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 x: Q(x) -> Q_4(x). forall x: U(x) <-> S_2(x). exists x: Q_4(x) -> S_2(x).
exists x: Q(x) -> S_2(x) can be inferred via the existential transitivity rule. forall x: U(x) -> S_2(x) can be inferred via the universal biconditional elimination rule. forall x: S_2(x) -> U(x) can be inferred via the universal biconditional elimination rule.