ℤ.*-assoc n₃ d₁ d₂ ⟩
n₃ ℤ.* d₁ ℤ.* d₂ ∎
where open ℤ.≤-Reasoning
n₁ = ↥ p; n₂ = ↥ q; n₃ = ↥ r; d₁ = ↧ p; d₂ = ↧ q; d₃ = ↧ r
<-respˡ-≃ : _<_ Respectsˡ _≃_
<-respˡ-≃ q≃r q<p
= subst (_< _) (neg-involutive-≡ _)
$ subst (_ <_) (neg-involutive-≡ _)
$ neg-mono-< (<-respʳ-≃ (-‿cong q≃r) (neg-mono-< q<p))
<-resp-≃ : _<_ Respects₂ _≃_
<-resp-≃ = <-respʳ-≃ , <-respˡ-≃
<-isStrictPartialOrder-≡ : IsStrictPartialOrder _≡_ _<_
<-isStrictPartialOrder-≡ = record
{ isEquivalence = isEquivalence
; irrefl = <-irrefl-≡
; trans = <-trans
; <-resp-≈ = subst (_ <_) , subst (_< _)
}
<-isStrictPartialOrder : IsStrictPartialOrder _≃_ _<_
<-isStrictPartialOrder = record
{ isEquivalence = ≃-isEquivalence
; irrefl = <-irrefl
; trans = <-trans
; <-resp-≈ = <-resp-≃
}
<-isStrictTotalOrder : IsStrictTotalOrder _≃_ _<_
<-isStrictTotalOrder = record
{ isEquivalence = ≃-isEquivalence
; trans = <-trans
; compare = <-cmp
}
<-strictPartialOrder-≡ : StrictPartialOrder 0ℓ 0ℓ 0ℓ
<-strictPartialOrder-≡ = record
{ isStrictPartialOrder = <-isStrictPartialOrder-≡
}
<-strictPartialOrder : StrictPartialOrder 0ℓ 0ℓ 0ℓ
<-strictPartialOrder = record
{ isStrictPartialOrder = <-isStrictPartialOrder
}
<-strictTotalOrder : StrictTotalOrder 0ℓ 0ℓ 0ℓ
<-strictTotalOrder = record
{ isStrictTotalOrder = <-isStrictTotalOrder
}
module ≤-Reasoning where
open import Relation.Binary.Reasoning.Base.Triple
≤-isPreorder
<-trans
<-resp-≃
<⇒≤
<-≤-trans
≤-<-trans
public
≥0⇒↥≥0 : ∀ {n dm} → mkℚᵘ n dm ≥ 0ℚᵘ → n ℤ.≥ 0ℤ
≥0⇒↥≥0 {n} {dm} r≥0 = ℤ.≤-trans (drop-*≤* r≥0)
(ℤ.≤-reflexive $ ℤ.*-identityʳ n)
>0⇒↥>0 : ∀ {n dm} → mkℚᵘ n dm > 0ℚᵘ → n ℤ.> 0ℤ
>0⇒↥>0 {n} {dm} r>0 = ℤ.<-≤-trans (drop-*<* r>0)
(ℤ.≤-reflexive $ ℤ.*-identityʳ n)
positive⁻¹ : ∀ p → .{{Positive p}} → p > 0ℚᵘ
positive⁻¹ (mkℚᵘ +[1+ n ] _) = *<* (ℤ.+<+ ℕ.z<s)
nonNegative⁻¹ : ∀ p → .{{NonNegative p}} → p ≥ 0ℚᵘ
nonNegative⁻¹ (mkℚᵘ +0 _) = *≤* (ℤ.+≤+ ℕ.z≤n)
nonNegative⁻¹ (mkℚᵘ +[1+ n ] _) = *≤* (ℤ.+≤+ ℕ.z≤n)
negative⁻¹ : ∀ p → .{{Negative p}} → p < 0ℚᵘ
negative⁻¹ (mkℚᵘ -[1+ n ] _) = *<* ℤ.-<+
nonPositive⁻¹ : ∀ p → .{{NonPositive p}} → p ≤ 0ℚᵘ
nonPositive⁻¹ (mkℚᵘ +0 _) = *≤* (ℤ.+≤+ ℕ.z≤n)
nonPositive⁻¹ (mkℚᵘ -[1+ n ] _) = *≤* ℤ.-≤+
pos⇒nonNeg : ∀ p → .{{Positive p}} → NonNegative p
pos⇒nonNeg (mkℚᵘ +0 _) = _
pos⇒nonNeg (mkℚᵘ +[1+ n ] _) = _
neg⇒nonPos : ∀ p → .{{Negative p}} → NonPositive p
neg⇒nonPos (mkℚᵘ +0 _) = _
neg⇒nonPos (mkℚᵘ -[1+ n ] _) = _
neg<pos : ∀ p q → .{{Negative p}} → .{{Positive q}} → p < q
neg<pos p q = <-trans (negative⁻¹ p) (positive⁻¹ q)
pos⇒nonZero : ∀ p → .{{Positive p}} → NonZero p
pos⇒nonZero (mkℚᵘ (+[1+ _ ]) _) = _
nonNeg∧nonPos⇒0 : ∀ p → .{{NonNegative p}} → .{{NonPositive p}} → p ≃ 0ℚᵘ
nonNeg∧nonPos⇒0 (mkℚᵘ +0 _) = *≡* refl
nonNeg<⇒pos : ∀ {p q} .{{_ : NonNegative p}} → p < q → Positive q
nonNeg<⇒pos {p} p<q = positive (≤-<-trans (nonNegative⁻¹ p) p<q)
nonNeg≤⇒nonNeg : ∀ {p q} .{{_ : NonNegative p}} → p ≤ q → NonNegative q
nonNeg≤⇒nonNeg {p} p≤q = nonNegative (≤-trans (nonNegative⁻¹ p) p≤q)
neg⇒nonZero : ∀ p → .{{Negative p}} → NonZero p
neg⇒nonZero (mkℚᵘ (-[1+ _ ]) _) = _
+-rawMagma : RawMagma 0ℓ 0ℓ
+-rawMagma = record
{ _≈_ = _≃_
; _∙_ = _+_
}
+-rawMonoid : RawMonoid 0ℓ 0ℓ
+-rawMonoid = record
{ _≈_ = _≃_
; _∙_ = _+_
; ε = 0ℚᵘ
}
+-0-rawGroup : RawGroup 0ℓ 0ℓ
+-0-rawGroup = record
{ Carrier = ℚᵘ
; _≈_ = _≃_
; _∙_ = _+_
; ε = 0ℚᵘ
; _⁻¹ = -_
}
+-*-rawNearSemiring : RawNearSemiring 0ℓ 0ℓ
+-*-rawNearSemiring = record
{ Carrier = ℚᵘ
; _≈_ = _≃_
; _+_ = _+_
; _*_ = _*_
; 0# = 0ℚᵘ
}
+-*-rawSemiring : RawSemiring 0ℓ 0ℓ
+-*-rawSemiring = record
{ Carrier = ℚᵘ
; _≈_ = _≃_
; _+_ = _+_
; _*_ = _*_
; 0# = 0ℚᵘ
; 1# = 1ℚᵘ
}
+-*-rawRing : RawRing 0ℓ 0ℓ
+-*-rawRing = record
{ Carrier = ℚᵘ
; _≈_ = _≃_
; _+_ = _+_
; _*_ = _*_
; -_ = -_
; 0# = 0ℚᵘ
; 1# = 1ℚᵘ
}
+-cong : Congruent₂ _≃_ _+_
+-cong {x@record{}} {y@record{}} {u@record{}} {v@record{}} (*≡* ab′∼a′b) (*≡* cd′∼c′d) = *≡* (begin
(↥x ℤ.* ↧u ℤ.+ ↥u ℤ.* ↧x) ℤ.* (↧y ℤ.* ↧v) ≡⟨ solve 6 (λ ↥x ↧x ↧y ↥u ↧u ↧v →
(↥x :* ↧u :+ ↥u :* ↧x) :* (↧y :* ↧v) :=
(↥x :* ↧y :* (↧u :* ↧v)) :+ ↥u :* ↧v :* (↧x :* ↧y))
refl (↥ x) (↧ x) (↧ y) (↥ u) (↧ u) (↧ v) ⟩
↥x ℤ.* ↧y ℤ.* (↧u ℤ.* ↧v) ℤ.+ ↥u ℤ.* ↧v ℤ.* (↧x ℤ.* ↧y) ≡⟨ cong₂ ℤ._+_ (cong (ℤ._* (↧u ℤ.* ↧v)) ab′∼a′b)
(cong (ℤ._* (↧x ℤ.* ↧y)) cd′∼c′d) ⟩
↥y ℤ.* ↧x ℤ.* (↧u ℤ.* ↧v) ℤ.+ ↥v ℤ.* ↧u ℤ.* (↧x ℤ.* ↧y) ≡⟨ solve 6 (λ ↧x ↥y ↧y ↧u ↥v ↧v →
(↥y :* ↧x :* (↧u :* ↧v)) :+ ↥v :* ↧u :* (↧x :* ↧y) :=
(↥y :* ↧v :+ ↥v :* ↧y) :* (↧x :* ↧u))
refl (↧ x) (↥ y) (↧ y) (↧ u) (↥ v) (↧ v) ⟩
(↥y ℤ.* ↧v ℤ.+ ↥v ℤ.* ↧y) ℤ.* (↧x ℤ.* ↧u) ∎)
where
↥x = ↥ x; ↧x = ↧ x; ↥y = ↥ y; ↧y = ↧ y; ↥u = ↥ u; ↧u = ↧ u; ↥v = ↥ v; ↧v = ↧ v
open ≡-Reasoning
open ℤ-solver
+-congʳ : ∀ p → q ≃ r → p + q ≃ p + r
+-congʳ p q≃r = +-cong (≃-refl {p}) q≃r
+-congˡ : ∀ p → q ≃ r → q + p ≃ r + p
+-congˡ p q≃r = +-cong q≃r (≃-refl {p})
+-assoc-↥ : Associative (_≡_ on ↥_) _+_
+-assoc-↥ p@record{} q@record{} r@record{} = solve 6 (λ ↥p ↧p ↥q ↧q ↥r ↧r →
(↥p :* ↧q :+ ↥q :* ↧p) :* ↧r :+ ↥r :* (↧p :* ↧q) :=
↥p :* (↧q :* ↧r) :+ (↥q :* ↧r :+ ↥r :* ↧q) :* ↧p)
refl (↥ p) (↧ p) (↥ q) (↧ q) (↥ r) (↧ r)
where open ℤ-solver
+-assoc-↧ : Associative (_≡_ on ↧ₙ_) _+_
+-assoc-↧ p@record{} q@record{} r@record{} = ℕ.*-assoc (↧ₙ p) (↧ₙ q) (↧ₙ r)
+-assoc-≡ : Associative _≡_ _+_
+-assoc-≡ p q r = ↥↧≡⇒≡ (+-assoc-↥ p q r) (+-assoc-↧ p q r)
+-assoc : Associative _≃_ _+_
+-assoc p q r = ≃-reflexive (+-assoc-≡ p q r)
