Houdini Opening Book - Optimized for Houdini Chess Engine Latest chess theory approved in millions of advanced chess games and matches of top human players Over 65 million positions Developed especially for the Houdini engine family, but can be used with any other engine Includes chess trees (positional databases) containing computer evaluations of the moves in the book and statistics showing their popularity in human games and in correspondence play The book is specially designed to use all the advantages of navigation in multi-column tree view of the Aquarium GUI