proposition: Lemma DoubleNoDup_cons_tl: forall x l, DoubleNoDup (x :: l) -> DoubleNoDup l.
proof: Proof. intros. destruct x as [x y]. unfold DoubleNoDup in *. simpl in H. destruct (split l) as [l1 l2]. simpl in H. apply NoDup_cons_1, NoDup_remove_1 in H. assumption. 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