+-comm-↥ : Commutative (_≡_ on ↥_) _+_
+-comm-↥ p@record{} q@record{} = ℤ.+-comm (↥ p ℤ.* ↧ q) (↥ q ℤ.* ↧ p)
+-comm-↧ : Commutative (_≡_ on ↧ₙ_) _+_
+-comm-↧ p@record{} q@record{} = ℕ.*-comm (↧ₙ p) (↧ₙ q)
+-comm-≡ : Commutative _≡_ _+_
+-comm-≡ p q = ↥↧≡⇒≡ (+-comm-↥ p q) (+-comm-↧ p q)
+-comm : Commutative _≃_ _+_
+-comm p q = ≃-reflexive (+-comm-≡ p q)
+-identityˡ-↥ : LeftIdentity (_≡_ on ↥_) 0ℚᵘ _+_
+-identityˡ-↥ p@record{} = begin
0ℤ ℤ.* ↧ p ℤ.+ ↥ p ℤ.* 1ℤ ≡⟨ cong₂ ℤ._+_ (ℤ.*-zeroˡ (↧ p)) (ℤ.*-identityʳ (↥ p)) ⟩
0ℤ ℤ.+ ↥ p ≡⟨ ℤ.+-identityˡ (↥ p) ⟩
↥ p ∎ where open ≡-Reasoning
+-identityˡ-↧ : LeftIdentity (_≡_ on ↧ₙ_) 0ℚᵘ _+_
+-identityˡ-↧ p@record{} = ℕ.+-identityʳ (↧ₙ p)
+-identityˡ-≡ : LeftIdentity _≡_ 0ℚᵘ _+_
+-identityˡ-≡ p = ↥↧≡⇒≡ (+-identityˡ-↥ p) (+-identityˡ-↧ p)
+-identityˡ : LeftIdentity _≃_ 0ℚᵘ _+_
+-identityˡ p = ≃-reflexive (+-identityˡ-≡ p)
+-identityʳ-≡ : RightIdentity _≡_ 0ℚᵘ _+_
+-identityʳ-≡ = comm+idˡ⇒idʳ +-comm-≡ {e = 0ℚᵘ} +-identityˡ-≡
+-identityʳ : RightIdentity _≃_ 0ℚᵘ _+_
+-identityʳ p = ≃-reflexive (+-identityʳ-≡ p)
+-identity-≡ : Identity _≡_ 0ℚᵘ _+_
+-identity-≡ = +-identityˡ-≡ , +-identityʳ-≡
+-identity : Identity _≃_ 0ℚᵘ _+_
+-identity = +-identityˡ , +-identityʳ
+-inverseˡ : LeftInverse _≃_ 0ℚᵘ -_ _+_
+-inverseˡ p@record{} = *≡* let n = ↥ p; d = ↧ p in
((ℤ.- n) ℤ.* d ℤ.+ n ℤ.* d) ℤ.* 1ℤ ≡⟨ ℤ.*-identityʳ ((ℤ.- n) ℤ.* d ℤ.+ n ℤ.* d) ⟩
(ℤ.- n) ℤ.* d ℤ.+ n ℤ.* d ≡˘⟨ cong (ℤ._+ (n ℤ.* d)) (ℤ.neg-distribˡ-* n d) ⟩
ℤ.- (n ℤ.* d) ℤ.+ n ℤ.* d ≡⟨ ℤ.+-inverseˡ (n ℤ.* d) ⟩
0ℤ ∎ where open ≡-Reasoning
+-inverseʳ : RightInverse _≃_ 0ℚᵘ -_ _+_
+-inverseʳ p@record{} = *≡* let n = ↥ p; d = ↧ p in
(n ℤ.* d ℤ.+ (ℤ.- n) ℤ.* d) ℤ.* 1ℤ ≡⟨ ℤ.*-identityʳ (n ℤ.* d ℤ.+ (ℤ.- n) ℤ.* d) ⟩
n ℤ.* d ℤ.+ (ℤ.- n) ℤ.* d ≡˘⟨ cong (λ n+d → n ℤ.* d ℤ.+ n+d) (ℤ.neg-distribˡ-* n d) ⟩
n ℤ.* d ℤ.+ ℤ.- (n ℤ.* d) ≡⟨ ℤ.+-inverseʳ (n ℤ.* d) ⟩
0ℤ ∎ where open ≡-Reasoning
+-inverse : Inverse _≃_ 0ℚᵘ -_ _+_
+-inverse = +-inverseˡ , +-inverseʳ
+-cancelˡ : ∀ {r p q} → r + p ≃ r + q → p ≃ q
+-cancelˡ {r} {p} {q} r+p≃r+q = begin-equality
p ≈˘⟨ +-identityʳ p ⟩
p + 0ℚᵘ ≈˘⟨ +-congʳ p (+-inverseʳ r) ⟩
p + (r - r) ≈˘⟨ +-assoc p r (- r) ⟩
(p + r) - r ≈⟨ +-congˡ (- r) (+-comm p r) ⟩
(r + p) - r ≈⟨ +-congˡ (- r) r+p≃r+q ⟩
(r + q) - r ≈⟨ +-congˡ (- r) (+-comm r q) ⟩
(q + r) - r ≈⟨ +-assoc q r (- r) ⟩
q + (r - r) ≈⟨ +-congʳ q (+-inverseʳ r) ⟩
q + 0ℚᵘ ≈⟨ +-identityʳ q ⟩
q ∎ where open ≤-Reasoning
+-cancelʳ : ∀ {r p q} → p + r ≃ q + r → p ≃ q
+-cancelʳ {r} {p} {q} p+r≃q+r = +-cancelˡ {r} $ begin-equality
r + p ≈⟨ +-comm r p ⟩
p + r ≈⟨ p+r≃q+r ⟩
q + r ≈⟨ +-comm q r ⟩
r + q ∎ where open ≤-Reasoning
p+p≃0⇒p≃0 : ∀ p → p + p ≃ 0ℚᵘ → p ≃ 0ℚᵘ
p+p≃0⇒p≃0 (mkℚᵘ ℤ.+0 _) (*≡* _) = *≡* refl
neg-distrib-+ : ∀ p q → - (p + q) ≡ (- p) + (- q)
neg-distrib-+ p@record{} q@record{} = ↥↧≡⇒≡ (begin
ℤ.- (↥ p ℤ.* ↧ q ℤ.+ ↥ q ℤ.* ↧ p) ≡⟨ ℤ.neg-distrib-+ (↥ p ℤ.* ↧ q) _ ⟩
ℤ.- (↥ p ℤ.* ↧ q) ℤ.+ ℤ.- (↥ q ℤ.* ↧ p) ≡⟨ cong₂ ℤ._+_ (ℤ.neg-distribˡ-* (↥ p) _)
(ℤ.neg-distribˡ-* (↥ q) _) ⟩
(ℤ.- ↥ p) ℤ.* ↧ q ℤ.+ (ℤ.- ↥ q) ℤ.* ↧ p ∎
) refl
where open ≡-Reasoning
p≃-p⇒p≃0 : ∀ p → p ≃ - p → p ≃ 0ℚᵘ
p≃-p⇒p≃0 p p≃-p = p+p≃0⇒p≃0 p (begin-equality
p + p ≈⟨ +-congʳ p p≃-p ⟩
p - p ≈⟨ +-inverseʳ p ⟩
0ℚᵘ ∎)
where open ≤-Reasoning
private
lemma : ∀ r p q → (↥ r ℤ.* ↧ p ℤ.+ ↥ p ℤ.* ↧ r) ℤ.* (↧ r ℤ.* ↧ q)
≡ (↥ r ℤ.* ↧ r) ℤ.* (↧ p ℤ.* ↧ q) ℤ.+ (↧ r ℤ.* ↧ r) ℤ.* (↥ p ℤ.* ↧ q)
lemma r p q = solve 5 (λ ↥r ↧r ↧p ↥p ↧q →
(↥r :* ↧p :+ ↥p :* ↧r) :* (↧r :* ↧q) :=
(↥r :* ↧r) :* (↧p :* ↧q) :+ (↧r :* ↧r) :* (↥p :* ↧q))
refl (↥ r) (↧ r) (↧ p) (↥ p) (↧ q)
where open ℤ-solver
+-monoʳ-≤ : ∀ r → (r +_) Preserves _≤_ ⟶ _≤_
+-monoʳ-≤ r@record{} {p@record{}} {q@record{}} (*≤* x≤y) = *≤* $ begin
↥ (r + p) ℤ.* ↧ (r + q) ≡⟨ lemma r p q ⟩
r₂ ℤ.* (↧ p ℤ.* ↧ q) ℤ.+ (↧ r ℤ.* ↧ r) ℤ.* (↥ p ℤ.* ↧ q) ≤⟨ leq ⟩
r₂ ℤ.* (↧ q ℤ.* ↧ p) ℤ.+ (↧ r ℤ.* ↧ r) ℤ.* (↥ q ℤ.* ↧ p) ≡⟨ sym $ lemma r q p ⟩
↥ (r + q) ℤ.* (↧ (r + p)) ∎
where
open ℤ.≤-Reasoning; r₂ = ↥ r ℤ.* ↧ r
leq = ℤ.+-mono-≤
(ℤ.≤-reflexive $ cong (r₂ ℤ.*_) (ℤ.*-comm (↧ p) (↧ q)))
(ℤ.*-monoˡ-≤-nonNeg (↧ r ℤ.* ↧ r) x≤y)
+-monoˡ-≤ : ∀ r → (_+ r) Preserves _≤_ ⟶ _≤_
+-monoˡ-≤ r {p} {q} rewrite +-comm-≡ p r | +-comm-≡ q r = +-monoʳ-≤ r
+-mono-≤ : _+_ Preserves₂ _≤_ ⟶ _≤_ ⟶ _≤_
+-mono-≤ {p} {q} {u} {v} p≤q u≤v = ≤-trans (+-monoˡ-≤ u p≤q) (+-monoʳ-≤ q u≤v)
≤-steps : ∀ r .{{_ : NonNegative r}} → p ≤ q → p ≤ r + q
≤-steps {p} {q} r p≤q = subst (_≤ r + q) (+-identityˡ-≡ p) (+-mono-≤ (nonNegative⁻¹ r) p≤q)
p≤q+p : ∀ p q .{{_ : NonNegative q}} → p ≤ q + p
p≤q+p p q = ≤-steps q ≤-refl
p≤p+q : ∀ p q .{{_ : NonNegative q}} → p ≤ p + q
p≤p+q p q rewrite +-comm-≡ p q = p≤q+p p q
+-monoʳ-< : ∀ r → (r +_) Preserves _<_ ⟶ _<_
+-monoʳ-< r@record{} {p@record{}} {q@record{}} (*<* x<y) = *<* $ begin-strict
↥ (r + p) ℤ.* (↧ (r + q)) ≡⟨ lemma r p q ⟩
↥r↧r ℤ.* (↧ p ℤ.* ↧ q) ℤ.+ ↧r↧r ℤ.* (↥ p ℤ.* ↧ q) <⟨ leq ⟩
↥r↧r ℤ.* (↧ q ℤ.* ↧ p) ℤ.+ ↧r↧r ℤ.* (↥ q ℤ.* ↧ p) ≡⟨ sym $ lemma r q p ⟩
↥ (r + q) ℤ.* (↧ (r + p)) ∎
where
open ℤ.≤-Reasoning; ↥r↧r = ↥ r ℤ.* ↧ r; ↧r↧r = ↧ r ℤ.* ↧ r
leq = ℤ.+-mono-≤-<
(ℤ.≤-reflexive $ cong (↥r↧r ℤ.*_) (ℤ.*-comm (↧ p) (↧ q)))
(ℤ.*-monoˡ-<-pos ↧r↧r x<y)
+-monoˡ-< : ∀ r → (_+ r) Preserves _<_ ⟶ _<_
+-monoˡ-< r {p} {q} rewrite +-comm-≡ p r | +-comm-≡ q r = +-monoʳ-< r
+-mono-< : _+_ Preserves₂ _<_ ⟶ _<_ ⟶ _<_
