Author: Robert Hyatt
Date: 19:04:44 07/10/02
Go up one level in this thread
On July 10, 2002 at 20:42:45, Ricardo Gibert wrote: >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. How would you suggest generating the collisions? As far as dropping PVS however, I disagree on. That is what I _use_ in real games. That is what I want to understand the behavior of. I don't care about variants of alpha/beta that I am not using myself (ie mtd(f) or something else that is non-PVS). > >> >>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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