Consider the following premises. For all x_4, x_4 is not bored. For all x_4, x_4 is curious or x_4 is not a janitor. For all x_4, x_4 is bored if and only if x_4 is curious. Can we infer the following from them? There is at least one x_4 for which x_4 is a janitor.
 From the fact that for all x_4, x_4 is bored if and only if x_4 is curious, and that for all x_4, x_4 is not bored we can infer that for all x_4, x_4 is not curious. From the fact that for all x_4, x_4 is curious or x_4 is not a janitor we can infer that for all x_4, if x_4 were a janitor, then x_4 is curious. Finally, from the fact that for all x_4, if x_4 were a janitor, then x_4 is curious, and that for all x_4, x_4 is not curious we can infer that for all x_4, x_4 is not a janitor, which contradicts that There is at least one x_4 for which x_4 is a janitor. Therefore, the answer is no.