proposition: Lemma gc_graph_iso_trans: forall g2 roots2 g1 roots1 g3 roots3, gc_graph_iso g1 roots1 g2 roots2 -> gc_graph_iso g2 roots2 g3 roots3 -> gc_graph_iso g1 roots1 g3 roots3.
proof: Proof. intros. unfold gc_graph_iso in *. destruct H as [v12 [v21 [e12 [e21 [? ?]]]]]. destruct H0 as [v23 [v32 [e23 [e32 [? ?]]]]]. exists (compose v23 v12), (compose v21 v32), (compose e23 e12), (compose e21 e32). split; [|eapply lp_graph_iso_exp_trans; eauto]. rewrite H0. rewrite H. rewrite map_map. clear. induction roots1; simpl; auto. rewrite IHroots1. f_equal. now destruct a. 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