+-mono-< {p} {q} {u} {v} p<q u<v = <-trans (+-monoˡ-< u p<q) (+-monoʳ-< q u<v)
+-mono-≤-< : _+_ Preserves₂ _≤_ ⟶ _<_ ⟶ _<_
+-mono-≤-< {p} {q} {r} p≤q q<r = ≤-<-trans (+-monoˡ-≤ r p≤q) (+-monoʳ-< q q<r)
+-mono-<-≤ : _+_ Preserves₂ _<_ ⟶ _≤_ ⟶ _<_
+-mono-<-≤ {p} {q} {r} p<q q≤r = <-≤-trans (+-monoˡ-< r p<q) (+-monoʳ-≤ q q≤r)
pos+pos⇒pos : ∀ p .{{_ : Positive p}} →
∀ q .{{_ : Positive q}} →
Positive (p + q)
pos+pos⇒pos p q = positive (+-mono-< (positive⁻¹ p) (positive⁻¹ q))
nonNeg+nonNeg⇒nonNeg : ∀ p .{{_ : NonNegative p}} →
∀ q .{{_ : NonNegative q}} →
NonNegative (p + q)
nonNeg+nonNeg⇒nonNeg p q = nonNegative
(+-mono-≤ (nonNegative⁻¹ p) (nonNegative⁻¹ q))
+-minus-telescope : ∀ p q r → (p - q) + (q - r) ≃ p - r
+-minus-telescope p q r = begin-equality
(p - q) + (q - r) ≈⟨ ≃-sym (+-assoc (p - q) q (- r)) ⟩
(p - q) + q - r ≈⟨ +-congˡ (- r) (+-assoc p (- q) q) ⟩
(p + (- q + q)) - r ≈⟨ +-congˡ (- r) (+-congʳ p (+-inverseˡ q)) ⟩
(p + 0ℚᵘ) - r ≈⟨ +-congˡ (- r) (+-identityʳ p) ⟩
p - r ∎ where open ≤-Reasoning
p≃q⇒p-q≃0 : ∀ p q → p ≃ q → p - q ≃ 0ℚᵘ
p≃q⇒p-q≃0 p q p≃q = begin-equality
p - q ≈⟨ +-congˡ (- q) p≃q ⟩
q - q ≈⟨ +-inverseʳ q ⟩
0ℚᵘ ∎ where open ≤-Reasoning
p-q≃0⇒p≃q : ∀ p q → p - q ≃ 0ℚᵘ → p ≃ q
p-q≃0⇒p≃q p q p-q≃0 = begin-equality
p ≡˘⟨ +-identityʳ-≡ p ⟩
p + 0ℚᵘ ≈⟨ +-congʳ p (≃-sym (+-inverseˡ q)) ⟩
p + (- q + q) ≡˘⟨ +-assoc-≡ p (- q) q ⟩
(p - q) + q ≈⟨ +-congˡ q p-q≃0 ⟩
0ℚᵘ + q ≡⟨ +-identityˡ-≡ q ⟩
q ∎ where open ≤-Reasoning
neg-mono-≤ : -_ Preserves _≤_ ⟶ _≥_
neg-mono-≤ {p@record{}} {q@record{}} (*≤* p≤q) = *≤* $ begin
ℤ.- ↥ q ℤ.* ↧ p ≡˘⟨ ℤ.neg-distribˡ-* (↥ q) (↧ p) ⟩
ℤ.- (↥ q ℤ.* ↧ p) ≤⟨ ℤ.neg-mono-≤ p≤q ⟩
ℤ.- (↥ p ℤ.* ↧ q) ≡⟨ ℤ.neg-distribˡ-* (↥ p) (↧ q) ⟩
ℤ.- ↥ p ℤ.* ↧ q ∎ where open ℤ.≤-Reasoning
neg-cancel-≤ : ∀ {p q} → - p ≤ - q → q ≤ p
neg-cancel-≤ {p@record{}} {q@record{}} (*≤* -↥p↧q≤-↥q↧p) = *≤* $ begin
↥ q ℤ.* ↧ p ≡˘⟨ ℤ.neg-involutive (↥ q ℤ.* ↧ p) ⟩
ℤ.- ℤ.- (↥ q ℤ.* ↧ p) ≡⟨ cong ℤ.-_ (ℤ.neg-distribˡ-* (↥ q) (↧ p)) ⟩
ℤ.- ((ℤ.- ↥ q) ℤ.* ↧ p) ≤⟨ ℤ.neg-mono-≤ -↥p↧q≤-↥q↧p ⟩
ℤ.- ((ℤ.- ↥ p) ℤ.* ↧ q) ≡˘⟨ cong ℤ.-_ (ℤ.neg-distribˡ-* (↥ p) (↧ q)) ⟩
ℤ.- ℤ.- (↥ p ℤ.* ↧ q) ≡⟨ ℤ.neg-involutive (↥ p ℤ.* ↧ q) ⟩
↥ p ℤ.* ↧ q ∎
where
open ℤ.≤-Reasoning
p≤q⇒p-q≤0 : ∀ {p q} → p ≤ q → p - q ≤ 0ℚᵘ
p≤q⇒p-q≤0 {p} {q} p≤q = begin
p - q ≤⟨ +-monoˡ-≤ (- q) p≤q ⟩
q - q ≈⟨ +-inverseʳ q ⟩
0ℚᵘ ∎ where open ≤-Reasoning
p-q≤0⇒p≤q : ∀ {p q} → p - q ≤ 0ℚᵘ → p ≤ q
p-q≤0⇒p≤q {p} {q} p-q≤0 = begin
p ≡˘⟨ +-identityʳ-≡ p ⟩
p + 0ℚᵘ ≈⟨ +-congʳ p (≃-sym (+-inverseˡ q)) ⟩
p + (- q + q) ≡˘⟨ +-assoc-≡ p (- q) q ⟩
(p - q) + q ≤⟨ +-monoˡ-≤ q p-q≤0 ⟩
0ℚᵘ + q ≡⟨ +-identityˡ-≡ q ⟩
q ∎ where open ≤-Reasoning
p≤q⇒0≤q-p : ∀ {p q} → p ≤ q → 0ℚᵘ ≤ q - p
p≤q⇒0≤q-p {p} {q} p≤q = begin
0ℚᵘ ≈⟨ ≃-sym (+-inverseʳ p) ⟩
p - p ≤⟨ +-monoˡ-≤ (- p) p≤q ⟩
q - p ∎ where open ≤-Reasoning
0≤q-p⇒p≤q : ∀ {p q} → 0ℚᵘ ≤ q - p → p ≤ q
0≤q-p⇒p≤q {p} {q} 0≤p-q = begin
p ≡˘⟨ +-identityˡ-≡ p ⟩
0ℚᵘ + p ≤⟨ +-monoˡ-≤ p 0≤p-q ⟩
q - p + p ≡⟨ +-assoc-≡ q (- p) p ⟩
q + (- p + p) ≈⟨ +-congʳ q (+-inverseˡ p) ⟩
q + 0ℚᵘ ≡⟨ +-identityʳ-≡ q ⟩
q ∎ where open ≤-Reasoning
+-isMagma : IsMagma _≃_ _+_
+-isMagma = record
{ isEquivalence = ≃-isEquivalence
; ∙-cong = +-cong
}
+-isSemigroup : IsSemigroup _≃_ _+_
+-isSemigroup = record
{ isMagma = +-isMagma
; assoc = +-assoc
}
+-0-isMonoid : IsMonoid _≃_ _+_ 0ℚᵘ
+-0-isMonoid = record
{ isSemigroup = +-isSemigroup
; identity = +-identity
}
+-0-isCommutativeMonoid : IsCommutativeMonoid _≃_ _+_ 0ℚᵘ
+-0-isCommutativeMonoid = record
{ isMonoid = +-0-isMonoid
; comm = +-comm
}
+-0-isGroup : IsGroup _≃_ _+_ 0ℚᵘ (-_)
+-0-isGroup = record
{ isMonoid = +-0-isMonoid
; inverse = +-inverse
; ⁻¹-cong = -‿cong
}
+-0-isAbelianGroup : IsAbelianGroup _≃_ _+_ 0ℚᵘ (-_)
+-0-isAbelianGroup = record
{ isGroup = +-0-isGroup
; comm = +-comm
}
+-magma : Magma 0ℓ 0ℓ
+-magma = record
{ isMagma = +-isMagma
}
+-semigroup : Semigroup 0ℓ 0ℓ
+-semigroup = record
{ isSemigroup = +-isSemigroup
}
+-0-monoid : Monoid 0ℓ 0ℓ
+-0-monoid = record
{ isMonoid = +-0-isMonoid
}
+-0-commutativeMonoid : CommutativeMonoid 0ℓ 0ℓ
+-0-commutativeMonoid = record
{ isCommutativeMonoid = +-0-isCommutativeMonoid
}
+-0-group : Group 0ℓ 0ℓ
+-0-group = record
{ isGroup = +-0-isGroup
}
+-0-abelianGroup : AbelianGroup 0ℓ 0ℓ
+-0-abelianGroup = record
{ isAbelianGroup = +-0-isAbelianGroup
}
*-rawMagma : RawMagma 0ℓ 0ℓ
*-rawMagma = record
{ _≈_ = _≃_
; _∙_ = _*_
}
*-rawMonoid : RawMonoid 0ℓ 0ℓ
*-rawMonoid = record
{ _≈_ = _≃_
; _∙_ = _*_
; ε = 1ℚᵘ
}
*-cong : Congruent₂ _≃_ _*_
*-cong {x@record{}} {y@record{}} {u@record{}} {v@record{}} (*≡* ↥x↧y≡↥y↧x) (*≡* ↥u↧v≡↥v↧u) = *≡* (begin
(↥ x ℤ.* ↥ u) ℤ.* (↧ y ℤ.* ↧ v) ≡⟨ solve 4 (λ ↥x ↥u ↧y ↧v →
(↥x :* ↥u) :* (↧y :* ↧v) :=
(↥u :* ↧v) :* (↥x :* ↧y))
refl (↥ x) (↥ u) (↧ y) (↧ v) ⟩
(↥ u ℤ.* ↧ v) ℤ.* (↥ x ℤ.* ↧ y) ≡⟨ cong₂ ℤ._*_ ↥u↧v≡↥v↧u ↥x↧y≡↥y↧x ⟩
(↥ v ℤ.* ↧ u) ℤ.* (↥ y ℤ.* ↧ x) ≡⟨ solve 4 (λ ↥v ↧u ↥y ↧x →
(↥v :* ↧u) :* (↥y :* ↧x) :=
(↥y :* ↥v) :* (↧x :* ↧u))
refl (↥ v) (↧ u) (↥ y) (↧ x) ⟩
(↥ y ℤ.* ↥ v) ℤ.* (↧ x ℤ.* ↧ u) ∎)
where open ≡-Reasoning; open ℤ-solver
*-congˡ : LeftCongruent _≃_ _*_
*-congˡ {p} q≃r = *-cong (≃-refl {p}) q≃r
*-congʳ : RightCongruent _≃_ _*_
*-congʳ {p} q≃r = *-cong q≃r (≃-refl {p})
*-assoc-↥ : Associative (_≡_ on ↥_) _*_
*-assoc-↥ p@record{} q@record{} r@record{} = ℤ.*-assoc (↥ p) (↥ q) (↥ r)
*-assoc-↧ : Associative (_≡_ on ↧ₙ_) _*_
