proposition: Lemma subst_poly_type_Ut' {ts t} : let σ := fold_right scons poly_var ts in subst_poly_type σ (Ut' (length ts) t) = Ut (subst_poly_type σ t).
proof: Proof. by rewrite /= ?fold_right_length_ts. Qed.
imports: PeanoNat List Lia Undecidability.SystemF.SysF Undecidability.SystemF.Autosubst.syntax Undecidability.SystemF.Util(Facts poly_type_facts term_facts typing_facts iipc2_facts sn_facts) Undecidability.DiophantineConstraints.H10C ssreflect ssrbool ssrfun