 |
Web Hosting by Netfirms | Free Domain Names by Netfirms |
|
|
|
ChessVU uses the ECO codes as main opening keys. The reason is that they are stored in the header data, and therefore allow easy access, filtering and sorting of the games. Other solutions would require auxiliary files (like ChessBase .cpo, .cko etc.). ECO codes have the form "XDD" (500 values) or the form "XDD/DD" where the "X" s a letter from "A" to "E" and the "D" positions are digits; this is used for an opening designation from the five volume Encyclopedia of Chess Openings. Because 500 values are not enough, ChessVU allows the “refining” of ECO codes, by adding the /DD, where DD can be 99 down to 00. In this way there are 50000 possible opening keys. The XDD/DD code is supported by the CBF and PGN format. While the XDD code is universally accepted, the /DD extension is seldom used. ChessVU uses this extension in a “private” way, that is the extension has no relationship with the extension given by Encyclopedia of Chess Openings or others Opening Books.
ChessVU refines a book in the following way. Each node of the book position tree having a certain importance is given a /DD code (main node). The importance threshold can be set by Options (e.g. a node must have at least N games in the line and at least M branches). The position tree is explored, and the position most frequently reached is given the /99 code. The same happens to all the positions originating from the same main node. The tree is then explored backwards, and all the main nodes (and related positions) are given a descending /DD code. The book can be unrefined, that is all the nodes can be set back to the XDD value (without extension).
It is possible to create a CBK file for a specific opening CBF data base (like C89.CBF), and to refine it. At the end of the refining process, the data base games will be sorted in the order given by the refined keys, starting from C89/99 down to C89/00. All the games that have been considered are marked. Please note that, depending on the book settings (depth, N games in the line, M branches) and on the data base size, a “leaf” position might correspond to more than one game (that is, the depth of the tree is not enough to separate the games). In this case only one game will be marked, all the others will remain unmarked (and not sorted). For the same reason, it may happen that a line in the book shows N games, but only M<N are exported when <Browse book: Load games> function is used. To increase the marked games, increase the book depth. In any case, the CBF file games are not directly classified; they must be classified by command (in this way all the games will be classified).
Refine/unrefine book