Consider the following premises. For all y_2, if y_2 were an artist, then y_2 is working. For all y_2, if y_2 works, then y_2 is an artist. Can we infer the following from them? If we can, name the inference rule being used: There is at least one y_2 for which the fact that y_2 were an artist does not imply that y_2 is working.
 From the fact that for all y_2, if y_2 works, then y_2 is an artist, and that for all y_2, if y_2 were an artist, then y_2 is working we can infer that for all y_2, y_2 will work if and only if y_2 is an artist via universal biconditional introduction. Finally, from the fact that for all y_2, y_2 will work if and only if y_2 is an artist we can infer that for all y_2, if y_2 were an artist, then y_2 is working via universal biconditional elimination, which contradicts that There is at least one y_2 for which the fact that y_2 were an artist does not imply that y_2 is working. Therefore, the answer is no.