Consider the following premises. p <-> w. ~t. s <-> t. w <-> s. Can we infer ~p from them? If possible, name the inference rules being used at each step.
 From s <-> t, ~t we can infer ~s via biconditional elimination. From w <-> s, ~s we can infer ~w via biconditional elimination. Finally, from p <-> w, ~w we can infer ~p via biconditional elimination. Therefore, the answer is yes.