At: quotient of nsubn21211211211223 1. n: {1+1...} 2. E:((n-1)(n-1)Prop).
(EquivRel x,y:(n-1). x E y) & (x,y:(n-1). Dec(x E y))
(m:(n-1+1). m ~ (i,j:(n-1)//(i E j))) 3. E: nnProp 4. EquivRel x,y:n. x E y 5. x,y:n. Dec(x E y) 6. EquivRel x,y:(n-1). x E y 7. m: (n-1+1) 8. f: m(i,j:(n-1)//(i E j)) 9. g: (i,j:(n-1)//(i E j))m 10. InvFuns(m; i,j:(n-1)//(i E j); f; g) 11. x:m. f(x) i,j:n//(i E j) 12. a:n. a E a 13. a,b:n. (a E b) (b E a) 14. a,b,c:n. (a E b) (b E c) (a E c) 15. x,y:i,j:n//(i E j). Dec(x = y) 16. Eb: (i,j:n//(i E j))(i,j:n//(i E j)) 17. x,y:i,j:n//(i E j). (x Eb y) x = y 18. (k:(n-1). k E (n-1)) 19. n-1 i,j:n//(i E j) 20. f1: (m+1)(i,j:n//(i E j)) 21. f1 = (x.if x=m n-1 else f(x) fi)
m:(n+1), f:(m(i,j:n//(i E j))), g:((i,j:n//(i E j))m). InvFuns(m; i,j:n//(i E j); f; g) By: Let (g1 = (x.if x Eb (n-1) m else g(x) fi)) Generated subgoals:
22. g1: (i,j:n//(i E j))(m+1) 23. g1 = (x.if x Eb (n-1) m else g(x) fi) m:(n+1), f:(m(i,j:n//(i E j))), g:((i,j:n//(i E j))m). InvFuns(m; i,j:n//(i E j); f; g)