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: ~q_15. q <-> q_15. s. q -> q_15.
~q can be inferred via the modus tollens rule. ~q_15 and s can be inferred via the conjunction rule. s and ~q_15 can be inferred via the conjunction rule. q -> q_15 can be inferred via the biconditional elimination rule. q_15 -> q can be inferred via the biconditional elimination rule. ~q can be inferred via the biconditional elimination rule.