Consider the following premises. u_4 <-> s. s <-> q_8. Can we infer u_4 -> q_8 from them? If possible, name the inference rules being used at each step.
 From s <-> q_8 we can infer s -> q_8 via biconditional elimination. From u_4 <-> s we can infer u_4 -> s via biconditional elimination. Finally, from u_4 -> s, s -> q_8 we can infer u_4 -> q_8 via transitivity. Therefore, the answer is yes.