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Use records rather than nested pairs to represent 'fixed height'

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Signed-off-by: Danila Fedorin <danila.fedorin@gmail.com>
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Danila Fedorin
2024-05-09 20:11:04 -07:00
parent 95669b2c65
commit 16fa4cd1d8
8 changed files with 62 additions and 39 deletions
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32
Lattice/Prod.agda
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@@ -143,17 +143,8 @@ module _ (≈₁-dec : IsDecidable _≈₁_) (≈₂-dec : IsDecidable _≈₂_)
∙,b-Preserves-≈₁ : ∀ (b : B) → (λ a → (a , b)) Preserves _≈₁_ ⟶ _≈_
∙,b-Preserves-≈₁ b {a₁} {a₂} a₁≈a₂ = (a₁≈a₂ , ≈₂-refl)
⊥₁ : A
⊥₁ = proj₁ (proj₁ (proj₁ fhA))
⊤₁ : A
⊤₁ = proj₂ (proj₁ (proj₁ fhA))
⊥₂ : B
⊥₂ = proj₁ (proj₁ (proj₁ fhB))
⊤₂ : B
⊤₂ = proj₂ (proj₁ (proj₁ fhB))
open ChainA.Height fhA using () renaming (⊥ to ⊥₁; ⊤ to ⊤₁; longestChain to longestChain₁; bounded to bounded₁)
open ChainB.Height fhB using () renaming (⊥ to ⊥₂; ⊤ to ⊤₂; longestChain to longestChain₂; bounded to bounded₂)
unzip : ∀ {a₁ a₂ : A} {b₁ b₂ : B} {n : ℕ} → Chain (a₁ , b₁) (a₂ , b₂) n → Σ (ℕ × ℕ) (λ (n₁ , n₂) → ((Chain₁ a₁ a₂ n₁ × Chain₂ b₁ b₂ n₂) × (n ≤ n₁ + n₂)))
unzip (done (a₁≈a₂ , b₁≈b₂)) = ((0 , 0) , ((done₁ a₁≈a₂ , done₂ b₁≈b₂) , ≤-refl))
@@ -172,15 +163,16 @@ module _ (≈₁-dec : IsDecidable _≈₁_) (≈₂-dec : IsDecidable _≈₂_)
))
fixedHeight : IsLattice.FixedHeight isLattice (h₁ + h₂)
fixedHeight =
( ( ((⊥₁ , ⊥₂) , (⊤₁ , ⊤₂))
, concat
(ChainMapping₁.Chain-map (λ a → (a , ⊥₂)) (∙,b-Monotonic _) proj₁ (∙,b-Preserves-≈₁ _) (proj₂ (proj₁ fhA)))
(ChainMapping₂.Chain-map (λ b → (⊤₁ , b)) (a,∙-Monotonic _) proj₂ (a,∙-Preserves-≈₂ _) (proj₂ (proj₁ fhB)))
)
, λ a₁b₁a₂b₂ → let ((n₁ , n₂) , ((a₁a₂ , b₁b₂) , n≤n₁+n₂)) = unzip a₁b₁a₂b₂
in ≤-trans n≤n₁+n₂ (+-mono-≤ (proj₂ fhA a₁a₂) (proj₂ fhB b₁b₂))
)
fixedHeight = record
{ ⊥ = (⊥₁ , ⊥₂)
; ⊤ = (⊤₁ , ⊤₂)
; longestChain = concat
(ChainMapping₁.Chain-map (λ a → (a , ⊥₂)) (∙,b-Monotonic _) proj₁ (∙,b-Preserves-≈₁ _) longestChain₁)
(ChainMapping₂.Chain-map (λ b → (⊤₁ , b)) (a,∙-Monotonic _) proj₂ (a,∙-Preserves-≈₂ _) longestChain₂)
; bounded = λ a₁b₁a₂b₂ →
let ((n₁ , n₂) , ((a₁a₂ , b₁b₂) , n≤n₁+n₂)) = unzip a₁b₁a₂b₂
in ≤-trans n≤n₁+n₂ (+-mono-≤ (bounded₁ a₁a₂) (bounded₂ b₁b₂))
}
isFiniteHeightLattice : IsFiniteHeightLattice (A × B) (h₁ + h₂) _≈_ _⊔_ _⊓_
isFiniteHeightLattice = record