proposition: Lemma valid_upath_exists_list_edges': forall g p, (exists l, fits_upath g l p) -> valid_upath g p.
proof: Proof. induction p; intros. simpl. auto. destruct H as [l ?]. destruct p. simpl. destruct l; simpl in H; [auto | contradiction]. destruct l. simpl in H; contradiction. destruct H. split. exists e; apply H. apply IHp. exists l. apply H0. Qed.
imports: Coq.Logic.Classical CertiGraph.lib.List_ext CertiGraph.lib.EquivDec_ext CertiGraph.graph.graph_model CertiGraph.graph.graph_relation CertiGraph.graph.path_lemmas CertiGraph.graph.graph_gen CertiGraph.graph.FiniteGraph