The giant American book retailer Barnes & Noble Inc. has joined with the online education company notHarvard.com to establish an Internet-based university offering free tuition in what critics say is a sales and marketing gimmick. The two companies said the virtual university will offer free online courses to customers of Barnes & Noble through its web site beginning this summer. Under the partnership agreement, Barnes & Noble will become the primary distributor of notHarvard.com's eduCommerce course and software materials. Courses will be based upon books carried by Barnes & Noble and the company is inviting authors of those books to become "university instructors" by hiring them to publish additional content in electronic form.