Author: Don Dailey
Date: 07:50:01 06/22/98
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On June 22, 1998 at 09:51:27, Robert Hyatt wrote: >On June 22, 1998 at 02:37:40, Roland Pfister wrote: > >>I was on saturday at the townhall to watch Anand - Fritz and perhaps >>meet some computer chess freaks. >> >>But the only persons I knew were the two Matthiasses from ChessBase >>and Frederic Friedel. Frederic was busy photgraphing or videoing, so >>I had a small talk with Matthias W. and he told me that Fritz played the >>open too, at that moment having 5 points out of 5. Not bad. >> >>Then Mathias F. arrived, he was the one to operate Fritz. I asked him >>how they did parallize Fritz and he answered "MTDF", because they >>did not have the time to do something clever like Bob. > >this sounds like they did something very ugly, like searching a different >mtd(f) on each processor? But in any case, if they used mtd(f), then we >didn't see the "real fritz" play chess here, because mtd(f) is also not >quick and dirty to implement. It requires lots of algorithm changes, it >*definitely* requires significant hash-table changes, and so forth. Seems >like they were too interested in going faster, but overlooked difficulties >in getting stronger. I think mtd(f) is a pretty logical choice for a parallel machine if you were in a big hurry. I think the key thing that they must have considered was how clean and simple the algorithm is and the zero width window searches which is ideal for parallel chess. Yes, there are side affects that eventually create lots of implementation work later but these are not so serious that cannot be ignored (if you are in a big hurry.) I'm guessing that they are not doing what you conjectured, but are simply spawning off sibling searches in parallel with of course mtd's zero width window. I wonder if they have abort in the code or simply wait? I can imagine these considerations might very well push you to consider mtd(f) in a parallel program. Another possibility for easy implementation is mtd(f) with young brothers wait, then spawn off siblings in parallel with no aborting. Not having to worry about re-searching must also be a desirable characteristic for a quick and dirty implementation and another reason they might have considered mtd(f). - Don
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