*-assoc-↧ p@record{} q@record{} r@record{} = ℕ.*-assoc (↧ₙ p) (↧ₙ q) (↧ₙ r)
*-assoc-≡ : Associative _≡_ _*_
*-assoc-≡ p q r = ↥↧≡⇒≡ (*-assoc-↥ p q r) (*-assoc-↧ p q r)
*-assoc : Associative _≃_ _*_
*-assoc p q r = ≃-reflexive (*-assoc-≡ p q r)
*-comm-↥ : Commutative (_≡_ on ↥_) _*_
*-comm-↥ p@record{} q@record{} = ℤ.*-comm (↥ p) (↥ q)
*-comm-↧ : Commutative (_≡_ on ↧ₙ_) _*_
*-comm-↧ p@record{} q@record{} = ℕ.*-comm (↧ₙ p) (↧ₙ q)
*-comm-≡ : Commutative _≡_ _*_
*-comm-≡ p q = ↥↧≡⇒≡ (*-comm-↥ p q) (*-comm-↧ p q)
*-comm : Commutative _≃_ _*_
*-comm p q = ≃-reflexive (*-comm-≡ p q)
*-identityˡ-≡ : LeftIdentity _≡_ 1ℚᵘ _*_
*-identityˡ-≡ p@record{} = ↥↧≡⇒≡ (ℤ.*-identityˡ (↥ p)) (ℕ.+-identityʳ (↧ₙ p))
*-identityʳ-≡ : RightIdentity _≡_ 1ℚᵘ _*_
*-identityʳ-≡ = comm+idˡ⇒idʳ *-comm-≡ {e = 1ℚᵘ} *-identityˡ-≡
*-identity-≡ : Identity _≡_ 1ℚᵘ _*_
*-identity-≡ = *-identityˡ-≡ , *-identityʳ-≡
*-identityˡ : LeftIdentity _≃_ 1ℚᵘ _*_
*-identityˡ p = ≃-reflexive (*-identityˡ-≡ p)
*-identityʳ : RightIdentity _≃_ 1ℚᵘ _*_
*-identityʳ p = ≃-reflexive (*-identityʳ-≡ p)
*-identity : Identity _≃_ 1ℚᵘ _*_
*-identity = *-identityˡ , *-identityʳ
*-inverseˡ : ∀ p .{{_ : NonZero p}} → (1/ p) * p ≃ 1ℚᵘ
*-inverseˡ p@(mkℚᵘ -[1+ n ] d) = *-inverseˡ (mkℚᵘ +[1+ n ] d)
*-inverseˡ p@(mkℚᵘ +[1+ n ] d) = *≡* $ cong +[1+_] $ begin
(n ℕ.+ d ℕ.* suc n) ℕ.* 1 ≡⟨ ℕ.*-identityʳ _ ⟩
(n ℕ.+ d ℕ.* suc n) ≡⟨ cong (n ℕ.+_) (ℕ.*-suc d n) ⟩
(n ℕ.+ (d ℕ.+ d ℕ.* n)) ≡⟨ solve 2 (λ n d → n :+ (d :+ d :* n) := d :+ (n :+ n :* d)) refl n d ⟩
(d ℕ.+ (n ℕ.+ n ℕ.* d)) ≡⟨ cong (d ℕ.+_) (sym (ℕ.*-suc n d)) ⟩
d ℕ.+ n ℕ.* suc d ≡˘⟨ ℕ.+-identityʳ _ ⟩
d ℕ.+ n ℕ.* suc d ℕ.+ 0 ∎
where open ≡-Reasoning; open ℕ-solver
*-inverseʳ : ∀ p .{{_ : NonZero p}} → p * 1/ p ≃ 1ℚᵘ
*-inverseʳ p = ≃-trans (*-comm p (1/ p)) (*-inverseˡ p)
*-zeroˡ : LeftZero _≃_ 0ℚᵘ _*_
*-zeroˡ p@record{} = *≡* refl
*-zeroʳ : RightZero _≃_ 0ℚᵘ _*_
*-zeroʳ = Consequences.comm+zeˡ⇒zeʳ ≃-setoid *-comm *-zeroˡ
*-zero : Zero _≃_ 0ℚᵘ _*_
*-zero = *-zeroˡ , *-zeroʳ
*-distribˡ-+ : _DistributesOverˡ_ _≃_ _*_ _+_
*-distribˡ-+ p@record{} q@record{} r@record{} =
let ↥p = ↥ p; ↧p = ↧ p
↥q = ↥ q; ↧q = ↧ q
↥r = ↥ r; ↧r = ↧ r
eq : (↥p ℤ.* (↥q ℤ.* ↧r ℤ.+ ↥r ℤ.* ↧q)) ℤ.* (↧p ℤ.* ↧q ℤ.* (↧p ℤ.* ↧r)) ≡
(↥p ℤ.* ↥q ℤ.* (↧p ℤ.* ↧r) ℤ.+ ↥p ℤ.* ↥r ℤ.* (↧p ℤ.* ↧q)) ℤ.* (↧p ℤ.* (↧q ℤ.* ↧r))
eq = solve 6 (λ ↥p ↧p ↥q d e f →
(↥p :* (↥q :* f :+ e :* d)) :* (↧p :* d :* (↧p :* f)) :=
(↥p :* ↥q :* (↧p :* f) :+ ↥p :* e :* (↧p :* d)) :* (↧p :* (d :* f)))
refl ↥p ↧p ↥q ↧q ↥r ↧r
in *≡* eq where open ℤ-solver
*-distribʳ-+ : _DistributesOverʳ_ _≃_ _*_ _+_
*-distribʳ-+ = Consequences.comm+distrˡ⇒distrʳ ≃-setoid +-cong *-comm *-distribˡ-+
*-distrib-+ : _DistributesOver_ _≃_ _*_ _+_
*-distrib-+ = *-distribˡ-+ , *-distribʳ-+
neg-distribˡ-* : ∀ p q → - (p * q) ≃ - p * q
neg-distribˡ-* p@record{} q@record{} =
*≡* $ cong (ℤ._* (↧ p ℤ.* ↧ q)) $ ℤ.neg-distribˡ-* (↥ p) (↥ q)
neg-distribʳ-* : ∀ p q → - (p * q) ≃ p * - q
neg-distribʳ-* p@record{} q@record{} =
*≡* $ cong (ℤ._* (↧ p ℤ.* ↧ q)) $ ℤ.neg-distribʳ-* (↥ p) (↥ q)
*-cancelˡ-/ : ∀ p {q r} .{{_ : ℕ.NonZero r}} .{{_ : ℕ.NonZero (p ℕ.* r)}} →
((ℤ.+ p ℤ.* q) / (p ℕ.* r)) ≃ (q / r)
*-cancelˡ-/ p {q} {r} = *≡* (begin-equality
(↥ ((ℤ.+ p ℤ.* q) / (p ℕ.* r))) ℤ.* (↧ (q / r)) ≡⟨ cong (ℤ._* ↧ (q / r)) (↥[n/d]≡n (ℤ.+ p ℤ.* q) (p ℕ.* r)) ⟩
(ℤ.+ p ℤ.* q) ℤ.* (↧ (q / r)) ≡⟨ cong ((ℤ.+ p ℤ.* q) ℤ.*_) (↧[n/d]≡d q r) ⟩
(ℤ.+ p ℤ.* q) ℤ.* ℤ.+ r ≡⟨ xy∙z≈y∙xz (ℤ.+ p) q (ℤ.+ r) ⟩
(q ℤ.* (ℤ.+ p ℤ.* ℤ.+ r)) ≡˘⟨ cong (ℤ._* (ℤ.+ p ℤ.* ℤ.+ r)) (↥[n/d]≡n q r) ⟩
(↥ (q / r)) ℤ.* (ℤ.+ p ℤ.* ℤ.+ r) ≡⟨ cong (↥ (q / r) ℤ.*_) (ℤ.pos-distrib-* p r) ⟩
(↥ (q / r)) ℤ.* (ℤ.+ (p ℕ.* r)) ≡˘⟨ cong (↥ (q / r) ℤ.*_) (↧[n/d]≡d (ℤ.+ p ℤ.* q) (p ℕ.* r)) ⟩
(↥ (q / r)) ℤ.* (↧ ((ℤ.+ p ℤ.* q) / (p ℕ.* r))) ∎)
where open ℤ.≤-Reasoning
*-cancelʳ-/ : ∀ p {q r} .{{_ : ℕ.NonZero r}} .{{_ : ℕ.NonZero (r ℕ.* p)}} →
((q ℤ.* ℤ.+ p) / (r ℕ.* p)) ≃ (q / r)
*-cancelʳ-/ p {q} {r} rewrite ℕ.*-comm r p | ℤ.*-comm q (ℤ.+ p) = *-cancelˡ-/ p
private
reorder₁ : ∀ a b c d → a ℤ.* b ℤ.* (c ℤ.* d) ≡ a ℤ.* c ℤ.* b ℤ.* d
reorder₁ = solve 4 (λ a b c d → (a :* b) :* (c :* d) := (a :* c) :* b :* d) refl
where open ℤ-solver
reorder₂ : ∀ a b c d → a ℤ.* b ℤ.* (c ℤ.* d) ≡ a ℤ.* c ℤ.* (b ℤ.* d)
reorder₂ = solve 4 (λ a b c d → (a :* b) :* (c :* d) := (a :* c) :* (b :* d)) refl
where open ℤ-solver
+▹-nonNeg : ∀ n → ℤ.NonNegative (Sign.+ ℤ.◃ n)
+▹-nonNeg 0 = _
+▹-nonNeg (suc _) = _
*-cancelʳ-≤-pos : ∀ r .{{_ : Positive r}} → p * r ≤ q * r → p ≤ q
*-cancelʳ-≤-pos {p@record{}} {q@record{}} r@(mkℚᵘ +[1+ _ ] _) (*≤* x≤y) =
*≤* $ ℤ.*-cancelʳ-≤-pos _ _ (↥ r ℤ.* ↧ r) $ begin
(↥ p ℤ.* ↧ q) ℤ.* (↥ r ℤ.* ↧ r) ≡⟨ reorder₂ (↥ p) _ _ (↧ r) ⟩
(↥ p ℤ.* ↥ r) ℤ.* (↧ q ℤ.* ↧ r) ≤⟨ x≤y ⟩
(↥ q ℤ.* ↥ r) ℤ.* (↧ p ℤ.* ↧ r) ≡⟨ reorder₂ (↥ q) _ _ (↧ r) ⟩
(↥ q ℤ.* ↧ p) ℤ.* (↥ r ℤ.* ↧ r) ∎ where open ℤ.≤-Reasoning
*-cancelˡ-≤-pos : ∀ r .{{_ : Positive r}} → r * p ≤ r * q → p ≤ q
*-cancelˡ-≤-pos {p} {q} r rewrite *-comm-≡ r p | *-comm-≡ r q = *-cancelʳ-≤-pos r
*-cancelʳ-≤-neg : ∀ r .{{_ : Negative r}} → p * r ≤ q * r → q ≤ p
*-cancelʳ-≤-neg {p} {q} r@(mkℚᵘ -[1+ _ ] _) pr≤qr = neg-cancel-≤ (*-cancelʳ-≤-pos (- r) (begin
- p * - r ≈˘⟨ neg-distribˡ-* p (- r) ⟩
- (p * - r) ≈˘⟨ -‿cong (neg-distribʳ-* p r) ⟩
- - (p * r) ≈⟨ neg-involutive (p * r) ⟩
p * r ≤⟨ pr≤qr ⟩
q * r ≈˘⟨ neg-involutive (q * r) ⟩
- - (q * r) ≈⟨ -‿cong (neg-distribʳ-* q r) ⟩
