Consider the following premises. ~q_14. t_2 <-> q_8. q_8 <-> u_3. t_2 <-> q_14. Can we infer ~u_3 from them? If possible, name the inference rules being used at each step.
 From t_2 <-> q_14, ~q_14 we can infer ~t_2 via biconditional elimination. From t_2 <-> q_8, ~t_2 we can infer ~q_8 via biconditional elimination. From q_8 <-> u_3 we can infer u_3 -> q_8 via biconditional elimination. Finally, from u_3 -> q_8, ~q_8 we can infer ~u_3 via modus tollens. Therefore, the answer is yes.