Author: Bo Persson
Date: 12:12:10 09/03/02
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On September 03, 2002 at 12:03:24, Dave Gomboc wrote: >On September 03, 2002 at 11:49:42, Robert Hyatt wrote: > >>On September 03, 2002 at 11:30:35, Gian-Carlo Pascutto wrote: >> >> >>I worked on trying it for about three months. I didn't go "all the way" and >>add both upper/lower scores/moves into the hash table entries, as mtd(f) really >>needs. But I had to do so many re-searches that I didn't deem it worthwhile to >>worry with that... I did spend a lot of time trying to limit the number of >>re-searches. But if you do three or more, you begin to lose to straight PVS >>in the general case... >> >>and you are going to be forced to do at least two searches in the best case... > >Well, I do think you need to at least make that switch (to storing both upper >and lower bounds) to give it a fair shot. If you don't, the algorithm can >ping-pong like crazy with the "right" input :-) > >Dave Yes, you might want to try adding two bounds anyway. I started by modifying the hash table, and then accidentally forgot to include the MTD(f) code, but got a pretty good improvement anyway. Having two bounds helps reduing the alpha-beta windows from both sides. On the other hand, I have tried MTD(f) for a lot longer than 3 months, and still have this "fast, fast, fast, hit-the-wall" effect, where 10 plies takes less than a second and ply 11 takes forever. Bo Persson bop2@telia.com
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