proposition: Lemma oiso2_remove_vertex_ (F G : pre_graph) (z z' : VT) (j : F ⩭2 G) : z \in vset F -> z \notin pIO F -> z' = j z -> F \ z ⩭2 G \ z'.
proof: Proof. move => ? ? ->. exact: oiso2_remove_vertex. Qed.
imports: Coq(Relation_Definitions Morphisms RelationClasses) mathcomp(all_ssreflect) GraphTheory(edone finite_quotient preliminaries bij equiv) GraphTheory(setoid_bigop structures pttdom mgraph mgraph2) GraphTheory(rewriting open_confluence finmap_plus)