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_9 <-> q_9. q_9 or ~s.
s -> q_9 can be inferred via the rewriting rule. p_9 -> q_9 can be inferred via the biconditional elimination rule. q_9 -> p_9 can be inferred via the biconditional elimination rule.