Author: Vincent Diepeveen
Date: 18:49:48 01/04/06
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On January 04, 2006 at 17:41:54, Charles Roberson wrote: > I've never seen this theory stated before, if anyone in any of the science >communities has then I want the reference. If anyone has similar experience or >sees a flaw in my logic, lets hear it. > > Is it possible for an improvement in search depth to result in a performance >degradation in match play. > > I am thinking yes! The implication is interesting. You improve the search of >your engine. That is the only change. It now searches two ply deeper. But in >match play it scores worse. Your natural thought was that all else was the same >thus you've a bug in your search improvement. Yes it is common for beginner engines that when they implement nullmove for first time, they play worse. All bugs in hashtable and qsearch and elsewhere backtrack sooner to the root then. However assuming a bugfree program and an improvement in search, that will always result in better play of course. Vincent > I think it is possible to improve the search and get worse results. Here is >how. > > Lets say that your position evaluator (PE) is out of tune on some >strategic/positional values. Deeper search works with the PE to create an edge >for your program. Your old search was keep pace (depth) with opponents, but the >new search sees two ply deeper on average. This gives your engine increased >opportunity to create an edge. Once the edge is realized, the engine is in a bad >position and the match is lost. > > Before it couldn't create the edge because it couldn't tactically out see >the opponents. Seems to me this scenario only happens when the PE is not >extremely out of tune, but is somewhat close to in tune. > > So, can increases in search depth in match play cause an out of tune PE to >reveal its issues. > > This seems to be happening in some my tests today. Other data my program >(prior) to the changes has a propensisty for getting into good opening and >middle game positions and then blowing it. Thus, increases in search depth may >allow it to see an advantageous postion (in its thoughts (PE)) and go for it at >earlier moves in the game. Also, increasing its chances of realizing those >positions. Thus, producing worse play.
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