Specify relational calculus expression for the following descriptions on the Library database schema shown in Figure 4.6.

a) Retrieve Publishers name and phone number whose books where borrowed from Baltimore Branch.

b) List the book title, book id and branch name with less than 10 copies

c) List customer card number, customer name, branch name and book title for books which are currently on loan.

BOOK Book id Title Publisher_name BOOK_AUTHORS Book idAuthor name PUBLISHER Name Address Phone BOOK COPIES Book_idBranch_id| No_of_copies BOOK LOANS Book id Branch id Card no Date out Due_date LIBRARY BRANCH Branch_id Branch_name Address BORROWER Figure 4.6 A relational database schema for a LIBRARY database. Card no Name Address Phone