proposition: Fact many_argument_app_app {P As As'} : many_argument_app P (As ++ As') = many_argument_app (many_argument_app P As) As'.
proof: Proof. by rewrite /many_argument_app fold_left_app. Qed.
imports: List Lia Undecidability.SystemF.SysF Undecidability.SystemF.Autosubst.syntax Undecidability.SystemF.Autosubst.unscoped Undecidability.SystemF.Util(Facts poly_type_facts pure_term_facts) ssreflect ssrbool ssrfun