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_24: P_21(x_24) <-> Q_21(x_24). forall x_24: P_21(x_24) or T(x_24). exists x_24: ~Q_21(x_24). forall x_24: T(x_24) -> P_24(x_24). forall x_24: P_24(x_24) <-> Q_24(x_24).
forall x_24: P_21(x_24) -> Q_21(x_24) can be inferred via the universal biconditional elimination rule. forall x_24: P_24(x_24) -> Q_24(x_24) can be inferred via the universal biconditional elimination rule. forall x_24: Q_21(x_24) -> P_21(x_24) can be inferred via the universal biconditional elimination rule. forall x_24: Q_24(x_24) -> P_24(x_24) can be inferred via the universal biconditional elimination rule. exists x_24: ~P_21(x_24) can be inferred via the existential biconditional elimination rule.