Author: martin fierz
Date: 01:56:45 11/28/03
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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 i don't know why your crafty needs this long. my stupid engine sees the draw score after 1 minute on P4 2.4GHz at depth 15. which just goes to show how stupid it is compared to ruffian - needs a ply more and much more time. i'm not doing any clever stuff to catch repetitions (i do have a 1-ply check extension which might help detecting a perpetual though?), so i'm surprised that crafty needs a deeper search than my thing to find this - but perhaps it's also a problem with your crafty setup as bob suggested? >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? i return a draw score on the first repetition. if it's the first repetition of a position that occurred in the search, that is correct. if you include repetitions of game history positions, it's not correct, but not completely incorrect either - as a human you also might want to speculate that the opponent repeats moves when you're in an inferior position. cheers martin
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