is mentioned by

Def Graph(a:A -- > f(a;b) | b:B) == < vertices = A, edges = AB, incidence = < a,b > . < a,f(a;b) > >	[fun-graph]
Def Graph(x,y:T. R(x;y)) == < vertices = T, edges = {p:(TT)| R(1of(p);2of(p)) }, incidence = Id >	[rel-graph]

Try larger context: Graphs