It is not the case that b has been borrowed. (Provided it has not been lost :-)c) Book b is on the shelf
There exists a person and two non-equal books such that the person borrowed one and the other.d) Person p has borrowed at least two books.
For any book and two non-equal persons, if they borrowed this book, then False (contradiction, 0 = 1, p not equal to p, etc.)e) No book has been borrowed by more than one person.