What can be inferred from the following premises in a single inference step (ignoring inferences that add new predicates or constants)? S_11(b) -> u_4. u_4 <-> q_15. forall x_11: U(x_11) or S_11(x_11). ~U(b) or r_7. ~q_15.
u_4 -> q_15. q_15 -> u_4. ~u_4.