What can be inferred from the following premises in a single inference step (ignoring inferences that add new predicates or constants)? Name the inference rule being used: forall y: P_4(y) <-> S(y). forall y: P_4(y). forall y: S_1(y).
forall y: P_4(y) and S_1(y) can be inferred via the universal conjunction rule. forall y: S_1(y) and P_4(y) can be inferred via the universal conjunction rule. forall y: P_4(y) -> S(y) can be inferred via the universal biconditional elimination rule. forall y: S(y) -> P_4(y) can be inferred via the universal biconditional elimination rule.