proposition: Lemma vgamma_not_reachable': forall (g: UFGraph) x r pa y, vvalid g x -> vgamma g x = (r, pa) -> pa <> x -> reachable g pa y -> ~ reachable g y x.
proof: Proof. intros. apply (dst_not_reachable _ (liGraph g) _ pa); auto. apply (vgamma_not_dst g x r); auto. Qed.
imports: Coq.Sets.Ensembles Coq.Lists.List CertiGraph.lib.EquivDec_ext CertiGraph.lib.Coqlib CertiGraph.lib.Ensembles_ext CertiGraph.graph.graph_model CertiGraph.graph.path_lemmas CertiGraph.graph.reachable_computable CertiGraph.graph.graph_gen CertiGraph.graph.FiniteGraph CertiGraph.graph.MathGraph CertiGraph.graph.LstGraph CertiGraph.graph.UnionFind