Who Cites singleton?
singleton	Def {a:T} == {x:T| x = a  T }
	Thm* T:Type, a:T. {a:T}  Type

Syntax:

{a:T}

has structure:

singleton(a; T)

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