In the schema declaration, we have declared two names: stock and on loan. Stock is the set of books held by the library. The notation P S means Powerset S. That is, the type of stock is defined as the set of sets of books. On loan refers to the set of books that have been lent out. Each member of the set is mapped to a known borrower. The predicate dom onLoad subset stock denotes that the books on loan are a subset of existing stock. The general term dom R represents the.