fact: Definition pack_add_vertex (G : pre_graph) (graph_G : is_graph G) x a : x \notin vset G -> pack (G ∔ [x, a]) ≃2 (pack G) ∔ a.
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)