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: exists x_12: P_12(x_12). forall x_12: Q(x_12). forall x_12: P_12(x_12) <-> U(x_12).
exists x_12: P_12(x_12) and Q(x_12) can be inferred via the existential conjunction rule. exists x_12: Q(x_12) and P_12(x_12) can be inferred via the existential conjunction rule. forall x_12: P_12(x_12) -> U(x_12) can be inferred via the universal biconditional elimination rule. forall x_12: U(x_12) -> P_12(x_12) can be inferred via the universal biconditional elimination rule.