Consider the following premises. For all x_3, x_3 is a lawyer or x_3 is not a janitor. For all x_3, if x_3 were a lawyer, then x_3 is a janitor. There is at least one x_3 for which x_3 is not a lawyer. Can we infer the following from them? There is at least one x_3 for which x_3 is not a janitor.
 From the fact that for all x_3, x_3 is a lawyer or x_3 is not a janitor we can infer that for all x_3, if x_3 were a janitor, then x_3 is a lawyer. From the fact that for all x_3, if x_3 were a janitor, then x_3 is a lawyer, and that for all x_3, if x_3 were a lawyer, then x_3 is a janitor we can infer that for all x_3, x_3 is a janitor if and only if x_3 is a lawyer. Finally, from the fact that for all x_3, x_3 is a janitor if and only if x_3 is a lawyer, and that there is at least one x_3 for which x_3 is not a lawyer we can infer that there is at least one x_3 for which x_3 is not a janitor. Therefore, the answer is yes.