- (q * - r) ≈⟨ neg-distribˡ-* q (- r) ⟩
- q * - r ∎))
where open ≤-Reasoning
*-cancelˡ-≤-neg : ∀ r .{{_ : Negative r}} → r * p ≤ r * q → q ≤ p
*-cancelˡ-≤-neg {p} {q} r rewrite *-comm-≡ r p | *-comm-≡ r q = *-cancelʳ-≤-neg r
*-monoˡ-≤-nonNeg : ∀ r .{{_ : NonNegative r}} → (_* r) Preserves _≤_ ⟶ _≤_
*-monoˡ-≤-nonNeg r@(mkℚᵘ (ℤ.+ n) _) {p@record{}} {q@record{}} (*≤* x<y) = *≤* $ begin
↥ p ℤ.* ↥ r ℤ.* (↧ q ℤ.* ↧ r) ≡⟨ reorder₂ (↥ p) _ _ _ ⟩
l₁ ℤ.* (ℤ.+ n ℤ.* ↧ r) ≡⟨ cong (l₁ ℤ.*_) (ℤ.pos-distrib-* n _) ⟩
l₁ ℤ.* ℤ.+ (n ℕ.* ↧ₙ r) ≤⟨ ℤ.*-monoʳ-≤-nonNeg (ℤ.+ (n ℕ.* ↧ₙ r)) x<y ⟩
l₂ ℤ.* ℤ.+ (n ℕ.* ↧ₙ r) ≡˘⟨ cong (l₂ ℤ.*_) (ℤ.pos-distrib-* n _) ⟩
l₂ ℤ.* (ℤ.+ n ℤ.* ↧ r) ≡⟨ reorder₂ (↥ q) _ _ _ ⟩
↥ q ℤ.* ↥ r ℤ.* (↧ p ℤ.* ↧ r) ∎
where open ℤ.≤-Reasoning; l₁ = ↥ p ℤ.* ↧ q ; l₂ = ↥ q ℤ.* ↧ p
*-monoʳ-≤-nonNeg : ∀ r .{{_ : NonNegative r}} → (r *_) Preserves _≤_ ⟶ _≤_
*-monoʳ-≤-nonNeg r {p} {q} rewrite *-comm-≡ r p | *-comm-≡ r q = *-monoˡ-≤-nonNeg r
*-mono-≤-nonNeg : ∀ {p q r s} .{{_ : NonNegative p}} .{{_ : NonNegative r}} →
p ≤ q → r ≤ s → p * r ≤ q * s
*-mono-≤-nonNeg {p} {q} {r} {s} p≤q r≤s = begin
p * r ≤⟨ *-monoˡ-≤-nonNeg r p≤q ⟩
q * r ≤⟨ *-monoʳ-≤-nonNeg q {{nonNeg≤⇒nonNeg p≤q}} r≤s ⟩
q * s ∎
where open ≤-Reasoning
*-monoˡ-≤-nonPos : ∀ r .{{_ : NonPositive r}} → (_* r) Preserves _≤_ ⟶ _≥_
*-monoˡ-≤-nonPos r {p} {q} p≤q = begin
q * r ≈˘⟨ neg-involutive (q * r) ⟩
- - (q * r) ≈⟨ -‿cong (neg-distribʳ-* q r) ⟩
- (q * - r) ≤⟨ neg-mono-≤ (*-monoˡ-≤-nonNeg (- r) {{ -r≥0}} p≤q) ⟩
- (p * - r) ≈˘⟨ -‿cong (neg-distribʳ-* p r) ⟩
- - (p * r) ≈⟨ neg-involutive (p * r) ⟩
p * r ∎
where open ≤-Reasoning; -r≥0 = nonNegative (neg-mono-≤ (nonPositive⁻¹ r))
*-monoʳ-≤-nonPos : ∀ r .{{_ : NonPositive r}} → (r *_) Preserves _≤_ ⟶ _≥_
*-monoʳ-≤-nonPos r {p} {q} rewrite *-comm-≡ r q | *-comm-≡ r p = *-monoˡ-≤-nonPos r
*-monoˡ-<-pos : ∀ r .{{_ : Positive r}} → (_* r) Preserves _<_ ⟶ _<_
*-monoˡ-<-pos r@record{} {p@record{}} {q@record{}} (*<* x<y) = *<* $ begin-strict
↥ p ℤ.* ↥ r ℤ.* (↧ q ℤ.* ↧ r) ≡⟨ reorder₁ (↥ p) _ _ _ ⟩
↥ p ℤ.* ↧ q ℤ.* ↥ r ℤ.* ↧ r <⟨ ℤ.*-monoʳ-<-pos (↧ r) (ℤ.*-monoʳ-<-pos (↥ r) x<y) ⟩
↥ q ℤ.* ↧ p ℤ.* ↥ r ℤ.* ↧ r ≡˘⟨ reorder₁ (↥ q) _ _ _ ⟩
↥ q ℤ.* ↥ r ℤ.* (↧ p ℤ.* ↧ r) ∎ where open ℤ.≤-Reasoning
*-monoʳ-<-pos : ∀ r .{{_ : Positive r}} → (r *_) Preserves _<_ ⟶ _<_
*-monoʳ-<-pos r {p} {q} rewrite *-comm-≡ r p | *-comm-≡ r q = *-monoˡ-<-pos r
*-mono-<-nonNeg : ∀ {p q r s} .{{_ : NonNegative p}} .{{_ : NonNegative r}} →
p < q → r < s → p * r < q * s
*-mono-<-nonNeg {p} {q} {r} {s} p<q r<s = begin-strict
p * r ≤⟨ *-monoˡ-≤-nonNeg r (<⇒≤ p<q) ⟩
q * r <⟨ *-monoʳ-<-pos q {{nonNeg<⇒pos p<q}} r<s ⟩
q * s ∎
where open ≤-Reasoning
*-cancelʳ-<-nonNeg : ∀ r .{{_ : NonNegative r}} → p * r < q * r → p < q
*-cancelʳ-<-nonNeg {p@record{}} {q@record{}} r@(mkℚᵘ (ℤ.+ _) _) (*<* x<y) =
*<* $ ℤ.*-cancelʳ-<-nonNeg (↥ r ℤ.* ↧ r) {{+▹-nonNeg _}} $ begin-strict
(↥ p ℤ.* ↧ q) ℤ.* (↥ r ℤ.* ↧ r) ≡⟨ reorder₂ (↥ p) _ _ (↧ r) ⟩
(↥ p ℤ.* ↥ r) ℤ.* (↧ q ℤ.* ↧ r) <⟨ x<y ⟩
(↥ q ℤ.* ↥ r) ℤ.* (↧ p ℤ.* ↧ r) ≡⟨ reorder₂ (↥ q) _ _ (↧ r) ⟩
(↥ q ℤ.* ↧ p) ℤ.* (↥ r ℤ.* ↧ r) ∎ where open ℤ.≤-Reasoning
*-cancelˡ-<-nonNeg : ∀ r .{{_ : NonNegative r}} → r * p < r * q → p < q
*-cancelˡ-<-nonNeg {p} {q} r rewrite *-comm-≡ r p | *-comm-≡ r q = *-cancelʳ-<-nonNeg r
*-monoˡ-<-neg : ∀ r .{{_ : Negative r}} → (_* r) Preserves _<_ ⟶ _>_
*-monoˡ-<-neg r {p} {q} p<q = begin-strict
q * r ≈˘⟨ neg-involutive (q * r) ⟩
- - (q * r) ≈⟨ -‿cong (neg-distribʳ-* q r) ⟩
- (q * - r) <⟨ neg-mono-< (*-monoˡ-<-pos (- r) {{ -r>0}} p<q) ⟩
- (p * - r) ≈˘⟨ -‿cong (neg-distribʳ-* p r) ⟩
- - (p * r) ≈⟨ neg-involutive (p * r) ⟩
p * r ∎
where open ≤-Reasoning; -r>0 = positive (neg-mono-< (negative⁻¹ r))
*-monoʳ-<-neg : ∀ r .{{_ : Negative r}} → (r *_) Preserves _<_ ⟶ _>_
*-monoʳ-<-neg r {p} {q} rewrite *-comm-≡ r q | *-comm-≡ r p = *-monoˡ-<-neg r
*-cancelˡ-<-nonPos : ∀ r .{{_ : NonPositive r}} → r * p < r * q → q < p
*-cancelˡ-<-nonPos {p} {q} r rp<rq =
*-cancelˡ-<-nonNeg (- r) {{ -r≥0}} $ begin-strict
- r * q ≈˘⟨ neg-distribˡ-* r q ⟩
- (r * q) <⟨ neg-mono-< rp<rq ⟩
- (r * p) ≈⟨ neg-distribˡ-* r p ⟩
- r * p ∎
where open ≤-Reasoning; -r≥0 = nonNegative (neg-mono-≤ (nonPositive⁻¹ r))
*-cancelʳ-<-nonPos : ∀ r .{{_ : NonPositive r}} → p * r < q * r → q < p
*-cancelʳ-<-nonPos {p} {q} r rewrite *-comm-≡ p r | *-comm-≡ q r = *-cancelˡ-<-nonPos r
pos*pos⇒pos : ∀ p .{{_ : Positive p}} →
∀ q .{{_ : Positive q}} →
Positive (p * q)
pos*pos⇒pos p q = positive
(*-mono-<-nonNeg (positive⁻¹ p) (positive⁻¹ q))
nonNeg*nonNeg⇒nonNeg : ∀ p .{{_ : NonNegative p}} →
∀ q .{{_ : NonNegative q}} →
NonNegative (p * q)
nonNeg*nonNeg⇒nonNeg p q = nonNegative
(*-mono-≤-nonNeg (nonNegative⁻¹ p) (nonNegative⁻¹ q))
*-isMagma : IsMagma _≃_ _*_
*-isMagma = record
{ isEquivalence = ≃-isEquivalence
; ∙-cong = *-cong
}
*-isSemigroup : IsSemigroup _≃_ _*_
*-isSemigroup = record
{ isMagma = *-isMagma
; assoc = *-assoc
}
*-1-isMonoid : IsMonoid _≃_ _*_ 1ℚᵘ
*-1-isMonoid = record
{ isSemigroup = *-isSemigroup
; identity = *-identity
}
*-1-isCommutativeMonoid : IsCommutativeMonoid _≃_ _*_ 1ℚᵘ
*-1-isCommutativeMonoid = record
{ isMonoid = *-1-isMonoid
; comm = *-comm
}
+-*-isRing : IsRing _≃_ _+_ _*_ -_ 0ℚᵘ 1ℚᵘ
+-*-isRing = record
{ +-isAbelianGroup = +-0-isAbelianGroup
; *-cong = *-cong
; *-assoc = *-assoc
