Consider the following premises. p -> q_4. t <-> q_4. Can we infer ~(p -> t) from them? If possible, name the inference rules being used at each step.
 From t <-> q_4 we can infer q_4 -> t via biconditional elimination. Finally, from p -> q_4, q_4 -> t we can infer p -> t via transitivity, which contradicts ~(p -> t). Therefore, the answer is no.