proposition: Lemma progressive_repeat: forall n, repeat (Vundef, Vundef) n = progressive_list O n.
proof: Proof. induction n; unfold progressive_list; simpl; auto. unfold progressive_list in IHn. rewrite <- IHn. change ((Vundef, Vundef) :: repeat (Vundef, Vundef) n) with (((Vundef, Vundef) :: nil) ++ repeat (Vundef, Vundef) n). change ((Vundef, Vundef) :: nil) with (repeat (Vundef, Vundef) 1). rewrite <- !repeat_app. rewrite Nat.add_comm. auto. Qed.
imports: CertiGraph.lib.List_ext CertiGraph.unionfind.env_unionfind_arr CertiGraph.graph.graph_model CertiGraph.graph.path_lemmas CertiGraph.graph.subgraph2 CertiGraph.graph.graph_relation CertiGraph.graph.reachable_computable CertiGraph.graph.UnionFind CertiGraph.msl_application.ArrayGraph CertiGraph.floyd_ext.share CertiGraph.unionfind.spatial_array_graph Coq.Lists.List CertiGraph.unionfind.uf_arr_specs VST.floyd.library