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 z for which z will not take a plane. For all z, z will sleep or z will not take a plane. For all z, z will take a plane or z will not sleep.
For all z, if z takes a plane, then z is sleeping. For all z, if z sleeps, then z is taking a plane.