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: ~U_1(z). exists z: U_1(z) <-> W(z).
exists z: U_1(z) -> W(z) can be inferred via the existential biconditional elimination rule. exists z: W(z) -> U_1(z) can be inferred via the existential biconditional elimination rule. exists z: ~W(z) can be inferred via the existential biconditional elimination rule.