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_8: P(x_8) or P_8(x_8). forall x_8: P(x_8) -> Q_1(x_8). forall x_8: Q_1(x_8) -> Q_8(x_8). exists x_8: P_8(x_8) <-> Q_8(x_8).
forall x_8: P(x_8) -> Q_8(x_8) can be inferred via the universal transitivity rule. exists x_8: P_8(x_8) -> Q_8(x_8) can be inferred via the existential biconditional elimination rule. exists x_8: Q_8(x_8) -> P_8(x_8) can be inferred via the existential biconditional elimination rule.