Consider the following premises. u_4 or r_4. w_4 <-> p. u_4 -> r_11. w_4 -> ~r_11. r_4 -> r_11. Can we infer p from them? If possible, name the inference rules being used at each step.
 From u_4 -> r_11, r_4 -> r_11, u_4 or r_4 we can infer r_11 via disjunction elimination. From w_4 -> ~r_11, r_11 we can infer ~w_4 via modus tollens. Finally, from w_4 <-> p, ~w_4 we can infer ~p via biconditional elimination, which contradicts p. Therefore, the answer is no.