Consider the following premises. For all x_9, x_9 is not an electrician. For all x_9, x_9 will play tennis if and only if x_9 is an electrician. There is at least one x_9 for which x_9 will play tennis if and only if x_9 is a scientist. Can we infer the following from them? For all x_9, x_9 is a scientist.
 From the fact that there is at least one x_9 for which x_9 will play tennis if and only if x_9 is a scientist we can infer that there is at least one x_9 for which if x_9 were a scientist, then x_9 is playing tennis. From the fact that for all x_9, x_9 will play tennis if and only if x_9 is an electrician, and that for all x_9, x_9 is not an electrician we can infer that for all x_9, x_9 will not play tennis. Finally, from the fact that there is at least one x_9 for which if x_9 were a scientist, then x_9 is playing tennis, and that for all x_9, x_9 will not play tennis we can infer that there is at least one x_9 for which x_9 is not a scientist, which contradicts that For all x_9, x_9 is a scientist. Therefore, the answer is no.