changeset 256:5aff0067b194

...
author Shinji KONO <kono@ie.u-ryukyu.ac.jp>
date Mon, 05 Jul 2021 11:10:15 +0900
parents 4e4e148eb7e5
children 246da8456ad1
files automaton-in-agda/src/bijection.agda
diffstat 1 files changed, 226 insertions(+), 2 deletions(-) [+]
line wrap: on
line diff
--- a/automaton-in-agda/src/bijection.agda	Thu Jul 01 19:07:19 2021 +0900
+++ b/automaton-in-agda/src/bijection.agda	Mon Jul 05 11:10:15 2021 +0900
@@ -3,16 +3,17 @@
 open import Level renaming ( zero to Zero ; suc to Suc )
 open import Data.Nat
 open import Data.Maybe
-open import Data.List hiding ([_])
+open import Data.List hiding ([_] ; sum )
 open import Data.Nat.Properties
 open import Relation.Nullary
 open import Data.Empty
-open import Data.Unit
+open import Data.Unit hiding ( _≤_ )
 open import  Relation.Binary.Core hiding (_⇔_)
 open import  Relation.Binary.Definitions
 open import Relation.Binary.PropositionalEquality
 
 open import logic
+open import nat
 
 record Bijection {n m : Level} (R : Set n) (S : Set m) : Set (n Level.⊔ m)  where
    field
@@ -60,6 +61,229 @@
            diag b n 
         ∎ ) where open ≡-Reasoning
 
+
+open _∧_
+
+record NN ( i  : ℕ) (nxn→n :  ℕ →  ℕ → ℕ) (n→nxn : ℕ → ℕ ∧ ℕ) : Set where
+  field
+     j k sum stage : ℕ
+     nn : j + k ≡ sum
+     ni : i ≡ j + stage 
+     k1 : nxn→n j k ≡ i
+     k0 : n→nxn i ≡ ⟪ j , k ⟫ 
+     nn-unique : {j0 k0 : ℕ } →  nxn→n j0 k0 ≡ i  → ⟪ j , k ⟫ ≡ ⟪ j0 , k0 ⟫ 
+
+i≤0→i≡0 : {i : ℕ } → i ≤ 0 → i ≡ 0
+i≤0→i≡0 {0} z≤n = refl
+
+
+nxn : Bijection ℕ (ℕ ∧ ℕ)
+nxn = record {
+     fun← = λ p → nxn→n (proj1 p) (proj2 p)
+   ; fun→ =  n→nxn 
+   ; fiso← = n-id
+   ; fiso→ = λ x → nn-id (proj1 x) (proj2 x)
+  } where
+     nxn→n :  ℕ →  ℕ → ℕ
+     nxn→n zero zero = zero
+     nxn→n zero (suc j) = j + suc (nxn→n zero j)
+     nxn→n (suc i) zero = suc i + suc (nxn→n i zero)
+     nxn→n (suc i) (suc j) = suc i + suc j + suc (nxn→n i (suc j))
+     n→nxn : ℕ → ℕ ∧ ℕ
+     n→nxn zero = ⟪ 0 , 0 ⟫
+     n→nxn (suc i) with n→nxn i
+     ... | ⟪ x , zero ⟫ = ⟪ zero  , suc x ⟫
+     ... | ⟪ x , suc y ⟫ = ⟪ suc x , y ⟫
+
+     nxn→n0 : { j k : ℕ } →  nxn→n j k ≡ 0 → ( j ≡ 0 ) ∧ ( k ≡ 0 )
+     nxn→n0 {zero} {zero} eq = ⟪ refl , refl ⟫
+     nxn→n0 {zero} {(suc k)} eq = ⊥-elim ( nat-≡< (sym eq) (subst (λ k → 0 < k) (+-comm _ k) (s≤s z≤n)))
+     nxn→n0 {(suc j)} {zero} eq = ⊥-elim ( nat-≡< (sym eq) (s≤s z≤n) )
