What can be inferred from the following premises in a single inference step (ignoring inferences that add new predicates or constants)? For all z, z is not a bartender. For all z, if z were a bartender, then z is listening to a song. For all z, if z listens to a song, then z is a bartender.
For all z, z will not listen to a song. For all z, z is a bartender if and only if z will listen to a song. For all z, z will listen to a song if and only if z is a bartender.