What can be inferred from the following premises in a single inference step (ignoring inferences that add new predicates or constants)? forall y: Q_1(y) <-> R_1(y). forall y: Q_1(y) <-> R_1(y).
forall y: Q_1(y) -> R_1(y). forall y: Q_1(y) -> R_1(y). forall y: R_1(y) -> Q_1(y). forall y: R_1(y) -> Q_1(y).