25

I'm not an expert on quantum computation but my understanding is that quantum computers are not expected to be useful for chess. Quantum algorithms are very good at finding needles in haystacks: the three big quantum algorithms are Shor's factorization algorithm, Grover's database lookup algorithm and the Deutsch–Jozsa algorithm, which essentially ...


21

Seven man end game table bases are already available online: http://chessok.com/?p=28049 By the end of 2013 they should be available off line as well. The size is 140 000 gigabytes so there is an obvious problem with copying them. They did not compute 6 white pieces versus 1 king since they decided it was pointless. Interesting fact- the longest forced ...


16

play the game until six pieces Stockfish doesn't do that, that's not what tablebase is for. Briefly, tablebase boosts engine search well before six-men position reached on the board. Let's do an exercise, add the board 5 pieces. Now you have 10 pieces on the board, and it's not something you can find in any tablebase. However, during the engine search ...


16

Since there is no single comprehensive publication this is based on the probing code, the generator and various explanations from Ronald de Man (the author of the generator). When probing pretty much any tablebase (aka huge compressed hash map): The position is normalized ... ... mapped to an integer index. The index is looked up in a table that identifies ...


16

There is a contradiction in terms in "only" generating practical endgame tablebases. We have to understand how tablebases are generated to see why. Tablebases are generated by working backwards from the final mating/drawing positions, "retracting" moves rather than playing them forward. First, every possible final position is exhaustively listed. Then from ...


14

Original Answer: 7-men Lomonosov is free as an Android application. Update - September 2018: 7-men Syzygy is available for free. Also available from Lichess.


14

Tablebases are databases of endgame positions, with few pieces left on the board (say a 5-man tablebase, which consists of all legal positions with 5 pieces on the board in total, including kings, say K+Q vs. K+R+B). These databases have the positions 'connected', i.e. they also contain the moves to get from one legal position to another (in particular, ...


12

As I do not have access to the full Lomosonov tablebases, here is an answer based on the Syzygy tablebases, which are available online in machine-readable format. I interpret your question as "how often does the side to move win, lose or draw". As the Syzygy tablebases only include positions where White has material advantage, we have to add the ...


10

Endgame tablebases are essentially databases containing known endgame positions that have been “solved”, so to speak. That is, every position in an endgame tablebase will have a corresponding result which will either be a win for white, a win for black, or a draw (assuming perfect play). They are used by chess engines because it is much more efficient for ...


10

The Lomonossov tablebases include all 7-man positions with the exception of 6 pieces vs lone king. Most material distributions you consider "ridiculous" are in fact required to evaluate "interesting" positions because of possible pawn promotions. This works recursively, so if you want to solve e.g. KPPPvKPP, you need (among others) the table KPPQvKPP first. ...


10

If the tablebase says that it's a draw with optimal play from both sides, then you can always ignore whatever Stockfish or any other engine says. The tablebase knows the objective evaluation for any position with 7 pieces or less. What Stockfish 11 (or any earlier version) does is calculate as far as it can ahead, evaluate the positions it reaches in its ...


9

Currently most of the 7-piece Lomonosov tablebases have been created. the only ones that weren't, were the K vs. K + 5 pieces. Those took about 6 months using the Lomonosov supercomputer. Based on this answer, creating the 8-piece tablebases could take 100x the time it took to create the 7-piece, give or take an order of magnitude. Extrapolating, that would ...


8

I am a developer currently working on software to compute endgame tablebases. The real bottleneck with calculating positions is not memory per se but the working memory and computing cycles needed to calculate a network for an exponentially-growing set of positions. The number of positions grows exponentially according to the number of men on the board; this ...


7

The fraction of all six-man positions that are unreachable from the starting position is very, very small. Removing them would have a tiny effect on the size of a six-man database. Here is an example of how rare these positions are. First of all, we can't get into one of these unreachable positions without a bishop and a pawn, so we already have a small ...


7

http://chessok.com/?page_id=27966 History Note 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. Experts didn’t expect 7-...


7

For a simple numerical example, take the endgame of King + Rook + Pawn vs. King + Rook. The number of possible positions is 64 x 63 x 62 x 61 x 60. Of those, 25% is not valid because the pawn is at the first or last row, and because of the symmetry around the d/e file, we only need to store the positions where the pawn is on the a, b, c or d file. This ...


