Consider the following premises. r_3 or ~s_2. q_8 <-> r_3. ~t. t <-> q_8. Can we infer s_2 from them? If possible, name the inference rules being used at each step.
 From r_3 or ~s_2 we can infer s_2 -> r_3 via rewriting. From t <-> q_8, ~t we can infer ~q_8 via biconditional elimination. From q_8 <-> r_3, ~q_8 we can infer ~r_3 via biconditional elimination. Finally, from s_2 -> r_3, ~r_3 we can infer ~s_2 via modus tollens, which contradicts s_2. Therefore, the answer is no.