Some definitions of interest.
assoced	Def a ~ b == a | b & b | a
	Thm* a,b:. (a ~ b)  Prop
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