7

Not only are we far from solving chess, in all likelihood chess will never be solved. There are more possible positions in chess than atoms in the known universe, so not only would in take forever (literally) to traverse the tree, but it would be impossible to store. At current cpu speeds, even with infinite storage, the universe would die of heat death ...


6

All of the Syzygy tablebases are available here: https://syzygy-tables.info/ These cover all endgames up to 7-man, and provide WDL (win-draw-loss) and DTZ (distance to zeroing move) data. Syzygy also distinguishes between a theoretical win or loss that can actually be forced into a draw by the 50-move rule, and one that cannot. Here's an example for ...


6

The best I could come up with is 7 moves, I don't believe it could take much longer, because with 4 queens there's not as much freedom as with 2, I cannot put black king in the middle of the board when capturing black queens while keeping king in check: 3q4/q7/q7/q7/8/8/8/k1K4Q w - - 0 1 And I made it nice as you asked -- the first move it not a capture! =)...


6

This max-DTZ position is mate in 8, but probably also a dead-end because it seems hard to improve starting here. [FEN "7q/4q1q1/8/8/3q2Q1/1K6/8/1k6 w - - 0 1"] 1. Qf5+ Qde4 2. Qf1+ Qe1 3. Qd3+ Ka1 4. Qa6+ Qa5 5. Qxa5+ Qa3+ 6. Qxa3+ Kb1 7. Qa2+ Kc1 8. Qc2#


6

The Lomonosov Endgame Tablebase supports 7 pieces. That means it has all the positions you describe in your question. Otherwise, it's not a tablebase by definition. The "ridiculous" positions you mention might not happen on the board but might still happen in the engine search. They're still important because pawns can promote, and a chess engine looks at ...


6

In various endgame tablebases, the terms mean as follows: Depth to Mate. For each position that is represented, 'DTM' indicates the theoretical value, and the number of winner's moves to 'Mate' if won/lost - assuming that the winner is minimizing and the loser is maximizing DTM. DTC Depth to Conversion 'Conversion' is the changing of the force on the ...


5

There exists a 7-men-endgames tablebase available online, the "Lomonosov endgame tablebase". see : http://chessok.com/?page_id=27966 Unfortunately, it is not free yet.


5

The 7 piece EGTB is not yet freely available online, as far as I know. Building the tablebase is costly in time and resources and the storage space is not cost-free either. Concerning http://tb7.chessok.com/ do not be too disappointed, because they mention this explicitly (at least today, maybe not on April 11th when you tried): "Currently the tablebases ...


5

This depends a great deal on how (and what) you count. In a discussion at the CCRL board, Kirill Kryukov offers the following counts on the number of unique legal positions (NULP) for some small numbers of pieces: Pieces NULP 2 462 3 368,079 4 125,246,598 5 25,912,594,054 6 3,787,154,440,416 ...


5

I don't know the exact answer for the 10x8 board (used e.g. in Capablanca Chess, where your Janus is called the Archbishop), but I have something that could get you well along toward an exact answer, though with some effort on your part (see further below). On the 8x8 board the max DTM is 17 moves (as you may already know). My conjecture is that the 10x8 ...


5

You are right that tablebases do not automatically contain information pertaining the fifty move rule. To use tablebases accurately currently engines use the DTZ50 metric (distance to zeroing with fifty move rule) which tells you the number of winning moves until the 50-move count is reset. If this number is too big, the position is evaluated as a draw. ...


4

https://syzygy-tables.info/ allows to look up 7-men endgame positions. It does not give DTM information for 6- and 7-men endgames, only DTZ50+. On one hand, it is compliant with 50-move rule, OTOH, DTZ50-optimal play can be ugly (if it is possible to push a pawn or sacrifice a piece, it will). Also available for download: https://tablebase.lichess.ovh/...


4

7-men Syzygy tables are available for download: ftp://ftp.chessdb.cn/pub/syzygy/ Mirrors: http://tablebase.sesse.net/syzygy/ https://tablebase.lichess.ovh/tables/standard/ As of August 2018, only latest development Stockfish (and some of its derivatives) supports them.


4

The 7-men databases from Lomonosov are available for free via their Android app. I've analyzed the traffic between the app and server a while ago, and discovered that it's easy to 'fake' your own calls to the server, so you're not depending on having an Android device nearby anymore. IIRC it worked with FEN strings. I don't have the specifics anymore, and ...


Only top voted, non community-wiki answers of a minimum length are eligible