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 y for which y will not play squash. For all y, if y were a janitor, then y is playing squash. For all y, if y plays squash, then y is a janitor.
There is at least one y for which y is not a janitor. For all y, y is a janitor if and only if y will play squash. For all y, y will play squash if and only if y is a janitor.