Some definitions of interest.
compose_iter	Def  f{i}(x) == if i=0 x else f(f{i-1}(x)) fi  (recursive)
	Thm*  f:(AA), i:. f{i}  AA
int_iseg	Def  {i...j} == {k:| ik & kj }
	Thm*  i,j:. {i...j}  Type
nat	Def   == {i:| 0i }
	Thm*    Type

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