IF YOU CAN SEE THIS go to /sfa/Nuprl/Shared/Xindentation_hack_doc.html
At:
nsub inj fill typing1121 1. a :
2. b :
3. j : b 4. f : (a-1){x:b| x = j }
5. Inj((a-1); {x:b| x = j }; f)
6. (i.if i=a-1 j else f(i) fi) ab 7. a1 : a 8. a2 : a 9. if a1=a-1 j else f(a1) fi = if a2=a-1 j else f(a2) fi
a1 = a2