Consider the following premises. For all x, if x were a janitor, then x is an electrician. For all x, if x were an electrician, then x is a janitor. For all x, if x were an electrician, then x is a janitor. Can we infer the following from them? There is at least one x for which the fact that x were an electrician does not imply that x is a janitor.
 From the fact that for all x, if x were a janitor, then x is an electrician, and that for all x, if x were an electrician, then x is a janitor we can infer that for all x, x is a janitor if and only if x is an electrician. From the fact that for all x, x is a janitor if and only if x is an electrician we can infer that for all x, if x were a janitor, then x is an electrician. From the fact that for all x, if x were an electrician, then x is a janitor, and that for all x, if x were a janitor, then x is an electrician we can infer that for all x, x is an electrician if and only if x is a janitor. Finally, from the fact that for all x, x is an electrician if and only if x is a janitor we can infer that for all x, if x were an electrician, then x is a janitor, which contradicts that There is at least one x for which the fact that x were an electrician does not imply that x is a janitor. Therefore, the answer is no.