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