Consider the following premises. For all x_7, x_7 will work if and only if x_7 is a writer. For all x_7, x_7 is not a writer. For all x_7, x_7 will work or x_7 is a police officer. Can we infer the following from them? If we can, name the inference rule being used: For all x_7, x_7 is a police officer.
 From the fact that for all x_7, x_7 will work if and only if x_7 is a writer we can infer that for all x_7, if x_7 works, then x_7 is a writer via universal biconditional elimination. From the fact that for all x_7, if x_7 works, then x_7 is a writer, and that for all x_7, x_7 is not a writer we can infer that for all x_7, x_7 will not work via universal modus tollens. Finally, from the fact that for all x_7, x_7 will work or x_7 is a police officer, and that for all x_7, x_7 will not work we can infer that for all x_7, x_7 is a police officer via universal disjunctive syllogism. Therefore, the answer is yes.