proposition: Lemma size_exp_open_exp_wrt_exp_rec : forall e1 e2 n1, size_exp e1 <= size_exp (open_exp_wrt_exp_rec n1 e2 e1).
proof: Proof. pose proof size_exp_open_exp_wrt_exp_rec_mutual as H; intuition eauto. Qed.
imports: Coq.Logic.FunctionalExtensionality Coq.Program.Equality Metalib.Metatheory Metalib.LibLNgen Stlc