Consider the following premises. Michael is taking a plane. For all y_1, y_1 is a police officer. Can we infer the following from them? There is at least one y_1 for which y_1 will take a plane and y_1 is a police officer.
 From the fact that Michael is taking a plane we can infer that there is at least one y_1 for which y_1 will take a plane. Finally, from the fact that there is at least one y_1 for which y_1 will take a plane, and that for all y_1, y_1 is a police officer we can infer that there is at least one y_1 for which y_1 will take a plane and y_1 is a police officer. Therefore, the answer is yes.