Changes

Opening books are typically stored in two main formats:

The most advantage is that by using text form is that they are readable, understandable, and editable by humans without any special softwareand can be viewed, edited with normal text editors. 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). If we store openings "continuously" (all possible opening positions) both data size and searching time become too huge and become unacceptable for playing. They are usually missing weight values (to compare between items to know which ones are better) either. In practice, those opening books are usually very small with some lines or positions only, they cannot are hard to be used for real game playing but for testing.

* Special text formats: In 1999, [[Marc-Philippe Huget]] published a '''Book Builder''' <ref>[https://www.stmintz.com/ccc/index.php?id=44407 Web site updated and new program Book Builder] by [[Marc-Philippe Huget]], [[CCC]], February 24, 1999</ref> in conjunction with his engine [[La Dame Blanche]], a standalone open source program <ref>[http://www.quarkchess.de/ladameblanche/ Book Bilder of La Dame Blanche] by [[Marc-Philippe Huget]], hosted by [[Thomas Mayer]]</ref> to convert a [[Portable Game Notation|PGN file]] into an opening book of the format proposed by [[Kathe Spracklen]] <ref>[[Kathe Spracklen]] ('''1983'''). ''Tutorial: Representation of an Opening Tree''. [[ICGA Journal#6_1|ICCA Newsletter, Vol. 6, No. 1]]</ref>:

Binary books have some important advantages, especially for computer chess engines. Opening databases built on all positions are usually more : space-efficient , fast on accessing and overcome searching, more useful information. At the problem most simple form, they are just a conversion of above text-opening books into binary. However, the major number of binary books is built and worked with hash values from [[Transposition|transpositions]]. Often these positions are stored as hash values to allow fast access. Some opening database formats store with each position as well as some information about it. (e.g. 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). So when a chess program has to decide on a move, it will look up all positions that could arise after moving in the database and then make a decision upon the information given with each position. Depends on designs, an item may take 10 - 16 bytes. To build and/or edit those opening books, users need to use special software.