proposition: Lemma Dup_unfold {A} {EA : EqDec A eq}: forall (a : A) (L : list A), Dup (a :: L) -> In a L \/ Dup L.
proof: Proof. intros; destruct (in_dec equiv_dec a L); [left; trivial | right; intro; apply H; constructor; auto]. Qed.
imports: Coq.Lists.List Coq.micromega.Lia Coq.Sorting.Permutation Coq.ZArith.ZArith_base Coq.ZArith.Zcomplements Coq.Logic.FunctionalExtensionality CertiGraph.lib.Coqlib CertiGraph.lib.EquivDec_ext VST.zlist.sublist VST.zlist.list_solver