What can be inferred from the following premises in a single inference step (ignoring inferences that add new predicates or constants)? For all x, if x were a police officer, then x is a janitor. For all x, x is a janitor. For all x, if x were a janitor, then x is a police officer.
For all x, x is a police officer. For all x, x is a police officer if and only if x is a janitor. For all x, x is a janitor if and only if x is a police officer.