What can be inferred from the following premises in a single inference step (ignoring inferences that add new predicates or constants)? p_7 <-> s_4. t_2 <-> s_4. q_7. p_7 -> ~q_7.
~p_7. p_7 -> s_4. t_2 -> s_4. s_4 -> p_7. s_4 -> t_2.