; *-identity = *-identity
; distrib = *-distrib-+
; zero = *-zero
}
+-*-isCommutativeRing : IsCommutativeRing _≃_ _+_ _*_ -_ 0ℚᵘ 1ℚᵘ
+-*-isCommutativeRing = record
{ isRing = +-*-isRing
; *-comm = *-comm
}
*-magma : Magma 0ℓ 0ℓ
*-magma = record
{ isMagma = *-isMagma
}
*-semigroup : Semigroup 0ℓ 0ℓ
*-semigroup = record
{ isSemigroup = *-isSemigroup
}
*-1-monoid : Monoid 0ℓ 0ℓ
*-1-monoid = record
{ isMonoid = *-1-isMonoid
}
*-1-commutativeMonoid : CommutativeMonoid 0ℓ 0ℓ
*-1-commutativeMonoid = record
{ isCommutativeMonoid = *-1-isCommutativeMonoid
}
+-*-ring : Ring 0ℓ 0ℓ
+-*-ring = record
{ isRing = +-*-isRing
}
+-*-commutativeRing : CommutativeRing 0ℓ 0ℓ
+-*-commutativeRing = record
{ isCommutativeRing = +-*-isCommutativeRing
}
private
p>1⇒p≢0 : p > 1ℚᵘ → NonZero p
p>1⇒p≢0 {p} p>1 = pos⇒nonZero p {{positive (<-trans (*<* (ℤ.+<+ ℕ.≤-refl)) p>1)}}
1/nonZero⇒nonZero : ∀ p .{{_ : NonZero p}} → NonZero (1/ p)
1/nonZero⇒nonZero (mkℚᵘ (+[1+ _ ]) _) = _
1/nonZero⇒nonZero (mkℚᵘ (-[1+ _ ]) _) = _
1/-involutive-≡ : ∀ p .{{_ : NonZero p}} →
(1/ (1/ p)) {{1/nonZero⇒nonZero p}} ≡ p
1/-involutive-≡ (mkℚᵘ +[1+ n ] d-1) = refl
1/-involutive-≡ (mkℚᵘ -[1+ n ] d-1) = refl
1/-involutive : ∀ p .{{_ : NonZero p}} →
(1/ (1/ p)) {{1/nonZero⇒nonZero p}} ≃ p
1/-involutive p = ≃-reflexive (1/-involutive-≡ p)
1/pos⇒pos : ∀ p .{{p>0 : Positive p}} → Positive ((1/ p) {{pos⇒nonZero p}})
1/pos⇒pos (mkℚᵘ +[1+ n ] d-1) = _
1/neg⇒neg : ∀ p .{{p<0 : Negative p}} → Negative ((1/ p) {{neg⇒nonZero p}})
1/neg⇒neg (mkℚᵘ -[1+ n ] d-1) = _
p>1⇒1/p<1 : ∀ {p} → (p>1 : p > 1ℚᵘ) → (1/ p) {{p>1⇒p≢0 p>1}} < 1ℚᵘ
p>1⇒1/p<1 {p} p>1 = lemma′ p (p>1⇒p≢0 p>1) p>1
where
lemma′ : ∀ p p≢0 → p > 1ℚᵘ → (1/ p) {{p≢0}} < 1ℚᵘ
lemma′ (mkℚᵘ n@(+[1+ _ ]) d-1) _ (*<* ↥p1>1↧p) = *<* (begin-strict
↥ (1/ mkℚᵘ n d-1) ℤ.* 1ℤ ≡⟨⟩
+[1+ d-1 ] ℤ.* 1ℤ ≡⟨ ℤ.*-comm +[1+ d-1 ] 1ℤ ⟩
1ℤ ℤ.* +[1+ d-1 ] <⟨ ↥p1>1↧p ⟩
n ℤ.* 1ℤ ≡⟨ ℤ.*-comm n 1ℤ ⟩
1ℤ ℤ.* n ≡⟨⟩
(↥ 1ℚᵘ) ℤ.* (↧ (1/ mkℚᵘ n d-1)) ∎)
where open ℤ.≤-Reasoning
1/-antimono-≤-pos : ∀ {p q} .{{_ : Positive p}} .{{_ : Positive q}} →
p ≤ q → (1/ q) {{pos⇒nonZero q}} ≤ (1/ p) {{pos⇒nonZero p}}
1/-antimono-≤-pos {p} {q} p≤q = begin
1/q ≈˘⟨ *-identityˡ 1/q ⟩
1ℚᵘ * 1/q ≈˘⟨ *-congʳ (*-inverseˡ p) ⟩
(1/p * p) * 1/q ≤⟨ *-monoˡ-≤-nonNeg 1/q (*-monoʳ-≤-nonNeg 1/p p≤q) ⟩
(1/p * q) * 1/q ≈⟨ *-assoc 1/p q 1/q ⟩
1/p * (q * 1/q) ≈⟨ *-congˡ {1/p} (*-inverseʳ q) ⟩
1/p * 1ℚᵘ ≈⟨ *-identityʳ (1/p) ⟩
1/p ∎
where
open ≤-Reasoning
instance
_ = pos⇒nonZero p
_ = pos⇒nonZero q
1/p = 1/ p
1/q = 1/ q
instance
1/p≥0 : NonNegative 1/p
1/p≥0 = pos⇒nonNeg 1/p {{1/pos⇒pos p}}
1/q≥0 : NonNegative 1/q
1/q≥0 = pos⇒nonNeg 1/q {{1/pos⇒pos q}}
p≤q⇒p⊔q≃q : p ≤ q → p ⊔ q ≃ q
p≤q⇒p⊔q≃q {p@record{}} {q@record{}} p≤q with p ≤ᵇ q | inspect (p ≤ᵇ_) q
... | true | _ = ≃-refl
... | false | [ p≰q ] = contradiction (≤⇒≤ᵇ p≤q) (subst (¬_ ∘ T) (sym p≰q) λ())
p≥q⇒p⊔q≃p : p ≥ q → p ⊔ q ≃ p
p≥q⇒p⊔q≃p {p@record{}} {q@record{}} p≥q with p ≤ᵇ q | inspect (p ≤ᵇ_) q
... | true | [ p≤q ] = ≤-antisym p≥q (≤ᵇ⇒≤ (subst T (sym p≤q) _))
... | false | [ p≤q ] = ≃-refl
p≤q⇒p⊓q≃p : p ≤ q → p ⊓ q ≃ p
p≤q⇒p⊓q≃p {p@record{}} {q@record{}} p≤q with p ≤ᵇ q | inspect (p ≤ᵇ_) q
... | true | _ = ≃-refl
... | false | [ p≰q ] = contradiction (≤⇒≤ᵇ p≤q) (subst (¬_ ∘ T) (sym p≰q) λ())
p≥q⇒p⊓q≃q : p ≥ q → p ⊓ q ≃ q
p≥q⇒p⊓q≃q {p@record{}} {q@record{}} p≥q with p ≤ᵇ q | inspect (p ≤ᵇ_) q
... | true | [ p≤q ] = ≤-antisym (≤ᵇ⇒≤ (subst T (sym p≤q) _)) p≥q
... | false | [ p≤q ] = ≃-refl
⊓-operator : MinOperator ≤-totalPreorder
⊓-operator = record
{ x≤y⇒x⊓y≈x = p≤q⇒p⊓q≃p
; x≥y⇒x⊓y≈y = p≥q⇒p⊓q≃q
}
⊔-operator : MaxOperator ≤-totalPreorder
⊔-operator = record
{ x≤y⇒x⊔y≈y = p≤q⇒p⊔q≃q
; x≥y⇒x⊔y≈x = p≥q⇒p⊔q≃p
}
private
module ⊓-⊔-properties = MinMaxOp ⊓-operator ⊔-operator
module ⊓-⊔-latticeProperties = LatticeMinMaxOp ⊓-operator ⊔-operator
open ⊓-⊔-properties public
using
( ⊓-congˡ
; ⊓-congʳ
; ⊓-cong
; ⊓-idem
; ⊓-sel
; ⊓-assoc
; ⊓-comm
; ⊔-congˡ
; ⊔-congʳ
; ⊔-cong
; ⊔-idem
; ⊔-sel
; ⊔-assoc
; ⊔-comm
; ⊓-distribˡ-⊔
; ⊓-distribʳ-⊔
; ⊓-distrib-⊔
; ⊔-distribˡ-⊓
; ⊔-distribʳ-⊓
; ⊔-distrib-⊓
; ⊓-absorbs-⊔
; ⊔-absorbs-⊓
; ⊔-⊓-absorptive
; ⊓-⊔-absorptive
; ⊓-isMagma
; ⊓-isSemigroup
; ⊓-isCommutativeSemigroup
; ⊓-isBand
; ⊓-isSelectiveMagma
; ⊔-isMagma
; ⊔-isSemigroup
; ⊔-isCommutativeSemigroup
; ⊔-isBand
; ⊔-isSelectiveMagma
; ⊓-magma
; ⊓-semigroup
; ⊓-band
; ⊓-commutativeSemigroup
; ⊓-selectiveMagma
; ⊔-magma
; ⊔-semigroup
; ⊔-band
; ⊔-commutativeSemigroup
; ⊔-selectiveMagma
; ⊓-triangulate
; ⊔-triangulate
; ⊓-glb
; ⊓-mono-≤
; ⊓-monoˡ-≤
; ⊓-monoʳ-≤
; ⊔-lub
; ⊔-mono-≤
; ⊔-monoˡ-≤
; ⊔-monoʳ-≤
)
renaming
( x⊓y≈y⇒y≤x to p⊓q≃q⇒q≤p
; x⊓y≈x⇒x≤y to p⊓q≃p⇒p≤q
; x⊔y≈y⇒x≤y to p⊔q≃q⇒p≤q
; x⊔y≈x⇒y≤x to p⊔q≃p⇒q≤p
; x⊓y≤x to p⊓q≤p
; x⊓y≤y to p⊓q≤q
; x≤y⇒x⊓z≤y to p≤q⇒p⊓r≤q
; x≤y⇒z⊓x≤y to p≤q⇒r⊓p≤q
; x≤y⊓z⇒x≤y to p≤q⊓r⇒p≤q
; x≤y⊓z⇒x≤z to p≤q⊓r⇒p≤r
; x≤x⊔y to p≤p⊔q
; x≤y⊔x to p≤q⊔p
; x≤y⇒x≤y⊔z to p≤q⇒p≤q⊔r
; x≤y⇒x≤z⊔y to p≤q⇒p≤r⊔q
; x⊔y≤z⇒x≤z to p⊔q≤r⇒p≤r
; x⊔y≤z⇒y≤z to p⊔q≤r⇒q≤r
; x⊓y≤x⊔y to p⊓q≤p⊔q
)
open ⊓-⊔-latticeProperties public
using
( ⊓-semilattice
; ⊔-semilattice
; ⊔-⊓-lattice
; ⊓-⊔-lattice
; ⊔-⊓-distributiveLattice
; ⊓-⊔-distributiveLattice
; ⊓-isSemilattice
; ⊔-isSemilattice
; ⊔-⊓-isLattice
; ⊓-⊔-isLattice
; ⊔-⊓-isDistributiveLattice
; ⊓-⊔-isDistributiveLattice
)
⊓-rawMagma : RawMagma _ _
⊓-rawMagma = Magma.rawMagma ⊓-magma
