Some definitions of interest.
nat	Def  == {i:| 0i }
	Thm*   Type
squash	Def T == {:True| T }
	Thm* A:Prop. A  Prop
wellfounded	Def WellFnd{i}(A;x,y.R(x;y)) Def == P:(AProp). (j:A. (k:A. R(k;j)  P(k))  P(j))  {n:A. P(n)}
	Thm* A:Type{i}, r:(AAProp{i}). WellFnd{i}(A;x,y.r(x,y))  Prop{i'}

About: IF YOU CAN SEE THIS go to /sfa/Nuprl/Shared/Xindentation_hack_doc.html