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: U_1(y). exists y: P(y) <-> S_1(y). forall y: S_1(y). forall y: U_1(y) -> Q_4(y).
forall y: Q_4(y) can be inferred via the universal modus ponens rule. forall y: U_1(y) and S_1(y) can be inferred via the universal conjunction rule. forall y: S_1(y) and U_1(y) can be inferred via the universal conjunction rule. exists y: P(y) -> S_1(y) can be inferred via the existential biconditional elimination rule. exists y: S_1(y) -> P(y) can be inferred via the existential biconditional elimination rule.