Some definitions of interest.
assoced	Def a ~ b == a | b & b | a
	Thm* a,b:. (a ~ b)  Prop
divides	Def b | a == c:. a = bc
	Thm* a,b:. (a | b)  Prop
int_nzero	Def  == {i:| i  0 }
	Thm*   Type

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