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[Bug-gnubg] Re: Race database and bearoff DB

From: pepe
Subject: [Bug-gnubg] Re: Race database and bearoff DB
Date: Tue, 01 Oct 2002 05:00:29 +1200

Again, this is not entirely new. The suggestion to enhance the race DB is based on the assumption that the bot misplays those positions. I would like to see the evidence for that. I think I will start an effort to measure the race net error just to make sure (similar to the crashed net). Also, I find it hard to belive the bearoff database is insuffcient. Can you pose this Q to Neil? i.e. can he provide a set of positions GNU mishandles? -Joseph Albert Silver writes:
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 Alabama -
Birmingham. 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

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