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_2: U_1(z_2) -> W(z_2). forall z_2: U(z_2). exists z_2: U_1(z_2) <-> U(z_2).
exists z_2: U_1(z_2) -> U(z_2) can be inferred via the existential biconditional elimination rule. exists z_2: U(z_2) -> U_1(z_2) can be inferred via the existential biconditional elimination rule.