What can be inferred from the following premises in a single inference step (ignoring inferences that add new predicates or constants)? If it is cloudy, then David is playing squash. David is not playing squash. William is reading a book if and only if it is raining. If William reads a book, then it is cloudy.
It is not cloudy. If William reads a book, then it is raining. If it rains, then William is reading a book.