proposition: Lemma eqvb_neq u v (b : bool) : u ≡[~~b] v <-> u ≡[b] v°.
proof: Proof. by split; apply: eqvb_transL; rewrite ?(addbN,addNb) addbb /= ?eqvE' ?cnvI. Qed.
imports: HB(structures) Coq(Setoid Morphisms) mathcomp(all_ssreflect) GraphTheory(edone preliminaries setoid_bigop structures)