+     nxn→n0 {(suc j)} {(suc k)} eq = ⊥-elim ( nat-≡< (sym eq) (s≤s z≤n) )
+
+     nid20 : (i : ℕ) →  i +  (nxn→n 0 i) ≡ nxn→n i 0
+     nid20 zero = refl -- suc (i + (i + suc (nxn→n 0 i))) ≡ suc (i + suc (nxn→n i 0))
+     nid20 (suc i) = begin
+         suc (i + (i + suc (nxn→n 0 i)))  ≡⟨ cong (λ k → suc (i + k)) (sym (+-assoc i 1 (nxn→n 0 i))) ⟩
+         suc (i + ((i + 1) + nxn→n 0 i))  ≡⟨ cong (λ k →  suc (i + (k + nxn→n 0 i))) (+-comm i 1)  ⟩
+         suc (i + suc (i + nxn→n 0 i)) ≡⟨ cong ( λ k → suc (i + suc k)) (nid20 i)  ⟩
+         suc (i + suc (nxn→n i 0)) ∎  where open ≡-Reasoning
+
+     nid4 : {i j : ℕ} →  i + 1 + j ≡ i + suc j
+     nid4 {zero} {j} = refl
+     nid4 {suc i} {j} = cong suc (nid4 {i} {j} )
+     nid5 : {i j k : ℕ} →  i + suc (suc j) + suc k ≡ i + suc j + suc (suc k )
+     nid5 {zero} {j} {k} = begin
+          suc (suc j) + suc k ≡⟨ +-assoc 1 (suc j) _ ⟩
+          1 + (suc j + suc k) ≡⟨ +-comm 1 _ ⟩
+          (suc j + suc k) + 1 ≡⟨ +-assoc (suc j) (suc k) _ ⟩
+          suc j + (suc k + 1) ≡⟨ cong (λ k → suc j + k ) (+-comm (suc k) 1) ⟩
+          suc j + suc (suc k) ∎ where open ≡-Reasoning
+     nid5 {suc i} {j} {k} = cong suc (nid5 {i} {j} {k} )
+
+     nid2 : (i j : ℕ) → suc (nxn→n i (suc j)) ≡ nxn→n (suc i) j 
+     nid2 zero zero = refl
+     nid2 zero (suc j) = refl
+     nid2 (suc i) zero = begin
+          suc (nxn→n (suc i) 1)  ≡⟨ refl ⟩
+          suc (suc (i + 1 + suc (nxn→n i 1)))  ≡⟨ cong (λ k → suc (suc k)) nid4  ⟩
+          suc (suc (i + suc (suc (nxn→n i 1))))  ≡⟨ cong (λ k →  suc (suc (i + suc (suc k)))) (nid3 i) ⟩
+          suc (suc (i + suc (suc (i + suc (nxn→n i 0)))))  ≡⟨ refl ⟩
+          nxn→n (suc (suc i)) zero ∎ where
+             open ≡-Reasoning
+             nid3 : (i : ℕ) → nxn→n i 1 ≡ i + suc (nxn→n i 0)
+             nid3 zero = refl
+             nid3 (suc i) = begin
+                 suc (i + 1 + suc (nxn→n i 1)) ≡⟨ cong suc nid4 ⟩
+                 suc (i + suc (suc (nxn→n i 1))) ≡⟨ cong (λ k →  suc (i + suc (suc k))) (nid3 i) ⟩
+                 suc (i + suc (suc (i + suc (nxn→n i 0))))
+              ∎
+     nid2 (suc i) (suc j) = begin
+          suc (nxn→n (suc i) (suc (suc j)))  ≡⟨ refl ⟩
+          suc (suc (i + suc (suc j) + suc (nxn→n i (suc (suc j)))))  ≡⟨ cong (λ k → suc (suc (i + suc (suc j) + k))) (nid2 i (suc j)) ⟩
+          suc (suc (i + suc (suc j) + suc      (i + suc j + suc (nxn→n i (suc j)))))  ≡⟨ cong ( λ k → suc (suc k)) nid5 ⟩
