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_11 or s_2. w or ~q_11. s_2 <-> w.
q_11 -> w can be inferred via the rewriting rule. s_2 -> w can be inferred via the biconditional elimination rule. w -> s_2 can be inferred via the biconditional elimination rule.