Consider the following premises. For all x, x is an artist or x is not a janitor. There is at least one x for which x is a janitor or x is not an artist. Can we infer the following from them? There is at least one x for which if x were an artist, then x is a janitor.
 From the fact that for all x, x is an artist or x is not a janitor we can infer that for all x, if x were a janitor, then x is an artist. Finally, from the fact that there is at least one x for which x is a janitor or x is not an artist we can infer that there is at least one x for which if x were an artist, then x is a janitor. Therefore, the answer is yes.