Nalimov Tablebases (3 4 5 6) (more Tablebases) Setup ((NEW)) Free
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Syzygy tablebases allow perfect play with up to 7 pieces, both with and without the fifty-move drawing rule, i.e., they allow winning all won positions and bringing all drawn positions over the fifty-move line.
Tablebases are generated by retrograde analysis, working backward from a checkmated position. By 2005, all chess positions with up to six pieces, including the two kings, had been solved. By August 2012, tablebases had solved chess for almost every position with up to seven pieces, but the positions with a lone king versus a king and five pieces were omitted because they were considered to be "rather obvious." These positions were included by August 2018. As of 2023[update], work is still underway to solve all eight-piece positions.
The solutions have profoundly advanced the chess community's understanding of endgame theory. Some positions which humans had analyzed as draws were proven to be winnable; in some cases the tablebase analysis could find a mate in more than five hundred moves, far beyond the horizon of humans, and beyond the capability of a computer during play. For this reason, tablebases also called into question the 50-move rule, since many positions are now seen to exist that would be a win for one side but are drawn because of the 50-move rule; initially, as individual cases were found, exceptions to the rule were introduced, but when more extreme cases were later discovered, the exceptions were removed. Tablebases provide a powerful analytical tool, enhancing competitive play and facilitating the composition of endgame studies.
While endgame tablebases exist for other board games, such as checkers, nine men's morris, and some chess variants, the term endgame tablebase is assumed to refer to the chess tablebase by default.
Ken Thompson and others helped extend tablebases to cover all four- and five-piece endgames, including in particular KBBKN, KQPKQ, and KRPKR. Lewis Stiller published a thesis with research on some six-piece tablebase endgames in 1991.
The tablebases of all endgames with up to seven pieces are available for free download, and may also be queried using web interfaces (see the external links below). Nalimov tablebase requires more than one terabyte of storage space.
Haworth has discussed two other metrics, namely "depth to zeroing-move" (DTZ) and "depth by the rule" (DTR). A zeroing-move is a move which resets the move count to zero under the fifty-move rule, i.e. mate, a capture, or a pawn move. These metrics support the fifty-move rule, but DTR tablebases have not yet been computed. 7-man DTZ tablebases were made publicly available in August 2018.
A four-piece tablebase must rely on three-piece tablebases that could result if one piece is captured. Similarly, a tablebase containing a pawn must be able to rely on other tablebases that deal with the new set of material after pawn promotion to a queen or other piece. The retrograde analysis program must account for the possibility of a capture or pawn promotion on the previous move.
The same ambiguity exists for the en passant capture, since the possibility of en passant depends on the opponent's previous move. However, practical applications of en passant occur frequently in pawn endgames, so tablebases account for the possibility of en passant for positions where both sides have at least one pawn.
Bleicher has designed a commercial program called "Freezer," which allows users to build new tablebases from existing Nalimov tablebases with a priori information. The program could produce a tablebase for positions with seven or more pieces with blocked pawns, even before tablebases for seven pieces became available.
In correspondence chess, a player may consult a chess computer for assistance, provided that the etiquette of the competition allows this. Some correspondence organizations draw a distinction in their rules between utilizing chess engines which calculate a position in real time and the use of a precomputed database stored on a computer. Use of an endgame tablebase might be permitted in a live game even if engine use is forbidden. Players have also used tablebases to analyze endgames from over-the-board play after the game is over. A six-piece tablebase (KQQKQQ) was used to analyze the endgame that occurred in the correspondence game Kasparov versus The World.
Competitive players need to know that some tablebases ignore the fifty-move rule. According to that rule, if fifty moves have passed without a capture or a pawn move, either player may claim a draw. FIDE changed the rules several times, starting in 1974, to allow one hundred moves for endgames where fifty moves were insufficient to win. In 1988, FIDE allowed seventy-five moves for KBBKN, KNNKP, KQKBB, KQKNN, KRBKR, and KQPKQ with the pawn on the seventh rank, because tablebases had uncovered positions in these endgames requiring more than fifty moves to win. In 1992, FIDE canceled these exceptions and restored the fifty-move rule to its original standing. Thus a tablebase may identify a position as won or lost, when it is in fact drawn by the fifty-move rule. Such a position is sometimes termed a "cursed win" (where mate can be forced, but it runs afoul of the 50-move rule), or a "blessed loss" from the perspective of the other player.
