proposition: Lemma map_expr_size_subst_map_expr v v' m : map_expr_size (subst_map_expr m v v') = map_expr_size m.
proof: Proof. induction m; simpl; auto. Qed.
imports: Coq.NArith.NArith Coq.FSets.FMaps Coq.micromega.Lia Category.Lib Category.Lib.FMapExt