Author: Robert Hyatt
Date: 09:13:03 11/04/00
Go up one level in this thread
On November 04, 2000 at 11:33:22, Ulrich Tuerke wrote: >>I'm not aware of anything that says that when using fail-soft, you _must_ start >>off at +/- infinity. > >Isn't it the definition of "fail soft", to initialize best = -infinity in the >full search region ? May be I'm confusing things again. > >> I don't, for example, yet I still let the search return >>values outside alpha/beta. > >I don't see how to get an upper bound < alpha, when the best value had been >initialized to alpha. Your search will just return the initial value in case of >a "fail low", won't it ? > >> I found it slightly better because you get a bit >>better info out of the hash table. But it was only a "bit" better. Not a huge >>win. > >Why do you get better info out of the hash table in this case ? > >> >>More important if you use mtd(f) of course. > >Thanks, Uli No... IE suppose you search at ply=10, and get a score of +.20... Then at the next iteration you start with a window (aspiration window) of something like -.10, +.50... with fail-soft you can get a score of +.90 or -.90 back. While that won't be an accurate score, it supposedly gives you a better idea of how far you need to relax the bound for the re-search... normally you do something like this: v=-Search(-beta,-alpha,depth-1,etc...) if (v >= beta) return (beta) the change is just to say if (v >- beta) return (v) and do that everywhere...
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.