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: exists z: U_3(z) -> S(z). forall z: S(z) -> U_3(z).
exists z: U_3(z) <-> S(z) can be inferred via the existential biconditional introduction rule. exists z: S(z) <-> U_3(z) can be inferred via the existential biconditional introduction rule.