What can be inferred from the following premises in a single inference step (ignoring inferences that add new predicates or constants)? forall x_11: U_2(x_11) <-> S_11(x_11). r. ~U_2(a_11).
r and ~U_2(a_11). ~U_2(a_11) and r. forall x_11: U_2(x_11) -> S_11(x_11). forall x_11: S_11(x_11) -> U_2(x_11).