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_12: P_12(x_12) -> Q_12(x_12). forall x_12: Q_12(x_12) -> P_12(x_12). t_3. ~P_12(b).
t_3 and ~P_12(b) can be inferred via the conjunction rule. ~P_12(b) and t_3 can be inferred via the conjunction rule. forall x_12: P_12(x_12) <-> Q_12(x_12) can be inferred via the universal biconditional introduction rule. forall x_12: Q_12(x_12) <-> P_12(x_12) can be inferred via the universal biconditional introduction rule.