The Chess-DB.com endgame tablebases are proprietary-implemented WDL (win/draw/lose) bitbases and DTM tablebases. Most of the work we are doing so far is on the WDL generation, indexing and compression.

Endgame Databases Chess endgame databases, while of important theoretical interest, have yet to make a significant impact in tournament chess. In the game of checkers, however, endgame databases have played a pivotal role in the success of our World Championship challenger program Chinook. Consequently, we are interested in building databases consisting of hundreds of billions of positions.

Since database positions arise frequently in Chinook's search trees, the databases must be accessible in real-time. This does not yet happen in chess. The following links show the number of positions in checkers: • • • • Chinook has perfect information for all checker positions involving 8 or fewer pieces on the board, a total of 443,748,401,247 positions. These databases are now available for download! Note that some of the following files are large. The total download size is almost 2.7 GB. Unzipped size is 5.6 GB.

If you prefer CDs, please contact (we have to charge a nominal fee to cover costs). Download the databases: • (ZIP) • (ZIP) • (ZIP) • (ZIP) • (ZIP) • (ZIP) • (ZIP) • (ZIP) • (ZIP) • (ZIP) • (ZIP) • (ZIP) • (ZIP) • (ZIP) • (ZIP) • (ZIP) • (ZIP) • (ZIP) • (ZIP) • (ZIP) • (ZIP). Note that this code isn't as 'nice' as it should be.

Perfect endgame play (1) Endgame databases are a special took used by chess playing programs to increase playing strength and analytical capabilities. They are fully analysed endgames for which the program has perfect knowledge – it knows the status of every single legal position that is possible with a given material configuration. Positions with the attacking side on the move are circles, the defender-to-move positions are squares And this, in a nutshell, is how it works: first you define the material you want to analyse, e.g. King and queen vs king and rook. Then you generate every legal position that is possible with the given material. Then you mark all positions in which one side is mated with a zero.

Then you mark all positions in which the attacking side can achieve a zero-position in one move with a one. Then you mark all positions in which every legal move of the defending side leads to a position marked one, and mark it two. Then you mark all positions in which the attacker can achieve a position marked two in one move with a three.

And this et cetera can run into the millions and billions. History One of the first endgames that was exhaustively calculated was the four-piece ending queen vs rook.

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It was done by Ken Thompson back in the early ninteen eighties. He generated every legal position with K+Q vs K+R – 1,900,000 in all – and working backwards from mates created a list in which every position contained information with the distance to mate (the longest was 61 moves). A program that has access to such an 'endgame database' – today the term 'tablebase' is more commonly used – plays the endgame with absolute perfection – 'as well as god', Thompson once quipped. The four-piece ending queen vs rook was the first important endgame to be solved in this way. And it was surprisingly difficult to play. Many GMs were not able to win it against the perfect defence of the computer, so for example Walter Browne during a tournament in the 1980s, when he lost a $100 bet by not being able to capture the rook against Thompson's database. Frederic Friedel had a lot of fun with this first endgame database: at one tournament he offered $10 to anyone who could win with the queen.

One of the players dragged GM Artur Jussupow to take on the computer – and had to shell out the ten dollars. At one event he had Kasparov and Karpov consulting while trying to overcome the computer – they too failed.

And once, when the 14-year-old Peter Leko was staying at the Friedels' house, Frederic challenged him. Peter wasn't able to do it either. BUT: the next morning at breakfast he said he had found the strategy in the night, and proved it by easily winning test positions against the computer. The lad had actually worked it out in his head, while lying in bed in the dark. Even in practical play sometimes top GMs can have their problems. This is what happened at the FIDE World Championship 2001 in Moscow: in the round five playoffs Peter Svidler reached a Queen vs Rook position against Boris Gelfand.