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_15: P_15(x_15) -> ~Q_15(x_15). forall x_15: P_11(x_15) or ~R_4(x_15). forall x_15: P_11(x_15) -> R_4(x_15). exists x_15: P_15(x_15) <-> P_11(x_15). forall x_15: Q_15(x_15).
forall x_15: ~P_15(x_15) can be inferred via the universal modus tollens rule. forall x_15: R_4(x_15) -> P_11(x_15) can be inferred via the universal rewriting rule. exists x_15: P_15(x_15) -> P_11(x_15) can be inferred via the existential biconditional elimination rule. exists x_15: P_11(x_15) -> P_15(x_15) can be inferred via the existential biconditional elimination rule.