proposition: Lemma vertex_rep_isptr: forall sh g v, vertex_rep sh g v |-- !! (isptr (gen_start g (vgeneration v))).
proof: Proof. intros. destruct v as [gen num]. unfold vertex_rep, vertex_at. rewrite vertex_head_address_eq. simpl. rewrite data_at_isptr. Intros. apply prop_right. unfold offset_val in H. destruct (gen_start g gen); try contradiction. exact I. Qed.
imports: VST.veric.compcert_rmaps VST.msl.shares VST.msl.wand_frame VST.concurrency.conclib CertiGraph.lib.List_ext CertiGraph.msl_ext.log_normalize CertiGraph.msl_ext.ramification_lemmas CertiGraph.graph.graph_model CertiGraph.CertiGC.GCGraph CertiGraph.CertiGC.env_graph_gc CertiGraph.msl_ext.iter_sepcon Coq.Lists.List