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[Bug-gnubg] Race database and bearoff DB

From: Albert Silver
Subject: [Bug-gnubg] Race database and bearoff DB
Date: Mon, 30 Sep 2002 12:42:48 -0300

Well, as long as the discussion of the day is the bot’s development, I’ll take advantage and pass on the result of a long discussion I had with Kazaross at GG. We were discussing GNUbg in general, and he said he had an idea that he thought would significantly improve the bot’s play: race and bearoff databases.


He noted that in Snowie 2 and 3, there was a cubeless race DB that went up to the 10 point and that took up 294 MB. He said that in his opinion a DB that went up to the midpoint would improve the bot’s play enormously. I said that in chess, any increase in such databases increased the size of the files exponentially. For example, a complete 5-piece tablebase (every possible position with 5 pieces – including kings BTW) would take up about 7.5 GB. This has decreased since the idea was first incepted by Ken Thompson, and the 7.5 figure is for the Nalimov format. Chessmaster 9000 has a new algorithm that is even more efficient, but that’s another story. A 6-piece tablebase set would take up several terabytes. As it is, in Snowie 1, the race database went up to the 11 point, and the file was a mere 392 MB, so nothing cataclysmic involved. His suggestion makes sense, though I’m not sure about how this could be provided to users.


The single best source to download the chess tablebases is at the FTP of Dr. Robert Hyatt provided by his university, the University of AlabamaBirmingham. Otherwise, a user can download a tool and have their own machine build the tablebases. For 5 piece sets, this is possible though fairly long (a day or more depending on the PC). For any 6 piece set you have to download it though as a PC would take months for a single configuration.



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