Consider the following premises. For all y_2, y_2 will play squash. There is at least one y_2 for which y_2 is an electrician if and only if y_2 is a cashier. For all y_2, y_2 will read a book. For all y_2, if y_2 were a cashier, then y_2 is not playing squash. Can we infer the following from them? There is at least one y_2 for which y_2 is not an electrician.
 From the fact that for all y_2, y_2 will play squash, and that for all y_2, y_2 will read a book we can infer that for all y_2, y_2 will play squash and y_2 will read a book. From the fact that for all y_2, y_2 will play squash and y_2 will read a book we can infer that for all y_2, y_2 will play squash. From the fact that for all y_2, if y_2 were a cashier, then y_2 is not playing squash, and that for all y_2, y_2 will play squash we can infer that for all y_2, y_2 is not a cashier. Finally, from the fact that there is at least one y_2 for which y_2 is an electrician if and only if y_2 is a cashier, and that for all y_2, y_2 is not a cashier we can infer that there is at least one y_2 for which y_2 is not an electrician. Therefore, the answer is yes.