Consider the following premises. p_1. p_1 -> w_1. w -> ~w_1. Can we infer w from them? If possible, name the inference rules being used at each step.
 From p_1 -> w_1, p_1 we can infer w_1 via modus ponens. Finally, from w -> ~w_1, w_1 we can infer ~w via modus tollens, which contradicts w. Therefore, the answer is no.