+          suc (suc (i + suc j       + suc (suc (i + suc j + suc (nxn→n i (suc j)))))) ≡⟨ refl ⟩
+          nxn→n (suc (suc i)) (suc j) ∎ where
+             open ≡-Reasoning
+
+     nid00 : (i : ℕ) → suc (nxn→n i 0) ≡ nxn→n 0 (suc i) 
+     nid00 zero = refl
+     nid00 (suc i) = begin
+        suc (suc (i + suc (nxn→n i 0))) ≡⟨ cong (λ k → suc (suc (i + k ))) (nid00 i) ⟩
+        suc (suc (i + (nxn→n 0 (suc i)))) ≡⟨ refl ⟩
+        suc (suc (i + (i + suc (nxn→n 0 i))))  ≡⟨ cong suc (sym ( +-assoc 1 i (i + suc (nxn→n 0 i)))) ⟩
+        suc ((1 + i) + (i + suc (nxn→n 0 i))) ≡⟨ cong (λ k → suc (k + (i + suc (nxn→n 0 i)))) (+-comm 1 i) ⟩
+        suc ((i + 1) + (i + suc (nxn→n 0 i))) ≡⟨ cong suc (+-assoc i 1 (i + suc (nxn→n 0 i))) ⟩
+        suc (i + suc (i + suc (nxn→n 0 i))) ∎ where open ≡-Reasoning
+
+     nn : ( i  : ℕ) → NN i nxn→n n→nxn
+     nn zero = record { j = 0 ; k = 0 ; sum = 0 ; stage = 0 ; nn = refl ; ni = refl ; k1 = refl ; k0 = refl
+        ;  nn-unique = λ {j0} {k0} eq → cong₂ (λ x y → ⟪ x , y ⟫) (sym (proj1 (nxn→n0 eq))) (sym (proj2 (nxn→n0 {j0} {k0} eq))) }
+     nn (suc i) with NN.k (nn i)  | inspect  NN.k (nn i) 
+     ... | zero | record { eq = eq } = record { k = suc (NN.sum (nn i)) ; j = 0 ; sum = suc  (NN.sum (nn i)) ; stage = suc  (NN.sum (nn i)) + (NN.stage (nn i))
+         ; nn = refl
+         ; ni = nn01 ; k1 = nn02 ; k0 = nn03 ;  nn-unique = nn04 } where
+            sum = NN.sum (nn i)
+            stage = NN.stage (nn i)
+            j = NN.j (nn i)
+            nn01 : suc i ≡ 0 + (suc sum + stage )
+            nn01 = begin
+               suc i ≡⟨ cong suc (NN.ni (nn i)) ⟩
+               suc ((NN.j  (nn i) ) + stage )  ≡⟨ cong (λ k → suc (k + stage )) (+-comm 0 _ ) ⟩
+               suc ((NN.j  (nn i) + 0 ) + stage )  ≡⟨ cong (λ k → suc ((NN.j  (nn i) + k) + stage )) (sym eq) ⟩
+               suc ((NN.j (nn i) + NN.k  (nn i)) + stage )  ≡⟨ cong (λ k → suc ( k + stage )) (NN.nn (nn i)) ⟩
+               0 +   (suc sum + stage ) ∎  where open ≡-Reasoning
+            nn02 :  nxn→n 0 (suc sum)  ≡ suc i
+            nn02 = begin
+               sum + suc (nxn→n 0 sum) ≡⟨ sym (+-assoc sum 1 (nxn→n 0 sum)) ⟩
+               (sum + 1) + nxn→n 0 sum  ≡⟨ cong (λ k → k + nxn→n 0 sum )  (+-comm sum 1 )⟩
+               suc (sum + nxn→n 0 sum) ≡⟨ cong suc (nid20 sum ) ⟩
+               suc (nxn→n sum 0) ≡⟨ cong (λ k → suc (nxn→n k 0 )) (sym (NN.nn (nn i))) ⟩
