What is the name of the fourth book in 'The Inheritance Cycle' by Christopher Paolini?

Well, the candidates for the title are 'Empire', 'Eridor', 'Ending', 'Glaedr' and 'Aleala'. If you want more info on the titles go to: http://www.shurtugal.com/wiki/index.php/Book_IV_%28Theories%29#Title