What can be inferred from the following premises in a single inference step (ignoring inferences that add new predicates or constants)? David is a doctor or John is not reading a book. If Elisabeth were a soldier, then John is reading a book. If David were a doctor, then Richard is an artist. If Richard were an artist, then Elisabeth is a soldier.
If David were a doctor, then Elisabeth is a soldier. If Richard were an artist, then John is reading a book. If John reads a book, then David is a doctor.