Some definitions of interest.
rev_implies	Def P  Q == Q  P
	Thm* A,B:Prop. (A  B)  Prop
singleton	Def {a:T} == {x:T| x = a  T }
	Thm* T:Type, a:T. {a:T}  Type
stype	Def S == {T:Type| x:T. True }
	Thm* S  Type{2}

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