IF YOU CAN SEE THIS go to /sfa/Nuprl/Shared/Xindentation_hack_doc.html
At:
dec iff ex bvfun1 1. T : Type
2. E : TTProp
3. x,y:T. Dec(E(x,y))
f:(TT). x,y:T. f(x,y) E(x,y)
By:
(RenameVar `g' 3) THEN (Unfold `decidable` 3)
THEN
Witness x,y. InjCase(g(x,y); a. true; b. false)
THEN
(Reduce 0)