proposition: Lemma upd_Znth_pos_cons: forall {A: Type} (i: Z) (l: list A) v x, (0 < i <= Zlength l)%Z -> upd_Znth i (v :: l) x = v :: upd_Znth (i - 1) l x.
proof: Proof. intros. unfold_upd_Znth_old. rewrite (sublist_split 0 1 i); [| |rewrite Zlength_cons]; [| lia..]. unfold sublist at 1. simpl. rewrite !sublist_pos_cons by lia. do 4 f_equal. 1: lia. rewrite Zlength_cons; lia. Qed.
imports: Coq.ZArith.ZArith Coq.Program.Basics Coq.micromega.Lia 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 VST.zlist.list_solver CertiGraph.lib.EquivDec_ext CertiGraph.lib.List_ext CertiGraph.graph.graph_model CertiGraph.graph.graph_gen