Computer Chess Club Archives


Search

Terms

Messages

Subject: Re: About qsearch...

Author: Uri Blass

Date: 07:41:42 12/28/01

Go up one level in this thread


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



This page took 0.01 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.