Consider the following premises. For all x_12, x_12 will climb a mountain if and only if x_12 is a janitor. For all x_12, x_12 is a scientist or x_12 is happy. For all x_12, x_12 is not a janitor. For all x_12, if x_12 were a police officer, then x_12 is not happy. For all x_12, if x_12 were a scientist, then x_12 is climbing a mountain. Can we infer the following from them? There is at least one x_12 for which x_12 is a police officer.
 From the fact that for all x_12, x_12 will climb a mountain if and only if x_12 is a janitor, and that for all x_12, x_12 is not a janitor we can infer that for all x_12, x_12 will not climb a mountain. From the fact that for all x_12, if x_12 were a scientist, then x_12 is climbing a mountain, and that for all x_12, x_12 will not climb a mountain we can infer that for all x_12, x_12 is not a scientist. From the fact that for all x_12, x_12 is a scientist or x_12 is happy, and that for all x_12, x_12 is not a scientist we can infer that for all x_12, x_12 is happy. Finally, from the fact that for all x_12, if x_12 were a police officer, then x_12 is not happy, and that for all x_12, x_12 is happy we can infer that for all x_12, x_12 is not a police officer, which contradicts that There is at least one x_12 for which x_12 is a police officer. Therefore, the answer is no.