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#Pgn chess books software#
#Pgn chess books code#

#Pgn chess books code#

Those engines need both opening book code and book data to run Some engines use external books, some others integrate books inside their codes. Engines: They can directly use opening books to make move.It is true that by using this way of database generation some severe errors might by copied as well, but usually the chess programs are set to stop playing according to the book if a position occurred less than a certain number times before.Ĭhess engines can be used to evaluate positions in a book opening tree to rank them, and/or decide to stop or expand. drawn games only, GM games only, etc) and then up to a certain depth store all positions in the opening database. Another option is to first automatically generate a database and then fine-tune it manually.Īnother option is to select a number of games (the type of which will affect the openings played: e.g. Then the opening style will probably be chosen to be difficult and dangerous for the opponent. This is often the case if a chess program is about to play an important game against a grandmaster. If the opening database designer has some special preference of a certain opening line, he might create it fully manually. But to achieve this there are two main ways. To build and/or edit those opening books, users need to use special software.Īll in all the information stored in an opening database should guide the chess game into a type of middle game in which the chess program proves itself most successful. So when a chess program has to decide on a move, it will look up (by using binary-search) using the hash value of the current position to collect all information come with that hash value and then make a decision upon it. Items of a book should be sorted by their hash. For example, PolyGlot uses 16 bytes for each item, including hash, move, weight, learning values. To save space those extra information typically about 2-8 bytes. Often each position is stored as a hash value (8 bytes) and some extra information such as the number of times occurred, number of games won by white/black / drawn with this position, average/maximum Elo of players playing to this opening position, chess program's success with the position. However, the major number of top books is built and worked with hash values from transpositions.

#Pgn chess books software#

At the most simple form, they are just a conversion of above text-opening books into binary, in the ready form for software and save text-binary converting steps.

Special text formats: In 1999, Marc-Philippe Huget published a Book Builder in conjunction with his engine La Dame Blanche, a standalone open source program to convert a PGN file into an opening book of the format proposed by Kathe Spracklen :īinary books have some important advantages, especially for computer chess engines: space-efficient, fast on accessing and searching, more useful information.

PGN: Opening lines are stored as individual games.

EPD: They are the last positions of opening lines.

They are stored in typical ways for games and positions: In practice, those opening books are usually very small with some lines or positions only, they are hard to be used for real game playing but for testing. They are usually missing weight values (to compare between items to know which ones are better) either. If we store openings "continuously" (all possible opening positions) both data size and searching time become too huge and unacceptable for playing. However, the main disadvantage is that they may take too much space as well as time for searching since an item may take from 50 bytes (for FEN strings) to hundreds of bytes (for PGN text). The most advantage by using text form is that they are readable, understandable, and editable by humans and can be viewed, edited with normal text editors. Opening books are typically stored in two main formats: As book moves can be chosen randomly, whereas searches are more or less deterministic.

Provide variety: there already exists a lot of literature about different opening lines.

It may lose temporarily material for long term advantage. Provide a higher quality of play: Searching even with large depths can't see deep tactics, strategy, compensation.In contrast, opening books can play opening moves almost instantly without searching nor heavy computing and help to save time. Save time: Chess programs could use search from the beginning and look through all possible continuations in detail to find the best next move, but as this is quite time-consuming.