What can be inferred from the following premises in a single inference step (ignoring inferences that add new predicates or constants)? Name the inference rule being used: p_17 <-> q_17. ~q_17. ~s. u -> s.
~u can be inferred via the modus tollens rule. ~q_17 and ~s can be inferred via the conjunction rule. ~s and ~q_17 can be inferred via the conjunction rule. p_17 -> q_17 can be inferred via the biconditional elimination rule. q_17 -> p_17 can be inferred via the biconditional elimination rule. ~p_17 can be inferred via the biconditional elimination rule.