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 if z goes running, then z is a taxi driver. For all z, if z writes a letter, then z is running. For all z, if z were a taxi driver, then z is a janitor. For all z, if z were a janitor, then z is writing a letter.
For all z, if z were a taxi driver, then z is writing a letter. For all z, if z were a janitor, then z is running. There is at least one z for which if z goes running, then z is a janitor. There is at least one z for which if z writes a letter, then z is a taxi driver.