proposition: Lemma local_dag_step: forall (g: Graph) x y, localDag g x -> vvalid g x -> step g x y -> localDag g y.
proof: Proof. intros. unfold localDag in *. intros z ?. apply (H z). apply step_reachable with y; auto. Qed.
imports: Coq.Logic.ProofIrrelevance Coq.Sets.Ensembles Coq.Sets.Finite_sets Coq.Lists.List Coq.Classes.Morphisms CertiGraph.lib.Coqlib CertiGraph.lib.List_ext CertiGraph.lib.EquivDec_ext VST.msl.Coqlib2 CertiGraph.graph.graph_model CertiGraph.graph.path_lemmas CertiGraph.graph.reachable_computable CertiGraph.graph.reachable_ind CertiGraph.graph.subgraph2