Author: Uri Blass
Date: 01:36:26 08/17/03
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On August 17, 2003 at 04:27:06, Rudolf Huber wrote: >On August 16, 2003 at 17:17:26, Tord Romstad wrote: > >>The last few weeks I have been experimenting with MTD(f). It still does not >>work quite as well >>as my old aspiration alpha beta search, but I intend to keep working on it for >>some more time. >> >... >> >>Another problem is that MTD(f) has very weird effects when combined with the >>various forward >>pruning techniques I use. This is not entirely unexpected, because I use the >>values of alpha >>and beta for pruning decisions. When I replace plain MTD(f) (which I haven't >>been able to >>make work very well; too many researches) with MTD(f) with a convergence >>accelerator, I >>often get entirely different search results for the same position. If I remove >>all selectivity >>(except null move pruning) from my search, changing the test driver does not >>have any >>effect on the search results, but then my program becomes much too slow. I >>suppose I >>will have to work out new forward pruning techniques. >> >>Tord > >First scan you source files for occurences of alpha and beta. If you >find any look hard and try to understand what you are doing there. In >mtd(f) there ist NO alpha and NO real beta. All the things (lazy eval?) >you do with alpha and beta are most likely wrong. Use the last score instead. > >Also I think it is a good idea to keep it simple. Why not disabling >forward pruning and your "convergence accelerator" and first try to make >your mtd(f) implementation better than negascout. > > >Rudolf The target is not to do something better than negascout but something better than the previous program. I see no reason to use mtd(f) if it does not help to be better than the previous version. Uri
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