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 z_1: Q(z_1) -> R_4(z_1). forall z_1: P_3(z_1) -> R_4(z_1). exists z_1: R_4(z_1) -> Q(z_1). forall z_1: Q(z_1).
forall z_1: R_4(z_1) can be inferred via the universal modus ponens rule. exists z_1: P_3(z_1) -> Q(z_1) can be inferred via the existential transitivity rule. exists z_1: R_4(z_1) <-> Q(z_1) can be inferred via the existential biconditional introduction rule. exists z_1: Q(z_1) <-> R_4(z_1) can be inferred via the existential biconditional introduction rule.