What can be inferred from the following premises in a single inference step (ignoring inferences that add new predicates or constants)? U(g_2) <-> t. ~t. forall z_3: R(z_3) <-> U(z_3).
U(g_2) -> t. t -> U(g_2). ~U(g_2). forall z_3: R(z_3) -> U(z_3). forall z_3: U(z_3) -> R(z_3).