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 were a scientist, then z is happy. For all z, if z were happy, then z is a scientist. For all z, z will listen to a song if and only if z is happy. For all z, z will not listen to a song.
For all z, z is a scientist if and only if z is happy. For all z, z is happy if and only if z is a scientist. For all z, if z listens to a song, then z is happy. For all z, if z were happy, then z is listening to a song. For all z, z is not happy.