⊔-rawMagma : RawMagma _ _
⊔-rawMagma = Magma.rawMagma ⊔-magma
⊔-⊓-rawLattice : RawLattice _ _
⊔-⊓-rawLattice = Lattice.rawLattice ⊔-⊓-lattice
mono-≤-distrib-⊔ : ∀ {f} → f Preserves _≤_ ⟶ _≤_ →
∀ m n → f (m ⊔ n) ≃ f m ⊔ f n
mono-≤-distrib-⊔ pres = ⊓-⊔-properties.mono-≤-distrib-⊔ (mono⇒cong pres) pres
mono-≤-distrib-⊓ : ∀ {f} → f Preserves _≤_ ⟶ _≤_ →
∀ m n → f (m ⊓ n) ≃ f m ⊓ f n
mono-≤-distrib-⊓ pres = ⊓-⊔-properties.mono-≤-distrib-⊓ (mono⇒cong pres) pres
antimono-≤-distrib-⊓ : ∀ {f} → f Preserves _≤_ ⟶ _≥_ →
∀ m n → f (m ⊓ n) ≃ f m ⊔ f n
antimono-≤-distrib-⊓ pres = ⊓-⊔-properties.antimono-≤-distrib-⊓ (antimono⇒cong pres) pres
antimono-≤-distrib-⊔ : ∀ {f} → f Preserves _≤_ ⟶ _≥_ →
∀ m n → f (m ⊔ n) ≃ f m ⊓ f n
antimono-≤-distrib-⊔ pres = ⊓-⊔-properties.antimono-≤-distrib-⊔ (antimono⇒cong pres) pres
neg-distrib-⊔-⊓ : ∀ p q → - (p ⊔ q) ≃ - p ⊓ - q
neg-distrib-⊔-⊓ = antimono-≤-distrib-⊔ neg-mono-≤
neg-distrib-⊓-⊔ : ∀ p q → - (p ⊓ q) ≃ - p ⊔ - q
neg-distrib-⊓-⊔ = antimono-≤-distrib-⊓ neg-mono-≤
*-distribˡ-⊓-nonNeg : ∀ p .{{_ : NonNegative p}} → ∀ q r → p * (q ⊓ r) ≃ (p * q) ⊓ (p * r)
*-distribˡ-⊓-nonNeg p = mono-≤-distrib-⊓ (*-monoʳ-≤-nonNeg p)
*-distribʳ-⊓-nonNeg : ∀ p .{{_ : NonNegative p}} → ∀ q r → (q ⊓ r) * p ≃ (q * p) ⊓ (r * p)
*-distribʳ-⊓-nonNeg p = mono-≤-distrib-⊓ (*-monoˡ-≤-nonNeg p)
*-distribˡ-⊔-nonNeg : ∀ p .{{_ : NonNegative p}} → ∀ q r → p * (q ⊔ r) ≃ (p * q) ⊔ (p * r)
*-distribˡ-⊔-nonNeg p = mono-≤-distrib-⊔ (*-monoʳ-≤-nonNeg p)
*-distribʳ-⊔-nonNeg : ∀ p .{{_ : NonNegative p}} → ∀ q r → (q ⊔ r) * p ≃ (q * p) ⊔ (r * p)
*-distribʳ-⊔-nonNeg p = mono-≤-distrib-⊔ (*-monoˡ-≤-nonNeg p)
*-distribˡ-⊔-nonPos : ∀ p .{{_ : NonPositive p}} → ∀ q r → p * (q ⊔ r) ≃ (p * q) ⊓ (p * r)
*-distribˡ-⊔-nonPos p = antimono-≤-distrib-⊔ (*-monoʳ-≤-nonPos p)
*-distribʳ-⊔-nonPos : ∀ p .{{_ : NonPositive p}} → ∀ q r → (q ⊔ r) * p ≃ (q * p) ⊓ (r * p)
*-distribʳ-⊔-nonPos p = antimono-≤-distrib-⊔ (*-monoˡ-≤-nonPos p)
*-distribˡ-⊓-nonPos : ∀ p .{{_ : NonPositive p}} → ∀ q r → p * (q ⊓ r) ≃ (p * q) ⊔ (p * r)
*-distribˡ-⊓-nonPos p = antimono-≤-distrib-⊓ (*-monoʳ-≤-nonPos p)
*-distribʳ-⊓-nonPos : ∀ p .{{_ : NonPositive p}} → ∀ q r → (q ⊓ r) * p ≃ (q * p) ⊔ (r * p)
*-distribʳ-⊓-nonPos p = antimono-≤-distrib-⊓ (*-monoˡ-≤-nonPos p)
⊓-mono-< : _⊓_ Preserves₂ _<_ ⟶ _<_ ⟶ _<_
⊓-mono-< {p} {r} {q} {s} p<r q<s with ⊓-sel r s
... | inj₁ r⊓s≃r = <-respʳ-≃ (≃-sym r⊓s≃r) (≤-<-trans (p⊓q≤p p q) p<r)
... | inj₂ r⊓s≃s = <-respʳ-≃ (≃-sym r⊓s≃s) (≤-<-trans (p⊓q≤q p q) q<s)
⊔-mono-< : _⊔_ Preserves₂ _<_ ⟶ _<_ ⟶ _<_
⊔-mono-< {p} {r} {q} {s} p<r q<s with ⊔-sel p q
... | inj₁ p⊔q≃p = <-respˡ-≃ (≃-sym p⊔q≃p) (<-≤-trans p<r (p≤p⊔q r s))
... | inj₂ p⊔q≃q = <-respˡ-≃ (≃-sym p⊔q≃q) (<-≤-trans q<s (p≤q⊔p r s))
pos⊓pos⇒pos : ∀ p .{{_ : Positive p}} →
∀ q .{{_ : Positive q}} →
Positive (p ⊓ q)
pos⊓pos⇒pos p q = positive (⊓-mono-< (positive⁻¹ p) (positive⁻¹ q))
pos⊔pos⇒pos : ∀ p .{{_ : Positive p}} →
∀ q .{{_ : Positive q}} →
Positive (p ⊔ q)
pos⊔pos⇒pos p q = positive (⊔-mono-< (positive⁻¹ p) (positive⁻¹ q))
∣-∣-cong : p ≃ q → ∣ p ∣ ≃ ∣ q ∣
∣-∣-cong p@{mkℚᵘ +[1+ _ ] _} q@{mkℚᵘ +[1+ _ ] _} (*≡* ↥p↧q≡↥q↧p) = *≡* ↥p↧q≡↥q↧p
∣-∣-cong p@{mkℚᵘ +0 _} q@{mkℚᵘ +0 _} (*≡* ↥p↧q≡↥q↧p) = *≡* ↥p↧q≡↥q↧p
∣-∣-cong p@{mkℚᵘ -[1+ _ ] _} q@{mkℚᵘ +0 _} (*≡* ())
∣-∣-cong p@{mkℚᵘ -[1+ _ ] _} q@{mkℚᵘ -[1+ _ ] _} (*≡* ↥p↧q≡↥q↧p) = *≡* (begin
↥ ∣ p ∣ ℤ.* ↧ q ≡⟨ ℤ.neg-involutive _ ⟩
ℤ.- ℤ.- (↥ ∣ p ∣ ℤ.* ↧ q) ≡⟨ cong ℤ.-_ (ℤ.neg-distribˡ-* (↥ ∣ p ∣) (↧ q)) ⟩
ℤ.- (↥ p ℤ.* ↧ q) ≡⟨ cong ℤ.-_ ↥p↧q≡↥q↧p ⟩
ℤ.- (↥ q ℤ.* ↧ p) ≡⟨ cong ℤ.-_ (ℤ.neg-distribˡ-* (↥ ∣ q ∣) (↧ p)) ⟩
ℤ.- ℤ.- (↥ ∣ q ∣ ℤ.* ↧ p) ≡˘⟨ ℤ.neg-involutive _ ⟩
↥ ∣ q ∣ ℤ.* ↧ p ∎)
where open ≡-Reasoning
∣p∣≃0⇒p≃0 : ∣ p ∣ ≃ 0ℚᵘ → p ≃ 0ℚᵘ
∣p∣≃0⇒p≃0 {mkℚᵘ (ℤ.+ n) d-1} p≃0ℚ = p≃0ℚ
∣p∣≃0⇒p≃0 {mkℚᵘ -[1+ n ] d-1} (*≡* ())
0≤∣p∣ : ∀ p → 0ℚᵘ ≤ ∣ p ∣
0≤∣p∣ (mkℚᵘ +0 _) = *≤* (ℤ.+≤+ ℕ.z≤n)
0≤∣p∣ (mkℚᵘ +[1+ _ ] _) = *≤* (ℤ.+≤+ ℕ.z≤n)
0≤∣p∣ (mkℚᵘ -[1+ _ ] _) = *≤* (ℤ.+≤+ ℕ.z≤n)
∣-p∣≡∣p∣ : ∀ p → ∣ - p ∣ ≡ ∣ p ∣
∣-p∣≡∣p∣ (mkℚᵘ +[1+ n ] d) = refl
∣-p∣≡∣p∣ (mkℚᵘ +0 d) = refl
∣-p∣≡∣p∣ (mkℚᵘ -[1+ n ] d) = refl
∣-p∣≃∣p∣ : ∀ p → ∣ - p ∣ ≃ ∣ p ∣
∣-p∣≃∣p∣ = ≃-reflexive ∘ ∣-p∣≡∣p∣
0≤p⇒∣p∣≡p : 0ℚᵘ ≤ p → ∣ p ∣ ≡ p
0≤p⇒∣p∣≡p {mkℚᵘ (ℤ.+ n) d-1} 0≤p = refl
0≤p⇒∣p∣≡p {mkℚᵘ -[1+ n ] d-1} 0≤p = contradiction 0≤p (<⇒≱ (*<* ℤ.-<+))
0≤p⇒∣p∣≃p : 0ℚᵘ ≤ p → ∣ p ∣ ≃ p
0≤p⇒∣p∣≃p {p} = ≃-reflexive ∘ 0≤p⇒∣p∣≡p {p}
∣p∣≡p⇒0≤p : ∣ p ∣ ≡ p → 0ℚᵘ ≤ p
∣p∣≡p⇒0≤p {mkℚᵘ (ℤ.+ n) d-1} ∣p∣≡p = *≤* (begin
0ℤ ℤ.* +[1+ d-1 ] ≡⟨ ℤ.*-zeroˡ (ℤ.+ d-1) ⟩
0ℤ ≤⟨ ℤ.+≤+ ℕ.z≤n ⟩
ℤ.+ n ≡˘⟨ ℤ.*-identityʳ (ℤ.+ n) ⟩
ℤ.+ n ℤ.* 1ℤ ∎)
where open ℤ.≤-Reasoning
∣p∣≡p∨∣p∣≡-p : ∀ p → (∣ p ∣ ≡ p) ⊎ (∣ p ∣ ≡ - p)
∣p∣≡p∨∣p∣≡-p (mkℚᵘ (ℤ.+ n) d-1) = inj₁ refl
∣p∣≡p∨∣p∣≡-p (mkℚᵘ (-[1+ n ]) d-1) = inj₂ refl
∣p∣≃p⇒0≤p : ∣ p ∣ ≃ p → 0ℚᵘ ≤ p
∣p∣≃p⇒0≤p {p} ∣p∣≃p with ∣p∣≡p∨∣p∣≡-p p
... | inj₁ ∣p∣≡p = ∣p∣≡p⇒0≤p ∣p∣≡p
... | inj₂ ∣p∣≡-p rewrite ∣p∣≡-p = ≤-reflexive (≃-sym (p≃-p⇒p≃0 p (≃-sym ∣p∣≃p)))
∣p+q∣≤∣p∣+∣q∣ : ∀ p q → ∣ p + q ∣ ≤ ∣ p ∣ + ∣ q ∣
∣p+q∣≤∣p∣+∣q∣ p@record{} q@record{} = *≤* (begin
↥ ∣ p + q ∣ ℤ.* ↧ (∣ p ∣ + ∣ q ∣) ≡⟨⟩
↥ ∣ (↥p↧q ℤ.+ ↥q↧p) / ↧p↧q ∣ ℤ.* ℤ.+ ↧p↧q ≡⟨⟩
↥ (ℤ.+ ℤ.∣ ↥p↧q ℤ.+ ↥q↧p ∣ / ↧p↧q) ℤ.* ℤ.+ ↧p↧q ≡⟨ cong (ℤ._* ℤ.+ ↧p↧q) (↥[n/d]≡n (ℤ.+ ℤ.∣ ↥p↧q ℤ.+ ↥q↧p ∣) ↧p↧q) ⟩
ℤ.+ ℤ.∣ ↥p↧q ℤ.+ ↥q↧p ∣ ℤ.* ℤ.+ ↧p↧q ≤⟨ ℤ.*-monoʳ-≤-nonNeg (ℤ.+ ↧p↧q) (ℤ.+≤+ (ℤ.∣i+j∣≤∣i∣+∣j∣ ↥p↧q ↥q↧p)) ⟩
