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 -> q_15. p_2 or q. ~q_15. q_15 -> q.
~q can be inferred via the modus tollens rule. ~q -> p_2 can be inferred via the rewriting rule. q <-> q_15 can be inferred via the biconditional introduction rule. q_15 <-> q can be inferred via the biconditional introduction rule.