proposition: Lemma oarc_vsetR (isG : is_graph G) e x y u : oarc G e x u y -> y \in vset G.
proof: Proof. case => E [b] [_ <- _]. exact: endptP. Qed.
imports: HB(structures) Coq(Relation_Definitions Morphisms RelationClasses) mathcomp(all_ssreflect) GraphTheory(edone finite_quotient preliminaries bij equiv) GraphTheory(setoid_bigop structures pttdom rewriting) GraphTheory(finmap_plus)