fact: Definition t_x_W : poly_type := many_poly_abs n_W' (poly_arr t_x_W' t_x_W').
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