IF YOU CAN SEE THIS go to /sfa/Nuprl/Shared/Xindentation_hack_doc.html
At:
proper sublist length11 1. T : Type
2. L1 : T List
3. L2 : T List
4. f : ||L1||||L2||
5. increasing(f;||L1||)
6. j:||L1||. L1[j] = L2[(f(j))]
7. ||L1|| = ||L2||
8. i :
9. i<||L1||
10. L1[i] = L2[(f(i))]
L1[i] = L2[i]