What can be inferred from the following premises in a single inference step (ignoring inferences that add new predicates or constants)? For all x_10, if x_10 were a janitor, then x_10 is working. For all x_10, if x_10 works, then x_10 is a janitor. Richard is not working.
For all x_10, x_10 is a janitor if and only if x_10 will work. For all x_10, x_10 will work if and only if x_10 is a janitor.