Some definitions of interest.
eq_int	Def i=j == if i=j true ; false fi
	Thm* i,j:. (i=j)
int_seg	Def {i..j} == {k:| i  k < j }
	Thm* m,n:. {m..n}  Type
nat	Def  == {i:| 0i }
	Thm*   Type
not	Def A == A  False
	Thm* A:Prop. (A)  Prop

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