Author: Ratko V Tomic
Date: 17:59:30 10/21/01
Go up one level in this thread
Dan: >>I don't know why you need to know the distance to mate (which is given >> as the reason not to store the move). If you make the best >> possible move, then it does not matter what the distance is. >If you only use N piece tablebases once you are down to N pieces on >the board, then your idea would work. However you also need to be >able to probe them when you reach an N piece position in the search, >and want to find out if this position is won or lost. For this purpose >all you need is win/draw/loss, and some people do use tablebases that >only store this information since they take less space. But to find >the shortest win when searching a position with more than N pieces, >you need to have distance to mate stored in the table. Dan was talking about keeping the best move (instead of distance to mate), not the win/draw/loss only. Knowing the best move implies the knowledge of the distance to mate since the child nodes of a table position are also table positions i.e. one can follow the best moves and obtain quickly the distance to mate. So, here one would trade off potentially large quantities of table space for some additional time cost in extracting the distance-to-mate value from the best-move value. Since the best-move encoding can take advantage of any endgame knowledge one can put into the move generator (used to list the available moves and specify the best one), this approach allows potentially large space savings which is further improvable as the more knowledge gets added to the encoder (using arithmetic encoding and a good quality generator, one may encode the best move in a fraction of a single bit, at least for those clasess of endgame positions where the generator can offer the best move with a probability greater than 50%). The direct distance to mate encoding doesn't offer any obvious way to save space by adding endgame knowledge into the encoder.
This page took 0.01 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.