What can be inferred from the following premises in a single inference step (ignoring inferences that add new predicates or constants)? forall y: ~P_4(y). forall y: R(y) <-> P_4(y). forall y: R(y) -> Q_1(y). exists y: Q_1(y) -> R(y).
exists y: Q_1(y) <-> R(y). exists y: R(y) <-> Q_1(y). forall y: R(y) -> P_4(y). forall y: P_4(y) -> R(y). forall y: ~R(y).