Some definitions of interest.
sfa_doc_greater_list_bound	Def y greater-bounds x == i:||x||. x[i]<y
	Thm* x: List, y:. y greater-bounds x  Prop
int_seg	Def {i..j} == {k:| i  k < j }
	Thm* m,n:. {m..n}  Type
length	Def ||as|| == Case of as; nil  0 ; a.as'  ||as'||+1  (recursive)
	Thm* A:Type, l:A List. ||l||
	Thm* ||nil||
nat	Def  == {i:| 0i }
	Thm*   Type

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