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_11: Q(x_11) <-> P_11(x_11). forall x_11: P_11(x_11) -> ~Q_11(x_11). forall x_11: Q_11(x_11). Q(a_5) <-> u_2.
Q(a_5) -> u_2 can be inferred via the biconditional elimination rule. u_2 -> Q(a_5) can be inferred via the biconditional elimination rule. forall x_11: ~P_11(x_11) can be inferred via the universal modus tollens rule. forall x_11: Q(x_11) -> P_11(x_11) can be inferred via the universal biconditional elimination rule. forall x_11: P_11(x_11) -> Q(x_11) can be inferred via the universal biconditional elimination rule.