Author: Ulrich Tuerke
Date: 04:29:30 05/25/02
Go up one level in this thread
On May 24, 2002 at 19:41:52, José Carlos wrote: >On May 24, 2002 at 18:14:57, J. Wesley Cleveland wrote: > >> I was looking at the source of crafty and saw that on a fail low, the value >>returned is alpha, rather than Max of all the values from the level below. Is >>there some disadvantage in returning the real upper bound? I think it causes >>some problems in Crafty making it much slower resolving fail-highs and fail-lows >>at the root as these branches all need to be re-searched. > > I use fail soft because I think (not tested) that it generates smaller trees >generally. > The drawback is that what you call "real upper bound" is no always so. Null >move and hashing make the search return "not totally correct bounds" some times. What do you mean by "not totally correct bound" ? I don't care for truth or correctness in my chess program; the aim is just to find a good move. In case my fail high verification search is failing low, I just stick to the alpha of the verification search and go on searching the remaining moves. I think, that's not really a problem. Regards, Uli >It is very common that you fail high in the root, research with a different >window and get a fail low. > So fail hard makes search more stable (it's less probable to get such >instabilities if you always return the search bounds). > > José C.
This page took 0 seconds to execute
Last modified: Thu, 15 Apr 21 08:11:13 -0700
Current Computer Chess Club Forums at Talkchess. This site by Sean Mintz.