Nuprl - Proof: swap adjacent instance 2 2 1 2 1 1

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At: swap adjacent instance 2 2 1 2 1 1

1. A : Type
2. P : A

Prop
3. X : A List
4. Y : A List
5. a : A
6. b : A
7. P(a,b)
8. i :

9. i<||X @ [b; a / Y]||
10.

i<||X||
11. i = ||X||

(X @ [b; a / Y])[||X||] = (X @ [a; b / Y])[((||X||, ||X||+1)(||X||))]

By:	Subst' ((\|\|X\|\|, \|\|X\|\|+1)(\|\|X\|\|) = \|\|X\|\|+1) 0 THEN Try (Unfold `flip` 0 THEN Reduce 0 THEN Repeat SplitOnConclITE)

Generated subgoal:

1 (X @ [b; a / Y])[||X||] = (X @ [a; b / Y])[(||X||+1)]
2 steps

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