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