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Statistical approach to chess?

Reading about how Google solves the translation problem got me thinking. Would it be possible to build a strong chess engine by analysing several million games and determining the best possible move based largely (completely?) on statistics? There are several such chess databases (this is one that has 4.5 million games), and one could potentially weight moves in identical (or mirrored or reflected) positions using factors such as the ratings of the players involved, how old the game is (to factor in improvements in chess theory) etc. Any reasons why this wouldn't be a feasible approach to building a chess engine?

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Chinmay Kanchi Avatar asked Apr 26 '10 22:04

Chinmay Kanchi


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2 Answers

Something like this is already done: it's the underlying concept of opening books.

Due to the nature of the game, computer AIs are notoriously bad in the beginning, when there are so many possibilities and the end goal is still far ahead. It starts to improve toward the middle, when tactical possibilities start to form, and can play perfectly in the end game far exceeding the capability of most humans.

To help the AI make good moves in the beginning, many engines rely on opening books instead: a statistically derived flowchart of moves, basically. Many games between highly rated players were analyzed, and recommendations are hard-coded into "the book", and while the positions are still in "the book", the AI doesn't even "think", and simply follow what "the book" says.

Some people can also memorize opening books (this is mostly why Fischer invented his random chess variant, so that memorization of openings becomes far less effective). Partly due to this, sometimes an unconventional move is made in the beginning, not because it's statistically the best move according to history, but precisely the opposite: it's not a "known" position, and can take your opponent (human or computer) "out of the book".

On the opposite end of the spectrum, there is something called endgame tablebase, which is basically a database of previously analyzed endgame positions. Since the positions were previously searched exhaustively, one can use this to enable perfect play: given any position, one can immediately decide if it's winning, losing, or draw, and what's the best way to achieve/avoid the outcome.

In chess, something like this is only feasible for the opening and endgame, though. The complexity of the middle game is what makes the game interesting. If one can play chess simply by looking up a table, then the game wouldn't be as exciting, interesting, and deep as it is.

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polygenelubricants Avatar answered Oct 14 '22 07:10

polygenelubricants


Well, 4.5 million games still only covers a very tiny (infinitesimal small) fraction of all possible games.

And while you would have a large number of winning and loosing positions, that would leave the problem of reducing that to a usable set of parameters. A very old problem, with neural networks as a standard approach. But NeuralNets aren't winning chess tournaments.

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Henk Holterman Avatar answered Oct 14 '22 07:10

Henk Holterman