Consider the following premises. For all y, if y were sad, then y is sleeping. Michael is sleeping. For all y, y will sleep if and only if y is sad. Can we infer the following from them? There is at least one y for which y is sad.
 From the fact that for all y, y will sleep if and only if y is sad we can infer that for all y, if y sleeps, then y is sad. From the fact that for all y, if y sleeps, then y is sad, and that for all y, if y were sad, then y is sleeping we can infer that for all y, y will sleep if and only if y is sad. From the fact that Michael is sleeping we can infer that there is at least one y for which y will sleep. From the fact that for all y, y will sleep if and only if y is sad we can infer that for all y, if y sleeps, then y is sad. Finally, from the fact that for all y, if y sleeps, then y is sad, and that there is at least one y for which y will sleep we can infer that there is at least one y for which y is sad. Therefore, the answer is yes.