proposition: Lemma flip_edgeK' (G : pre_graph) (e : ET) (E : {fset ET}) : e \in E -> (flip_edge G e) - E ≡G G - E.
proof: Proof. move => He. split; rewrite //= ?edges_at_flip_edge //. - move => b e' /fsetDP [A B]. rewrite updateE //. by apply: contraNneq B => ->. - move => e' /fsetDP [A B]. rewrite updateE //. by apply: contraNneq B => ->. 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)