proposition: Lemma is_simple_t_1_W : is_simple t_1_W.
proof: Proof. by rewrite /t_1_W /= /SUt0' /SUt1' /SUs' ?is_simple_SU_term_to_poly_type. Qed.
imports: List Lia Undecidability.SystemF.SysF Undecidability.SystemF.Autosubst.syntax Undecidability.SystemF.Util(Facts poly_type_facts pure_term_facts term_facts typing_facts pure_typing_facts pure_typable_prenex) ssreflect ssrbool ssrfun