namespace http://mathhub.info/MitM/core/calculus ❚
import base http://mathhub.info/MitM/Foundation ❚
import arith http://mathhub.info/MitM/core/arithmetics ❚
theory FinSequences : base:?Logic =
include ☞arith:?NaturalArithmetics ❙
below : ℕ ⟶ type ❘ = [n] ⟨ x : ℕ | ⊦ x < n ⟩ ❙
toBelow : {n : ℕ} below (Succ n) ❘# toB 1❙
succBelow : {n : ℕ} below n ⟶ below (Succ n) ❘# succB 2❙
belowIsSubtypeOfNat : {n : ℕ} (below n) <* ℕ ❙
belowToNat : {n : ℕ} below (Succ n) ⟶ ℕ ❘# btn 1 2❙
belowToNatBaseCase : {m : ℕ} ⊦ belowToNat m (toBelow m) ≐ m❙
belowToNatRecCase : {m : ℕ, b : below (Succ m)} ⊦ belowToNat (Succ m) (succBelow (Succ m) b) ≐ belowToNat m b ❙
belowToNatExample : ⊦ btn 3 (toB 3) ≐ 3❙
belowToNatExample2 : ⊦ btn 4 (succB (toB 3)) ≐ 3 ❙
belwoToNatExample2_2 : ⊦ belowToNat (Succ 3) (succBelow (Succ 3) (toBelow 3)) ≐ 3❙
// belowToNat2 : {n : ℕ} below (Succ n) ⟶ ℕ ❘= [n, b] n ❘# btn2 %I1 ❙
// belowToNat3 : {n : ℕ, m : ℕ} below n ⟶ ⊦ m < n ⟶ ℕ ❘= [n , m , b, p ] m ❘# btn3 %I1 ❙
// belowToNat4 : {n : ℕ} below n ⟶ ⟨ ℕ | [x] ⊦ x < n⟩ ❘# btn4 %I1❙
finSeq : ℕ ⟶ type ⟶ type ❘= [n , A] below n ⟶ A ❙
nonEmptyFinSeq_prop : {n : ℕ, A : type} finSeq n A ⟶ bool ❘= [n, A , f] 0 < n ❘# nefs %I1 %I2 ❙
disjointFinSeq_prop : {n : ℕ, A : type} finSeq n A ⟶ bool❙
disjointFinSeq_prop_trivial : {A : type,f : finSeq 0 A} ⊦ disjointFinSeq_prop 0 A f ≐ true❙
disjointFinSeq_prop_step // : {A : type , n : ℕ , f :
finSeq (succ n) A} ⊦ disjointFinSeq_prop (succ n) A f ≐ ∀ [m1 : below (succ n)] ∀ [m2 : below (succ n)] ⊦ m1 ≠ m2 ⟶ ⊦ true ❙
belowShift : {n : ℕ , m : ℕ} below n ⟶ below (n + m)❙
// belowShift_base : {n, b} ⊦ belowShift n 0 b ≐ b❙
// finSeqSum : {n : ℕ , b : below n} ❙
❚