Author: Robert Hyatt
Date: 20:30:52 08/27/05
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On August 27, 2005 at 15:36:15, rasjid chan wrote: >On August 27, 2005 at 10:09:21, Jon Dart wrote: > >>> So this mean we don't need to keep pv[][] if we have hash tables (it is >>> like double accounting). >> >>I think this is false, given you have a finite size hash table and must >>eventually replace something. I have some experience: I used to retrieve pv from >>the hash table but now use a pv array and back up the scores. >> >>--Jon > >They tell me so and I begin to doubt. Maybe as Dr Hyatt says, backup the pv. >It may be best to be simple as I don't yet know how hashing twists and turns >within. > >Rasjid Just remember this. While searching the PV, _after_ you search a move on the PV path, you do a lot of other searching. Any of which can overwrite the PV move so that you get no move at that point, and a resulting short PV. The "back up" method has no significant cost associated with it, since it is not done very often in a PVS-type search... If you really don't care, the hash table approach works much of the time, and does have zero overhead. The array backup method has a finite but small overhead. I find that avoiding the short PVs helps in testing and debugging, but in real games is irrelevant with respect to the game outcome...
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