proposition: Lemma osteps_graph (F G : pre_graph) (isG : is_graph F) : osteps F G -> is_graph G.
proof: Proof. move => S. elim: S isG => {F G}. - move => F G FG H. by eauto using eqvG_graph. - move => F G FG H. destruct FG. eauto using add_edge_graph''. - move => F G FG isF. apply: ostep_graph FG. - move => F G H. tauto. 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)