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Subject: Re: To check or not to check, this is the quiescence question

Author: Robert Hyatt

Date: 08:55:01 10/14/03

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On October 14, 2003 at 11:01:09, Uri Blass wrote:

>On October 14, 2003 at 10:55:51, Robert Hyatt wrote:
>
>>On October 14, 2003 at 10:31:49, Tord Romstad wrote:
>>
>>>On October 14, 2003 at 10:06:41, Robert Hyatt wrote:
>>>
>>>>On October 14, 2003 at 08:42:05, Tord Romstad wrote:
>>>
>>>>>I think it is a good idea to use the SEE for checking moves, too.  Only search
>>>>>checks which do not lose material.
>>>>
>>>>Then you admit defeat before you start.  See the simple draw by stalemate
>>>>idea where you have a king and rook, and your king can't move.  You just
>>>>make unsafe check after unsafe check because the rook can't be taken.
>>>
>>>I don't see how not searching losing checks in the qsearch is admitting defeat
>>>any more than not searching losing captures is.  In both cases, you will make
>>>mistakes, but also save lots of time.
>>
>>That's the point.  "admitting defeat" means "accepting additional errors".
>>
>>I wasn't talking about losing games, specifically.  The q-search based only
>>on captures if _full_ of errors.  It fails to understand any tactic except
>>those specifically depending on captures.  IE no pins.  No threats.  No
>>double attacks.  No skewers.  No checks.
>>
>>If you add safe checks, that is a small part of the above list of things it
>>will overlook.  A part small enough that it probably won't help much, and
>>it might hurt if it wastes too much time.
>>
>>Perhaps my "admitting defeat" was too vague a descriptive term??
>>
>>
>>>
>>>>Safe checks are probably better than no checks, assuming you believe you
>>>>have to do checks in the q-search.  But, as I have said so many times, if
>>>>your q-search is going to have so many holes, find a way to avoid putting
>>>>such a heavy responsibility on the q-search in the first place.
>>>
>>>Sure.  I wish I could get good results with a minimalistic qsearch like
>>>yours.  Unfortunately it never worked very well so far.  But perhaps
>>>Omid is right that a minimalistic qsearch works better with nullmove
>>>R=2 than with R=3 (which I use).  I will run some experiments with R=2
>>>and no checks in qsearch when I find the time.
>>>
>>>Tord
>>
>>I use R=3 to R=2, and I really haven't seen anything bad.
>
>bad is something relative.
>
>My guess is that Crafty can be better with the right implementation of checks
>in the qsearch.
>
>Uri

My guess is that the "right implementation of checks in the q-search" is
going to be _extremely_ difficult to find.  Meanwhile, time spent elsewhere
will show bigger gains.




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