+               suc (nxn→n (NN.j (nn i) + (NN.k (nn i))  ) 0) ≡⟨ cong₂ (λ j k → suc (nxn→n (NN.j (nn i) + j) k )) eq (sym eq)  ⟩
+               suc (nxn→n (NN.j (nn i) + 0 ) (NN.k (nn i))) ≡⟨ cong (λ k → suc ( nxn→n k (NN.k (nn i)))) (+-comm (NN.j (nn i)) 0) ⟩
+               suc (nxn→n (NN.j (nn i)) (NN.k (nn i))) ≡⟨ cong suc (NN.k1 (nn i) ) ⟩
+               suc i ∎  where open ≡-Reasoning
+            nn03 :  n→nxn (suc i) ≡ ⟪ 0 , suc (NN.sum (nn i)) ⟫   -- k0 : n→nxn i ≡ ⟪ NN.j (nn i) = sum , NN.k (nn i) = 0 ⟫
+            nn03 with n→nxn i | inspect  n→nxn i
+            ... | ⟪ x , zero  ⟫ | record { eq = eq1 } = begin
+                ⟪ zero , suc x ⟫ ≡⟨ cong (λ k →  ⟪ zero , suc k ⟫) (sym (cong proj1 eq1)) ⟩
+                ⟪ zero , suc (proj1 (n→nxn i)) ⟫ ≡⟨ cong (λ k →  ⟪ zero , suc k ⟫) (cong proj1 (NN.k0 (nn i)))  ⟩
+                ⟪ zero , suc (NN.j (nn i)) ⟫ ≡⟨  cong (λ k →  ⟪ zero , suc k ⟫) (+-comm 0 _ ) ⟩
+                ⟪ zero , suc (NN.j (nn i) + 0) ⟫ ≡⟨  cong (λ k →  ⟪ zero , suc (NN.j (nn i) + k)  ⟫ ) (sym eq)  ⟩
+                ⟪ zero , suc (NN.j (nn i) + NN.k (nn i)) ⟫ ≡⟨ cong (λ k →  ⟪ zero , suc k ⟫ ) (NN.nn (nn i))  ⟩
+                ⟪ 0 , suc sum  ⟫  ∎  where open ≡-Reasoning
+            ... | ⟪ x , suc y ⟫ | record { eq = eq1 } = ⊥-elim ( nat-≡< (sym (cong proj2 (NN.k0 (nn i)))) (begin
+               suc (NN.k (nn i)) ≡⟨ cong suc eq ⟩
+               suc 0 ≤⟨ s≤s z≤n  ⟩
+               suc y ≡⟨ sym (cong proj2 eq1) ⟩
+               proj2 (n→nxn i)  ∎ ))  where open ≤-Reasoning
+            --  nid2  : (i j : ℕ) → suc (nxn→n i (suc j)) ≡ nxn→n (suc i) j 
+            nn04 : {j0 k0 : ℕ} → nxn→n j0 k0 ≡ suc i → ⟪ 0 , suc (NN.sum (nn i)) ⟫ ≡ ⟪ j0 , k0 ⟫
+            nn04 {zero} {suc k0} eq1 = cong (λ k → ⟪ 0 , k ⟫ ) (cong suc (sym nn08)) where -- eq : nxn→n zero (suc k0) ≡ suc i -- 
+               nn07 : nxn→n k0 0 ≡ i
+               nn07 = cong pred ( begin
+                  suc ( nxn→n k0 0 ) ≡⟨ nid00 k0 ⟩
+                  nxn→n 0 (suc k0 )  ≡⟨ eq1 ⟩
+                  suc i  ∎ )  where open ≡-Reasoning 
+               nn08 : k0 ≡ sum 
+               nn08 = begin
+                  k0  ≡⟨ cong proj1 (sym (NN.nn-unique (nn i) nn07)) ⟩
+                  NN.j (nn i)  ≡⟨ +-comm 0 _ ⟩
+                  NN.j (nn i) + 0  ≡⟨ cong (λ k →  NN.j (nn i) + k) (sym eq) ⟩
+                  NN.j (nn i) + NN.k (nn i)  ≡⟨ NN.nn (nn i) ⟩
