What can be inferred from the following premises in a single inference step (ignoring inferences that add new predicates or constants)? ~q_13. ~p_8 -> t. s_4 <-> q_13. p_8 <-> s_4.
s_4 -> q_13. p_8 -> s_4. q_13 -> s_4. s_4 -> p_8. ~s_4.