What can be inferred from the following premises in a single inference step (ignoring inferences that add new predicates or constants)? There is at least one z for which z is a police officer if and only if z will write a letter. For all z, if z were a writer, then z is writing a letter. For all z, if z were a police officer, then z is a writer.
For all z, if z were a police officer, then z is writing a letter. There is at least one z for which if z were a police officer, then z is writing a letter. There is at least one z for which if z writes a letter, then z is a police officer.