Some definitions of interest.
factorial_tail_via_iter	Def  k!m ==  i:{k-m..k}. i+1
	Thm*  m,k:. k!m
lele	Def  i  j  k == ij & jk
nat	Def   == {i:| 0i }
	Thm*    Type

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