proposition: Lemma graph_has_v_dec: forall (g: LGraph) (v: VType), {graph_has_v g v} + {~ graph_has_v g v}.
proof: Proof. intros. destruct v as [vgen vidx]. destruct (graph_has_gen_dec g vgen). - destruct (gen_has_index_dec g vgen vidx). 1: left; red; simpl; split; auto. right; intro; apply n; destruct H; auto. - right; intro; apply n; destruct H; auto. Defined.
imports: Coq.ZArith.ZArith Coq.Program.Basics compcert.lib.Integers compcert.common.Values VST.veric.base VST.veric.Clight_lemmas VST.veric.val_lemmas VST.veric.shares VST.msl.seplog VST.msl.shares VST.zlist.sublist VST.floyd.coqlib3 VST.floyd.functional_base VST.floyd.data_at_rec_lemmas CertiGraph.lib.Coqlib CertiGraph.lib.EquivDec_ext CertiGraph.lib.List_ext CertiGraph.graph.graph_model CertiGraph.graph.graph_gen CertiGraph.graph.path_lemmas CertiGraph.graph.subgraph2 CertiGraph.graph.graph_relation CertiGraph.graph.graph_isomorphism CertiGraph.graph.reachable_ind CertiGraph.CertiGC.GCGraph