+                  sum   ∎   where open ≡-Reasoning 
+            nn04 {suc j0} {k0} eq1 = ⊥-elim ( nat-≡< (cong proj2 (nn06 nn05)) (subst (λ k → k < suc k0) (sym eq) (s≤s z≤n))) where
+               nn05 : nxn→n j0 (suc k0) ≡ i
+               nn05 = begin
+                  nxn→n j0 (suc k0)  ≡⟨ cong pred ( begin 
+                    suc (nxn→n j0 (suc k0))  ≡⟨ nid2 j0 k0 ⟩
+                    nxn→n (suc j0) k0  ≡⟨ eq1 ⟩
+                    suc i ∎ ) ⟩
+                  i ∎   where open ≡-Reasoning 
+               nn06 : nxn→n j0 (suc k0) ≡ i → ⟪ NN.j (nn i) , NN.k (nn i) ⟫ ≡ ⟪ j0 , suc k0 ⟫ 
+               nn06 = NN.nn-unique (nn i)
+     ... | suc k  | record {eq = eq} = record { k = k ; j = suc (NN.j (nn i)) ; sum = NN.sum (nn i) ; stage = NN.stage (nn i) ; nn = nn10
+         ; ni = cong suc (NN.ni (nn i)) ; k1 = nn11 ; k0 = nn12 ;  nn-unique = nn13 } where
+            nn10 : suc (NN.j (nn i)) + k ≡ NN.sum (nn i)
+            nn10 = begin
+                suc (NN.j (nn i)) + k ≡⟨ cong (λ x → x + k) (+-comm 1 _)  ⟩
+                (NN.j (nn i) + 1) + k ≡⟨  +-assoc (NN.j (nn i)) 1 k ⟩
+                NN.j (nn i) + suc k  ≡⟨ cong (λ k → NN.j (nn i) + k) (sym eq) ⟩
+                NN.j (nn i) + NN.k (nn i) ≡⟨ NN.nn (nn i) ⟩
+                NN.sum (nn i)  ∎   where open ≡-Reasoning 
+            nn11 :  nxn→n (suc (NN.j (nn i))) k ≡ suc i --  nxn→n ( NN.j (nn i)) (NN.k (nn i) ≡ i
+            nn11 = begin
+                nxn→n (suc (NN.j (nn i))) k   ≡⟨ sym (nid2 (NN.j (nn i)) k) ⟩
+                suc (nxn→n (NN.j (nn i)) (suc k)) ≡⟨ cong (λ k →   suc (nxn→n (NN.j (nn i)) k)) (sym eq) ⟩
+                suc (nxn→n ( NN.j (nn i)) (NN.k (nn i)))  ≡⟨ cong suc (NN.k1 (nn i)) ⟩
+                suc i  ∎   where open ≡-Reasoning 
+            nn18 :  zero < NN.k (nn i)
+            nn18 = subst (λ k → 0 < k ) ( begin
+                    suc k ≡⟨ sym eq ⟩
+                    NN.k (nn i)  ∎  ) (s≤s z≤n )  where open ≡-Reasoning  
+            nn12 :   n→nxn (suc i) ≡ ⟪ suc (NN.j (nn i)) , k ⟫  --  n→nxn i ≡ ⟪ NN.j (nn i) ,  NN.k (nn i)  ⟫
+            nn12 with  n→nxn i | inspect  n→nxn i
+            ... | ⟪ x , zero ⟫ | record { eq = eq1 } = ⊥-elim ( nat-≡< (sym (cong proj2 eq1))
+                (subst (λ k → 0 < k ) ( begin
+                    suc k ≡⟨ sym eq ⟩
+                    NN.k (nn i) ≡⟨ cong proj2 (sym (NN.k0 (nn i)) ) ⟩
