Consider the following premises. ~p_10. p_10 <-> q_10. q_10 -> w. w -> s. s -> q_10. Can we infer w from them? If possible, name the inference rules being used at each step.
 From p_10 <-> q_10, ~p_10 we can infer ~q_10 via biconditional elimination. From w -> s, s -> q_10 we can infer w -> q_10 via transitivity. From w -> q_10, q_10 -> w we can infer w <-> q_10 via biconditional introduction. Finally, from w <-> q_10, ~q_10 we can infer ~w via biconditional elimination, which contradicts w. Therefore, the answer is no.