What can be inferred from the following premises in a single inference step (ignoring inferences that add new predicates or constants)? p_8 <-> s_1. s_1 <-> q_13. ~q_13. ~p_8 -> t.
p_8 -> s_1. s_1 -> q_13. s_1 -> p_8. q_13 -> s_1. ~s_1.