proposition: Lemma var_cons_notSubst G x : (None::G) |-> (S x)/- -> G |-> x/- .
proof: Proof. destruct 1. constructor; trivial. constructor 2; trivial. Qed.
imports: CoLoR(RelExtras ListPermutation TermsConv ListUtil ListExtras LogicUtil) Coq(Arith Lia)