Author: Uri Blass
Date: 23:17:37 11/27/03
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On November 28, 2003 at 01:49:57, Will Singleton wrote: >On November 28, 2003 at 01:43:39, Uri Blass wrote: > >>On November 28, 2003 at 01:21:16, Russell Reagan wrote: >> >>>I had this position in a game I played tonight. Analyzing it, I found that I >>>missed a draw. Ruffian took 9 seconds and 14 plies, while Crafty took 4 minutes >>>and 22 plies to see that it was a draw (Athlon 2GHz). Ruffian gives a draw score >>>after two repititions, so this might be why. I'm not sure what Crafty does. >>> >>>[D]8/8/8/1p6/8/8/pq3P2/3k2KQ w - - 0 76 >>> >>>While we're on the subject, what do you programmers think is the best approach >>>for repetition detection? Giving a draw score after two repetitions or waiting >>>until three? Or are there advantages to both approaches? >> >>There is no reason to wait for 3 repetition. >> >>3 repetitions means that the position repeats 4 times. >> >>it is certainly safe to give a draw score after 2 repetitions and for me even >>one repetition is enough to return a draw score. >> > >One repetition does not give a draw, by the rules of chess. Why would you >return a draw score when it is not a draw? > >Will There is a difference between repetition in the search and repetition of previous game position. I agree that repetition of previous game position should not be evaluated as a draw but I have other priority and fixing it is not my top priority. Repetition of position that never happened in the game means that in case of no draw there is a better line for the side who is better(if this side can win then it can win faster by not repeating) so by returning a draw score I simply prune illogical lines. Uri
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