Consider the following premises. For all x_9, x_9 will play tennis. For all x_9, x_9 will play tennis if and only if x_9 will play squash. There is at least one x_9 for which if x_9 were an electrician, then x_9 is not playing squash. For all x_9, if x_9 sleeps, then x_9 is playing squash. Can we infer the following from them? There is at least one x_9 for which x_9 is not an electrician.
 From the fact that for all x_9, x_9 will play tennis if and only if x_9 will play squash we can infer that for all x_9, if x_9 plays tennis, then x_9 is playing squash. From the fact that for all x_9, x_9 will play tennis we can infer that for all x_9, x_9 will play tennis or x_9 will sleep. From the fact that for all x_9, if x_9 plays tennis, then x_9 is playing squash, that for all x_9, if x_9 sleeps, then x_9 is playing squash, and that for all x_9, x_9 will play tennis or x_9 will sleep we can infer that for all x_9, x_9 will play squash. Finally, from the fact that there is at least one x_9 for which if x_9 were an electrician, then x_9 is not playing squash, and that for all x_9, x_9 will play squash we can infer that there is at least one x_9 for which x_9 is not an electrician. Therefore, the answer is yes.