What can be inferred from the following premises in a single inference step (ignoring inferences that add new predicates or constants)? For all x_4, if x_4 were a janitor, then x_4 is working. For all x_4, if x_4 works, then x_4 is an office clerk. For all x_4, if x_4 were an office clerk, then x_4 is a janitor. Thomas is not a janitor.
For all x_4, if x_4 were a janitor, then x_4 is an office clerk. For all x_4, if x_4 works, then x_4 is a janitor. For all x_4, if x_4 were an office clerk, then x_4 is working.