Consider the following premises. For all x_13, if x_13 makes tea, then x_13 is sleeping. William is sleeping if and only if William is a janitor. William is not sleeping. For all x_13, if x_13 were a janitor, then x_13 is making tea. Can we infer the following from them? William is a janitor.
 From the fact that for all x_13, if x_13 were a janitor, then x_13 is making tea, and that for all x_13, if x_13 makes tea, then x_13 is sleeping we can infer that for all x_13, if x_13 were a janitor, then x_13 is sleeping. From the fact that for all x_13, if x_13 were a janitor, then x_13 is sleeping we can infer that if William were a janitor, then William is sleeping. From the fact that William is sleeping if and only if William is a janitor we can infer that if William sleeps, then William is a janitor. From the fact that if William were a janitor, then William is sleeping, and that if William sleeps, then William is a janitor we can infer that William is a janitor if and only if William is sleeping. Finally, from the fact that William is a janitor if and only if William is sleeping, and that William is not sleeping we can infer that William is not a janitor, which contradicts that William is a janitor. Therefore, the answer is no.