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_8 or ~q_2. q_13 <-> q_8. p_13 <-> q_13. ~p_13.
q_2 -> q_8 can be inferred via the rewriting rule. q_13 -> q_8 can be inferred via the biconditional elimination rule. p_13 -> q_13 can be inferred via the biconditional elimination rule. q_8 -> q_13 can be inferred via the biconditional elimination rule. q_13 -> p_13 can be inferred via the biconditional elimination rule. ~q_13 can be inferred via the biconditional elimination rule.