Consider the following premises. p -> w. u_4 <-> p. w -> p. Can we infer w -> u_4 from them?
 From w -> p, p -> w we can infer w <-> p. From u_4 <-> p we can infer p -> u_4. From w <-> p we can infer w -> p. Finally, from w -> p, p -> u_4 we can infer w -> u_4. Therefore, the answer is yes.