fact: Definition matching (G : sgraph) (M : {set {set G}}) := {subset M <= E(G) } /\ {in M&, forall (e1 e2 : {set G}) (x:G), x \in e1 -> x \in e2 -> e1 = e2}.
imports: mathcomp(all_ssreflect) GraphTheory(edone preliminaries digraph mgraph sgraph set_tac)