In 2013, ICCF changed the rules for correspondence chess tournaments starting from 2014; a player may claim a win or draw based on six-man tablebases. In this case the fifty-move rule is not applied, and the number of moves to mate is not taken into consideration. In 2020, this was increased to seven-man tablebases.
Haworth has designed a tablebase that produces results consistent with the fifty-move rule. However most tablebases search for the theoretical limits of forced mate, even if it requires several hundred moves.
Another drawback is that tablebases require a lot of memory to store the many thousands of positions. The Nalimov tablebases, which use advanced compression techniques, require 7.05 GB of hard disk space for all 5-piece endings. The 6-piece endings require approximately 1.2 TB. The 7-piece Lomonosov tablebase requires 140 TB of storage space. Some computers play better overall if their memory is devoted instead to the ordinary search and evaluation function. Modern engines analyze far enough ahead conventionally to handle the elementary endgames without needing tablebases (i.e., without suffering from the horizon effect). It is only in more complicated endgames that tablebases will have any significant effect on an engine's performance.
Syzygy tablebases were developed by Ronald de Man, released in April 2013, in a form optimized for use by a chess program during search. This variety consists of two tables per endgame: a smaller WDL (win/draw/loss) table which contains knowledge of the 50-move rule, and a larger DTZ table (distance to zero ply, i.e., pawn move or capture). The WDL tables were designed to be small enough to fit on a solid-state drive for quick access during search, whereas the DTZ form is for use at the root position to choose the game-theoretically quickest distance to resetting the 50-move rule while retaining a winning position, instead of performing a search. Syzygy tablebases are available for all 6-piece endings, and are now supported by many top engines, including Komodo, Deep Fritz, Houdini, and Stockfish. Since August 2018, all 7-piece Syzygy tables are also available.
In contexts where the fifty-move rule may be ignored, tablebases have answered longstanding questions about whether certain combinations of material are wins or draws. The following interesting results have emerged:
Since many composed endgame studies deal with positions that exist in tablebases, their soundness can be checked using the tablebases. Some studies have been proved unsound by the tablebases. That can be either because the composer's solution does not work, or else because there is an equally effective alternative that the composer did not consider. Another way tablebases cook studies is a change in the evaluation of an endgame. For instance, the endgame with a queen and bishop versus two rooks was thought to be a draw, but tablebases proved it to be a win for the queen and bishop, so almost all studies based on this endgame are unsound.
While tablebases have cooked some studies, they have assisted in the creation of other studies. Composers can search tablebases for interesting positions, such as zugzwang, using a method called data mining. For all three- to five-piece endgames and pawnless six-piece endgames, a complete list of mutual zugzwangs has been tabulated and published.
The only 7 piece site I heard about is , and upon registration I am able to setup various positions with 2-6 pieces . However as soon as I setup a position with 7 piece, I get an error about service not being avaiable. Has anyone had better luck or know of any other site with 7 pieces tablebases?
The first ending tablebases - for all 4-piece endgames - were built by the end of the 80-s. In the beginning of the 90-s, the same task was done for 5-pieces. In 2005, 6-piece endings were solved in Nalimov Tablebases which are now used by many professional chess programs and services.
The total volume of all tablebases is 140 000 gigabytes, which is obviously too much for personal computers. Lomonosov Tablebases will be accessible online from the Aquarium interface and on the chessok.com website. All users of ChessOK Aquarium, Houdini Aquarium and Chess Assistant products get free access to the service for the period specified in their product description.
Early tablebases could only deal with settings of specific materials, e.g. K+Q vs K+R, but as computer performances improved, we saw the creation of general tablebases that could handle any combination of pieces up to a certain total number of units. A milestone was reached in 2012 when a Russian team used a supercomputer to generate the Lomonosov tablebases, which cover all possible endgames with seven units or fewer (barring the trivial cases of six pieces vs king). Consequently, the game of chess is more-or-less solved for such miniature positions! Here are some online resources for accessing these marvels of modern technology: (1) Nalimov EGTB - 6 pieces maximum (free); (2) Lomonosov Tablebases - 7 pieces maximum (annual subscription fee required, but free for fewer pieces); (3) Android app for Lomonosov - 7 pieces maximum (free and highly recommended). 2b1af7f3a8