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_idTitle Publisher name BOOK_AUTHORS Book idAuthor_name PUBLISHER Name Address Phone BOOK COPIES Book id Branch id O of copies BOOK LOANS Book idBranch ird 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