Consider the following premises. For all x_7, x_7 will play tennis if and only if x_7 is a police officer. For all x_7, if x_7 sleeps, then x_7 is not fast. For all x_7, x_7 will not play tennis. For all x_7, x_7 is a police officer or x_7 is fast. Can we infer the following from them? There is at least one x_7 for which x_7 will sleep.
 From the fact that for all x_7, x_7 will play tennis if and only if x_7 is a police officer, and that for all x_7, x_7 will not play tennis we can infer that for all x_7, x_7 is not a police officer. From the fact that for all x_7, x_7 is a police officer or x_7 is fast, and that for all x_7, x_7 is not a police officer we can infer that for all x_7, x_7 is fast. Finally, from the fact that for all x_7, if x_7 sleeps, then x_7 is not fast, and that for all x_7, x_7 is fast we can infer that for all x_7, x_7 will not sleep, which contradicts that There is at least one x_7 for which x_7 will sleep. Therefore, the answer is no.