Author: John Merlino
Date: 10:58:19 01/20/03
Go up one level in this thread
On January 20, 2003 at 13:11:48, Eiko Bleicher wrote: >Hi, > >AFAIK the endgame tablebases like the Nalimov Tablebases use one byte per >position. Thus, the max. length results in somewhere about 126 moves to win / >loose. > >Now the question is this: How do these databases handle the positions that are >mate in 130 or 140 or .... > >Any help would be greatly appreciated. > >Eiko First of all, it's an unsigned byte (8 bits), so it can handle mates up to 255 (or 254, if the 255 value is used for something else, about which I am not sure). I'm not exactly sure how Nalimov handles the 255 value. But, in Chessmaster 9000, which also uses an unsigned byte to store this value, all mates greater than or equal to 254 have the same value -- 254. Therefore, if more than one move has a value of "Mate in 254", then any one of these moves may be chosen as "best play". This may result in less than optimum play for two reasons: 1) One of these moves may be Mate in 254, and the other(s) may be Mate in much more than 254. This isn't necessarily a bad thing, except for... 2) One of these moves may be a mate that will not be subject to the 50-move rule, and the other(s) all will be draws with best play under the 50-move rule. jm
This page took 0 seconds to execute
Last modified: Thu, 15 Apr 21 08:11:13 -0700
Current Computer Chess Club Forums at Talkchess. This site by Sean Mintz.