At: nd ext valcom 1 1 2 1 1 1 1 1 1 1 1 5 1 1 1 1 2 2 1 1 1 1 1 1 1 1 1
1. Alph: Type
2. St: Type
3. NDA: NDA(Alph;St)
4. C: (St
Alph*)*
5. ||C|| > 0
6. 
i:
(||C||-1). ||2of(C[i])|| > 0
7. q: St
8. a: Alph
9. p: St
10. I(NDA) = 1of(hd(C))
11. i:(||C||-1).
NDA(1of(C[i]),hd(rev(2of(C[i]))),1of(C[(i+1)])) & 2of(C[(i+1)]) = rev(tl(rev(2of(C[i]))))
12. 1of(hd(rev(C))) = q
13. NDA(q,a,p)
14. i: 
15. 0
i
16. i < ||map(
c. < 1of(c),a.2of(c) > ;C)||+1-1
17. i = ||C||-1
18. i+1-||map(c. < 1of(c),a.2of(c) > ;C)|| = 0 
1
19. 2of(C[i]) = nil
20. rev(2of(C[i])) = (Case of nil; nil 
nil ; a.as' rev(as') @ [a])
21. rev(2of(C[i])) = rev(nil)
rev(2of(C[i])) = nil
By:
RW (NthC 2 (RecUnfoldTopC `reverse`)) 21
THEN
Reduce 21
Generated subgoals:None
About:
