What can be inferred from the following premises in a single inference step (ignoring inferences that add new predicates or constants)? Richard is driving a car. If Robert listens to a song, then Robert is a police officer. For all x_12, if x_12 were a police officer, then x_12 is listening to a song. If Robert listens to a song, then Richard is not driving a car.
Robert is not listening to a song.