+                    proj2 (n→nxn i) ∎  ) (s≤s z≤n )) ) where open ≡-Reasoning  --  eq1 n→nxn i ≡ ⟪ x , zero ⟫
+            ... | ⟪ x , suc y ⟫ | record { eq = eq1 } = begin -- n→nxn i ≡ ⟪ x , suc y ⟫
+                ⟪ suc x , y ⟫ ≡⟨ refl ⟩
+                ⟪ suc x , pred (suc y) ⟫ ≡⟨ cong (λ k → ⟪ suc (proj1 k) , pred (proj2 k) ⟫) ( begin
+                   ⟪ x , suc y ⟫  ≡⟨ sym eq1 ⟩
+                   n→nxn i ≡⟨ NN.k0 (nn i) ⟩
+                   ⟪ NN.j (nn i) , NN.k (nn i) ⟫ ∎ )  ⟩
+                ⟪ suc (NN.j (nn i)) , pred (NN.k (nn i)) ⟫ ≡⟨ cong (λ k →  ⟪ suc (NN.j (nn i)) , pred k ⟫) eq ⟩
+                ⟪ suc (NN.j (nn i)) , k ⟫ ∎   where open ≡-Reasoning 
+            nn13 :  {j0 k0 : ℕ} → nxn→n j0 k0 ≡ suc i → ⟪ suc (NN.j (nn i)) , k ⟫ ≡ ⟪ j0 , k0 ⟫
+            nn13 {zero} {suc k0} eq1 = ⊥-elim ( nat-≡< (sym (cong proj2 nn17)) nn18 ) where  -- (nxn→n zero (suc k0)) ≡ suc i
+                nn16 : nxn→n k0 zero ≡ i
+                nn16 =  cong pred ( subst (λ k → k ≡ suc i) (sym ( nid00 k0 )) eq1 )
+                nn17 : ⟪ NN.j (nn i) , NN.k (nn i) ⟫ ≡ ⟪ k0 , zero ⟫
+                nn17 = NN.nn-unique (nn i) nn16
+            nn13 {suc j0} {k0} eq1 = begin
+               ⟪ suc (NN.j (nn i)) , pred (suc k) ⟫ ≡⟨ cong (λ k →  ⟪ suc (NN.j (nn i)) , pred k ⟫ ) (sym eq) ⟩
+               ⟪ suc (NN.j (nn i)) , pred (NN.k (nn i)) ⟫ ≡⟨ cong (λ k → ⟪ suc (proj1 k) , pred (proj2 k) ⟫) ( begin 
+                 ⟪ NN.j (nn i) , NN.k (nn i) ⟫  ≡⟨ nn15 ⟩
+                 ⟪ j0 , suc k0 ⟫ ∎ ) ⟩
+               ⟪ suc j0 , k0 ⟫ ∎  where -- nxn→n (suc j0) k0 ≡ suc i
+                open ≡-Reasoning
+                nn14 : nxn→n j0 (suc k0) ≡ i
+                nn14 = cong pred ( subst (λ k → k ≡ suc i) (sym ( nid2 j0 k0 )) eq1 )
+                nn15 : ⟪ NN.j (nn i) , NN.k (nn i) ⟫ ≡ ⟪ j0 , suc k0 ⟫
+                nn15 = NN.nn-unique (nn i) nn14
+
+     n-id :  (i : ℕ) → nxn→n (proj1 (n→nxn i)) (proj2 (n→nxn i)) ≡ i
+     n-id i = subst (λ k →  nxn→n (proj1 k) (proj2 k)  ≡ i ) (sym (NN.k0 (nn i))) (NN.k1 (nn i))
+
+     nn-id : (j k : ℕ) → n→nxn (nxn→n j k) ≡ ⟪ j , k ⟫
+     nn-id j k = begin
+          n→nxn (nxn→n j k)  ≡⟨ NN.k0 (nn (nxn→n j k))   ⟩
+          ⟪ NN.j (nn (nxn→n j k)) , NN.k (nn (nxn→n j k)) ⟫ ≡⟨ NN.nn-unique (nn (nxn→n j k)) refl ⟩
+          ⟪ j , k ⟫ ∎  where open ≡-Reasoning
+
+
 b1 : (b : Bijection  ( ℕ → Bool ) ℕ) → ℕ 
 b1 b = fun→ b (diag b)