What can be inferred from the following premises in a single inference step (ignoring inferences that add new predicates or constants)? David is an astronaut if and only if Joseph is listening to a song. Susan is a soldier if and only if Joseph is listening to a song. It is not raining. If David were an astronaut, then it is raining.
David is not an astronaut. If David were an astronaut, then Joseph is listening to a song. If Susan were a soldier, then Joseph is listening to a song. If Joseph listens to a song, then David is an astronaut. If Joseph listens to a song, then Susan is a soldier.