What can be inferred from the following premises in a single inference step (ignoring inferences that add new predicates or constants)? forall x: ~P(x). exists x: P(x) -> U_1(x). forall x: U_1(x) -> P(x). forall x: U_1(x) -> T_4(x). forall x: T_4(x) -> U_1(x).
forall x: ~U_1(x). forall x: T_4(x) -> P(x). exists x: P(x) -> T_4(x). forall x: U_1(x) <-> T_4(x). forall x: T_4(x) <-> U_1(x). exists x: P(x) <-> U_1(x). exists x: U_1(x) <-> P(x).