(ℤ.+ ℤ.∣ ↥p↧q ∣ ℤ.+ ℤ.+ ℤ.∣ ↥q↧p ∣) ℤ.* ℤ.+ ↧p↧q ≡˘⟨ cong₂ (λ h₁ h₂ → (h₁ ℤ.+ h₂) ℤ.* ℤ.+ ↧p↧q) ∣↥p∣↧q≡∣↥p↧q∣ ∣↥q∣↧p≡∣↥q↧p∣ ⟩
(∣↥p∣↧q ℤ.+ ∣↥q∣↧p) ℤ.* ℤ.+ ↧p↧q ≡⟨⟩
(↥∣p∣↧q ℤ.+ ↥∣q∣↧p) ℤ.* ℤ.+ ↧p↧q ≡⟨ cong (ℤ._* ℤ.+ ↧p↧q) (↥[n/d]≡n (↥∣p∣↧q ℤ.+ ↥∣q∣↧p) ↧p↧q) ⟩
↥ ((↥∣p∣↧q ℤ.+ ↥∣q∣↧p) / ↧p↧q) ℤ.* ℤ.+ ↧p↧q ≡⟨⟩
↥ (∣ p ∣ + ∣ q ∣) ℤ.* ↧ ∣ p + q ∣ ∎)
where
open ℤ.≤-Reasoning
↥p↧q = ↥ p ℤ.* ↧ q
↥q↧p = ↥ q ℤ.* ↧ p
↥∣p∣↧q = ↥ ∣ p ∣ ℤ.* ↧ q
↥∣q∣↧p = ↥ ∣ q ∣ ℤ.* ↧ p
∣↥p∣↧q = ℤ.+ ℤ.∣ ↥ p ∣ ℤ.* ↧ q
∣↥q∣↧p = ℤ.+ ℤ.∣ ↥ q ∣ ℤ.* ↧ p
↧p↧q = ↧ₙ p ℕ.* ↧ₙ q
∣m∣n≡∣mn∣ : ∀ m n → ℤ.+ ℤ.∣ m ∣ ℤ.* ℤ.+ n ≡ ℤ.+ ℤ.∣ m ℤ.* ℤ.+ n ∣
∣m∣n≡∣mn∣ m n = begin-equality
ℤ.+ ℤ.∣ m ∣ ℤ.* ℤ.+ n ≡⟨⟩
ℤ.+ ℤ.∣ m ∣ ℤ.* ℤ.+ ℤ.∣ ℤ.+ n ∣ ≡⟨ ℤ.pos-distrib-* ℤ.∣ m ∣ ℤ.∣ ℤ.+ n ∣ ⟩
ℤ.+ (ℤ.∣ m ∣ ℕ.* n) ≡⟨⟩
ℤ.+ (ℤ.∣ m ∣ ℕ.* ℤ.∣ ℤ.+ n ∣) ≡˘⟨ cong ℤ.+_ (ℤ.∣i*j∣≡∣i∣*∣j∣ m (ℤ.+ n)) ⟩
ℤ.+ (ℤ.∣ m ℤ.* ℤ.+ n ∣) ∎
∣↥p∣↧q≡∣↥p↧q∣ : ∣↥p∣↧q ≡ ℤ.+ ℤ.∣ ↥p↧q ∣
∣↥p∣↧q≡∣↥p↧q∣ = ∣m∣n≡∣mn∣ (↥ p) (↧ₙ q)
∣↥q∣↧p≡∣↥q↧p∣ : ∣↥q∣↧p ≡ ℤ.+ ℤ.∣ ↥q↧p ∣
∣↥q∣↧p≡∣↥q↧p∣ = ∣m∣n≡∣mn∣ (↥ q) (↧ₙ p)
∣p-q∣≤∣p∣+∣q∣ : ∀ p q → ∣ p - q ∣ ≤ ∣ p ∣ + ∣ q ∣
∣p-q∣≤∣p∣+∣q∣ p q = begin
∣ p - q ∣ ≤⟨ ∣p+q∣≤∣p∣+∣q∣ p (- q) ⟩
∣ p ∣ + ∣ - q ∣ ≡⟨ cong (∣ p ∣ +_) (∣-p∣≡∣p∣ q) ⟩
∣ p ∣ + ∣ q ∣ ∎
where open ≤-Reasoning
∣p*q∣≡∣p∣*∣q∣ : ∀ p q → ∣ p * q ∣ ≡ ∣ p ∣ * ∣ q ∣
∣p*q∣≡∣p∣*∣q∣ p@record{} q@record{} = begin
∣ p * q ∣ ≡⟨⟩
∣ (↥ p ℤ.* ↥ q) / (↧ₙ p ℕ.* ↧ₙ q) ∣ ≡⟨⟩
ℤ.+ ℤ.∣ ↥ p ℤ.* ↥ q ∣ / (↧ₙ p ℕ.* ↧ₙ q) ≡⟨ cong (λ h → ℤ.+ h / ((↧ₙ p) ℕ.* (↧ₙ q))) (ℤ.∣i*j∣≡∣i∣*∣j∣ (↥ p) (↥ q)) ⟩
ℤ.+ (ℤ.∣ ↥ p ∣ ℕ.* ℤ.∣ ↥ q ∣) / (↧ₙ p ℕ.* ↧ₙ q) ≡˘⟨ cong (_/ (↧ₙ p ℕ.* ↧ₙ q)) (ℤ.pos-distrib-* ℤ.∣ ↥ p ∣ ℤ.∣ ↥ q ∣) ⟩
(ℤ.+ ℤ.∣ ↥ p ∣ ℤ.* ℤ.+ ℤ.∣ ↥ q ∣) / (↧ₙ p ℕ.* ↧ₙ q) ≡⟨⟩
(ℤ.+ ℤ.∣ ↥ p ∣ / ↧ₙ p) * (ℤ.+ ℤ.∣ ↥ q ∣ / ↧ₙ q) ≡⟨⟩
∣ p ∣ * ∣ q ∣ ∎
where open ≡-Reasoning
∣p*q∣≃∣p∣*∣q∣ : ∀ p q → ∣ p * q ∣ ≃ ∣ p ∣ * ∣ q ∣
∣p*q∣≃∣p∣*∣q∣ p q = ≃-reflexive (∣p*q∣≡∣p∣*∣q∣ p q)
∣∣p∣∣≡∣p∣ : ∀ p → ∣ ∣ p ∣ ∣ ≡ ∣ p ∣
∣∣p∣∣≡∣p∣ p = 0≤p⇒∣p∣≡p (0≤∣p∣ p)
∣∣p∣∣≃∣p∣ : ∀ p → ∣ ∣ p ∣ ∣ ≃ ∣ p ∣
∣∣p∣∣≃∣p∣ p = ≃-reflexive (∣∣p∣∣≡∣p∣ p)
∣-∣-nonNeg : ∀ p → NonNegative ∣ p ∣
∣-∣-nonNeg (mkℚᵘ +[1+ _ ] _) = _
∣-∣-nonNeg (mkℚᵘ +0 _) = _
∣-∣-nonNeg (mkℚᵘ -[1+ _ ] _) = _
neg-mono-<-> = neg-mono-<
{-# WARNING_ON_USAGE neg-mono-<->
"Warning: neg-mono-<-> was deprecated in v1.5.
Please use neg-mono-< instead."
#-}
↥[p/q]≡p = ↥[n/d]≡n
{-# WARNING_ON_USAGE ↥[p/q]≡p
"Warning: ↥[p/q]≡p was deprecated in v2.0.
Please use ↥[n/d]≡n instead."
#-}
↧[p/q]≡q = ↧[n/d]≡d
{-# WARNING_ON_USAGE ↧[p/q]≡q
"Warning: ↧[p/q]≡q was deprecated in v2.0.
Please use ↧[n/d]≡d instead."
#-}
*-monoʳ-≤-pos : ∀ {r} → Positive r → (r *_) Preserves _≤_ ⟶ _≤_
*-monoʳ-≤-pos r@{mkℚᵘ +[1+ _ ] _} _ = *-monoʳ-≤-nonNeg r
{-# WARNING_ON_USAGE *-monoʳ-≤-pos
"Warning: *-monoʳ-≤-pos was deprecated in v2.0.
Please use *-monoʳ-≤-nonNeg instead."
#-}
*-monoˡ-≤-pos : ∀ {r} → Positive r → (_* r) Preserves _≤_ ⟶ _≤_
*-monoˡ-≤-pos r@{mkℚᵘ +[1+ _ ] _} _ = *-monoˡ-≤-nonNeg r
{-# WARNING_ON_USAGE *-monoˡ-≤-pos
"Warning: *-monoˡ-≤-nonNeg was deprecated in v2.0.
Please use *-monoˡ-≤-nonNeg instead."
#-}
*-monoˡ-≤-neg : ∀ r → Negative r → (_* r) Preserves _≤_ ⟶ _≥_
*-monoˡ-≤-neg r@(mkℚᵘ -[1+ _ ] _) _ = *-monoˡ-≤-nonPos r
{-# WARNING_ON_USAGE *-monoˡ-≤-neg
"Warning: *-monoˡ-≤-neg was deprecated in v2.0.
Please use *-monoˡ-≤-nonPos instead."
#-}
*-monoʳ-≤-neg : ∀ r → Negative r → (r *_) Preserves _≤_ ⟶ _≥_
*-monoʳ-≤-neg r@(mkℚᵘ -[1+ _ ] _) _ = *-monoʳ-≤-nonPos r
{-# WARNING_ON_USAGE *-monoʳ-≤-neg
"Warning: *-monoʳ-≤-neg was deprecated in v2.0.
Please use *-monoʳ-≤-nonPos instead."
#-}
*-cancelˡ-<-pos : ∀ r → Positive r → ∀ {p q} → r * p < r * q → p < q
*-cancelˡ-<-pos r@(mkℚᵘ +[1+ _ ] _) r>0 = *-cancelˡ-<-nonNeg r
{-# WARNING_ON_USAGE *-cancelˡ-<-pos
"Warning: *-cancelˡ-<-pos was deprecated in v2.0.
Please use *-cancelˡ-<-nonNeg instead."
#-}
*-cancelʳ-<-pos : ∀ r → Positive r → ∀ {p q} → p * r < q * r → p < q
*-cancelʳ-<-pos r@(mkℚᵘ +[1+ _ ] _) r>0 = *-cancelʳ-<-nonNeg r
{-# WARNING_ON_USAGE *-cancelʳ-<-pos
"Warning: *-cancelʳ-<-pos was deprecated in v2.0.
Please use *-cancelʳ-<-nonNeg instead."
#-}
*-cancelˡ-<-neg : ∀ r → Negative r → ∀ {p q} → r * p < r * q → q < p
*-cancelˡ-<-neg r@(mkℚᵘ -[1+ _ ] _) _ = *-cancelˡ-<-nonPos r
{-# WARNING_ON_USAGE *-cancelˡ-<-neg
"Warning: *-cancelˡ-<-neg was deprecated in v2.0.
Please use *-cancelˡ-<-nonPos instead."
#-}
*-cancelʳ-<-neg : ∀ r → Negative r → ∀ {p q} → p * r < q * r → q < p
*-cancelʳ-<-neg r@(mkℚᵘ -[1+ _ ] _) _ = *-cancelʳ-<-nonPos r
{-# WARNING_ON_USAGE *-cancelʳ-<-neg
"Warning: *-cancelʳ-<-neg was deprecated in v2.0.
Please use *-cancelʳ-<-nonPos instead."
#-}
positive⇒nonNegative : ∀ {p} → Positive p → NonNegative p
positive⇒nonNegative {p} p>0 = pos⇒nonNeg p {{p>0}}
{-# WARNING_ON_USAGE positive⇒nonNegative
"Warning: positive⇒nonNegative was deprecated in v2.0.
Please use pos⇒nonNeg instead."
#-}
negative⇒nonPositive : ∀ {p} → Negative p → NonPositive p
negative⇒nonPositive {p} p<0 = neg⇒nonPos p {{p<0}}
{-# WARNING_ON_USAGE negative⇒nonPositive
"Warning: negative⇒nonPositive was deprecated in v2.0.
Please use neg⇒nonPos instead."
#-}
negative<positive : ∀ {p q} → .(Negative p) → .(Positive q) → p < q
negative<positive {p} {q} p<0 q>0 = neg<pos p q {{p<0}} {{q>0}}
{-# WARNING_ON_USAGE negative<positive
"Warning: negative<positive was deprecated in v2.0.
Please use neg<pos instead."
#-}