proposition: Lemma get_edges_inv: forall g v e, In e (get_edges g v) <-> exists idx, e = (v, idx) /\ In idx (map snd (get_edges g v)).
proof: Proof. intros. destruct e as [gen idx]. split; intros. - pose proof H. apply get_edges_fst in H0. simpl in H0. subst gen. exists idx. rewrite get_edges_In in H. split; auto. - destruct H as [? [? ?]]. inversion H. subst. rewrite get_edges_In. assumption. Qed.
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