Some definitions of interest.
factorial_via_iter	Def  k! == k!k
	Thm*  k:. k!
nat	Def   == {i:| 0i }
	Thm*    Type
nat_plus	Def   == {i:| 0<i }
	Thm*    Type

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