My guess is that the book will not cover AJAX I think it will use AJAX as a way to show examples. But we should wait for the answer.
If AJAX is not covered on this book from its fundamentals I would like to ask if Sas has any preference for any AJAX book or she can recommend me any book to begin with AJAX.
The book is an introduction to all things XML, including Ajax.
The book does cover the fundamentals of the Ajax approach. There is one chapter on DOM scripting (required for Ajax) as well as another on Ajax itself. There are also chapters on XSLT which can be used as part of Ajax.
The chapter on Ajax will give you a taste for the approach and takes you through several examples. It also lists some scripting libraries and some of the issues that might arise when using Ajax.