proposition: Lemma envSubst_extends_trans : forall S1 S2 S3, S1 |=> S2 -> S2 |=> S3 -> S1 |=> S3.
proof: Proof. fo. Qed.
imports: CoLoR(RelExtras ListPermutation TermsPos ListUtil ListExtras LogicUtil) Coq(Compare_dec Setoid Morphisms Lia PeanoNat)