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 configuration.
Albert