What can be inferred from the following premises in a single inference step (ignoring inferences that add new predicates or constants)? ~S(b_4) -> p_1. forall x_1: U_2(x_1) -> S(x_1). forall x_1: S(x_1) -> U_2(x_1). ~U_2(b_4).
forall x_1: U_2(x_1) <-> S(x_1). forall x_1: S(x_1) <-> U_2(x_1).