proposition: Lemma reachable_by_through_app': forall g P l1 l2, Same_set (reachable_by_through_set g (l1 ++ l2) P) (Union _ (reachable_by_through_set g l1 P) (reachable_by_through_set g l2 P)).
proof: Proof. intros. rewrite Same_set_spec; intro n; rewrite Union_spec. apply reachable_by_through_app. 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