Consider the following premises. For all z, z is not an astronaut. For all z, z is a police officer if and only if z is an astronaut. Can we infer the following from them? If we can, name the inference rule being used: For all z, z is not a police officer.
 From the fact that for all z, z is a police officer if and only if z is an astronaut we can infer that for all z, if z were a police officer, then z is an astronaut via universal biconditional elimination. Finally, from the fact that for all z, if z were a police officer, then z is an astronaut, and that for all z, z is not an astronaut we can infer that for all z, z is not a police officer via universal modus tollens. Therefore, the answer is yes.