What can be inferred from the following premises in a single inference step (ignoring inferences that add new predicates or constants)? For all z, if z works, then z is happy. For all z, z will work or z will play squash. There is at least one z for which z will play squash if and only if z is happy.
There is at least one z for which if z plays squash, then z is happy. There is at least one z for which if z were happy, then z is playing squash.