proposition: Lemma reachable_decidable: forall x, {vvalid G x} + {~ vvalid G x} -> EnumCovered V (reachable G x) -> forall y, {reachable G x y} + {~ reachable G x y}.
proof: Proof. intros. destruct H as [H | H]. + apply reachable_decidable_prime; auto. + right. intro. apply reachable_head_valid in H0. tauto. Qed.
imports: Coq.Sets.Finite_sets Coq.Arith.Arith Coq.Logic.ProofIrrelevance Coq.Logic.FunctionalExtensionality Coq.Sorting.Permutation Coq.micromega.Lia CertiGraph.lib.Coqlib CertiGraph.lib.List_ext CertiGraph.lib.EquivDec_ext CertiGraph.lib.EnumEnsembles Coq.Lists.List VST.msl.Coqlib2 CertiGraph.graph.graph_model CertiGraph.graph.path_lemmas CertiGraph.graph.reachable_ind CertiGraph.graph.subgraph2 CertiGraph.graph.graph_gen CertiGraph.graph.MathGraph CertiGraph.graph.FiniteGraph