IF YOU CAN SEE THIS go to /sfa/Nuprl/Shared/Xindentation_hack_doc.html
At:
sum switch1 1. n : 2. f : n 3. i : (n-1)
sum(f((i, i+1)(x)) | x < n) = sum(f(x) | x < n)
By:
Inst Thm* k:, i,j:k. (i, j) kk [n;i;i+1]
THEN
Subst'
(sum(f((i, i+1)(x)) | x < n)
(=
(sum(f((i, i+1)(x)) | x < i)+sum(f((i, i+1)(x+i)) | x < n-i))
0