IF YOU CAN SEE THIS go to /sfa/Nuprl/Shared/Xindentation_hack_doc.html
At:
card sum family singleton elim1 1. A : Type
2. a : A 3. B : {x:A| x = a }Type
(i:{x:A| x = a }B(i)) ~ B(a)
By:
(ib.ib/i,b. b) (i:{x:A| x = aA }B(i))B(a) Asserted
THEN
Witness: ib.ib/i,b. b | b.<a,b>