Author: Ricardo Gibert
Date: 17:42:45 07/10/02
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On July 10, 2002 at 11:04:34, Sune Fischer wrote: >On July 10, 2002 at 09:30:30, Ricardo Gibert wrote: > >>On July 10, 2002 at 04:30:28, Sune Fischer wrote: >> >>>On July 10, 2002 at 01:02:38, Ricardo Gibert wrote: >>> >>>>I find it fascinating that so many very experienced computer chess programmers >>>>do not understand some rather fundamental properties of alpha-beta search. >>>> >>>>What RH ran into was actually quite predictable. As MF put it, "I'm surprised >>>>that you're surprised." >>> >>>In a PV search some of the nodes are searched twice, so if you get something >>>outside the zero window because of a collision, it slows you down as you have to >>>research, but it doesn't hurt you unless you get another collision while >>>researching. >>> >>>-S. >> >>This is not a property of using PVS. A normal alpha-beta search plus hash table >>does this too. > >How so? >I would say it does the opposite, since its about refuting moves. What either one of us has to say on this is really irrelevant. RH needs to conduct a more reasonable test. The manner in which he generated the collisions plus the use of PVS should be changed. > >But thinking further about it, the collision could also return a false score >outside alpha-beta, so the move is refuted when it should not be. I don't know >which is worse, but at least landing _inside_ is harmless as we just research, >which was my point. > >-S.
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