proposition: Lemma reachable_by_through_nil: forall g P n, reachable_by_through_set g nil P n <-> False.
proof: Proof. intros; split; intro. + destruct H as [s [? ?]]. inversion H. + exfalso; auto. 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