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punchOut preserves ordering #1913

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Feb 20, 2023
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5 changes: 5 additions & 0 deletions CHANGELOG.md
Original file line number Diff line number Diff line change
Expand Up @@ -1790,6 +1790,11 @@ Other minor changes

ℕ-ℕ≡toℕ‿ℕ- : n ℕ-ℕ i ≡ toℕ (n ℕ- i)

punchIn-mono-≤ : ∀ i (j k : Fin n) → j ≤ k → punchIn i j ≤ punchIn i k
punchIn-cancel-≤ : ∀ i (j k : Fin n) → punchIn i j ≤ punchIn i k → j ≤ k
punchOut-mono-≤ : (i≢j : i ≢ j) (i≢k : i ≢ k) → j ≤ k → punchOut i≢j ≤ punchOut i≢k
punchOut-cancel-≤ : (i≢j : i ≢ j) (i≢k : i ≢ k) → punchOut i≢j ≤ punchOut i≢k → j ≤ k

lower₁-injective : lower₁ i n≢i ≡ lower₁ j n≢j → i ≡ j
pinch-injective : suc i ≢ j → suc i ≢ k → pinch i j ≡ pinch i k → j ≡ k

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26 changes: 26 additions & 0 deletions src/Data/Fin/Properties.agda
Original file line number Diff line number Diff line change
Expand Up @@ -802,6 +802,16 @@ punchIn-injective (suc i) (suc j) (suc k) ↑j+1≡↑k+1 =
punchInᵢ≢i : ∀ i (j : Fin n) → punchIn i j ≢ i
punchInᵢ≢i (suc i) (suc j) = punchInᵢ≢i i j ∘ suc-injective

punchIn-mono-≤ : ∀ i (j k : Fin n) → j ≤ k → punchIn i j ≤ punchIn i k
punchIn-mono-≤ zero _ _ j≤k = s≤s j≤k
punchIn-mono-≤ (suc _) zero _ z≤n = z≤n
punchIn-mono-≤ (suc i) (suc j) (suc k) (s≤s j≤k) = s≤s (punchIn-mono-≤ i j k j≤k)

punchIn-cancel-≤ : ∀ i (j k : Fin n) → punchIn i j ≤ punchIn i k → j ≤ k
punchIn-cancel-≤ zero _ _ (s≤s j≤k) = j≤k
punchIn-cancel-≤ (suc _) zero _ z≤n = z≤n
punchIn-cancel-≤ (suc i) (suc j) (suc k) (s≤s ↑j≤↑k) = s≤s (punchIn-cancel-≤ i j k ↑j≤↑k)

------------------------------------------------------------------------
-- punchOut
------------------------------------------------------------------------
Expand Down Expand Up @@ -835,6 +845,22 @@ punchOut-injective {suc n} {suc i} {zero} {zero} _ _ _ = refl
punchOut-injective {suc n} {suc i} {suc j} {suc k} i≢j i≢k pⱼ≡pₖ =
cong suc (punchOut-injective (i≢j ∘ cong suc) (i≢k ∘ cong suc) (suc-injective pⱼ≡pₖ))

punchOut-mono-≤ : ∀ {i j k : Fin (suc n)} (i≢j : i ≢ j) (i≢k : i ≢ k) →
j ≤ k → punchOut i≢j ≤ punchOut i≢k
punchOut-mono-≤ {_ } {zero } {zero } {_ } 0≢0 _ z≤n = contradiction refl 0≢0
punchOut-mono-≤ {_ } {zero } {suc _} {suc _} _ _ (s≤s j≤k) = j≤k
punchOut-mono-≤ {suc _} {suc _} {zero } {_ } _ _ z≤n = z≤n
punchOut-mono-≤ {suc _} {suc _} {suc _} {suc _} i≢j i≢k (s≤s j≤k) = s≤s (punchOut-mono-≤ (i≢j ∘ cong suc) (i≢k ∘ cong suc) j≤k)

punchOut-cancel-≤ : ∀ {i j k : Fin (suc n)} (i≢j : i ≢ j) (i≢k : i ≢ k) →
punchOut i≢j ≤ punchOut i≢k → j ≤ k
punchOut-cancel-≤ {_ } {zero } {zero } {_ } 0≢0 _ _ = contradiction refl 0≢0
punchOut-cancel-≤ {_ } {zero } {suc _} {zero } _ 0≢0 _ = contradiction refl 0≢0
punchOut-cancel-≤ {suc _} {zero } {suc _} {suc _} _ _ pⱼ≤pₖ = s≤s pⱼ≤pₖ
punchOut-cancel-≤ {_ } {suc _} {zero } {_ } _ _ _ = z≤n
punchOut-cancel-≤ {suc _} {suc _} {suc _} {zero } _ _ ()
punchOut-cancel-≤ {suc _} {suc _} {suc _} {suc _} i≢j i≢k (s≤s pⱼ≤pₖ) = s≤s (punchOut-cancel-≤ (i≢j ∘ cong suc) (i≢k ∘ cong suc) pⱼ≤pₖ)

punchIn-punchOut : ∀ {i j : Fin (suc n)} (i≢j : i ≢ j) →
punchIn i (punchOut i≢j) ≡ j
punchIn-punchOut {_} {zero} {zero} 0≢0 = contradiction refl 0≢0
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