proposition: Lemma reachable_by_through_singleton': forall g P n, Same_set (reachable_by_through_set g (n :: nil) P) (reachable_by g n P).
proof: Proof. intros. rewrite Same_set_spec; intro n'. apply reachable_by_through_singleton. 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