Author: Uri Blass
Date: 07:41:42 12/28/01
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On December 28, 2001 at 09:45:15, Severi Salminen wrote: >>if you extend the qsearch too much you may get >>often irrelevant positions that you analyze. >> >>The problem is that one of the players could win the game >>by a move that is not included in the qsearch. >> >>The probability for it increases when >>the number of plies increase and it seems clear >>to me that if you search deep enough the score that >>you have is often not relevant because you can be almost sure >>that the score in the qsearch for one of the previous nodes >>is wrong so you earn less information >>from searching more nodes and at some point common sense >>says that you need to stop because you pay more than you get. > >The problem is that you cannot safely terminate qsearch at some arbitary depth. >There is no way to know when the qsearch info is complete or when it isn't. >Qsearch is approximation and that's the way it's supposed to be. Limiting it >will only create problems as you will _allways_ get a really bad score when >limiting it during a capture sequence. And this will give totally wrong results >as opposed to non-limited qsearch. But as soon as I get home I'll test it and >report maybe some results. It is of course true that qsearch doesn't give >totally accurate scores but it really shouldn't as it is selective in its >nature. It's only function is to dynamically resolve the capture sequences in >frontier nodes. It would be equally illogical to limit the number of attackers >in a SEE function. The results would be also very wrong. Think qsearch as >dynamic SEE, well, that's what I do. > >Severi I think that I will not continue to argue about this point but it does not mean that I agree. I know that selective search is something that I cannot be sure about but there is a difference if there is a result that I can be sure in 90% that it is correct tatctically and if there is a result that I can be sure only in 40%. It may be interesting to look at many qsearches of more than 7 plies in order to find out how many of them have a tactical mistake that means that there is a better move at some ply that is not considered in the qsearch. Uri
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