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 x for which if x were a janitor, then x is a doctor. For all x, x is a doctor if and only if x is a janitor.
For all x, if x were a doctor, then x is a janitor. For all x, if x were a janitor, then x is a doctor.