Consider the following premises. q -> u_4. t_2 -> u_4. ~p_16 or t_2. t_4 <-> u_4. p_16 or q. Can we infer ~t_4 from them? If possible, name the inference rules being used at each step.
 From p_16 or q, ~p_16 or t_2 we can infer q or t_2 via resolution. From q -> u_4, t_2 -> u_4, q or t_2 we can infer u_4 via disjunction elimination. From t_4 <-> u_4 we can infer u_4 -> t_4 via biconditional elimination. Finally, from u_4 -> t_4, u_4 we can infer t_4 via modus ponens, which contradicts ~t_4. Therefore, the answer is no.