Consider the following premises. p_12 or ~q_2. p_12 -> q. p_18 <-> q_2. u_3 -> p_18. Can we infer ~(u_3 -> q) from them?
 From p_18 <-> q_2 we can infer p_18 -> q_2. From p_12 or ~q_2 we can infer q_2 -> p_12. From p_18 -> q_2, q_2 -> p_12 we can infer p_18 -> p_12. From p_18 -> p_12, p_12 -> q we can infer p_18 -> q. Finally, from u_3 -> p_18, p_18 -> q we can infer u_3 -> q, which contradicts ~(u_3 -> q). Therefore, the answer is no.