proposition: Lemma reachable_head_valid: forall (g : Gph) n1 n2, reachable g n1 n2 -> vvalid g n1.
proof: Proof. intros; eapply reachable_by_head_valid; eauto. Qed.
imports: Coq.Logic.ProofIrrelevance Coq.micromega.Lia CertiGraph.lib.Coqlib CertiGraph.lib.EnumEnsembles CertiGraph.lib.List_ext CertiGraph.lib.EquivDec_ext CertiGraph.graph.graph_model Coq.Lists.List Coq.Lists.ListDec