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Subject: Re: Quiescent search question to programmers

Author: Ulrich Tuerke

Date: 18:36:00 03/09/03

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On March 09, 2003 at 18:13:31, Uri Blass wrote:

>On March 09, 2003 at 17:56:55, Ulrich Tuerke wrote:
>
>>On March 09, 2003 at 15:43:37, Russell Reagan wrote:
>>
>>>I think that most people subscribe to the school of thought that says that
>>>quiescent search is not perfect, so do it fast and "good enough" for most
>>>situations. If you could have a perfect quiescent search, what price would you
>>>be willing to pay? One ply of full width search? Two ply? Time to depth takes
>>>twice as long? I am interested what programmers with more experience than myself
>>>think about this.
>>
>>I think, that's an interesting field to experiment with. I have tested a lot of
>>ideas in quiescence search: pushes of passed pawns (if some pre-conditions
>>fulfilled), checking moves (if king to be checked is condidered to stand risky),
>>hanging pieces attempting to escape (only very close to the boundary of full
>>search).
>>OTOH, you're right; i think that this kind of q-search is expensive. Only
>>extensive testing can tell whether it's worthwhile. I do not know yet.
>>
>>Uli
>
>I am surprised that for you it is expensive,
>
>Comet is not one of the fast searchers so I thought that for you it should be
>not expensive.

I don't see your point. Why should a certain percentage of extra-nodes be
"cheaper" for a slower searcher than for a faster searcher ?

>
>I found it productive for test suites and I did not find a proof for big
>difference in games.
>
>I decided to keep it because I know that my function to generate checks in the
>first plies of the qsearch is not close to be optimal and I probably can get a
>significant improvement in speed by doing it faster in the future.

I do it different. So, we can't compare easily. In case the evaluation has
signaled that either king is "in danger", then I generate checking moves (to
that king) also deep in quies-search. OTOH, in a quiet position, I don't do them
at all.

These checks - together with escape of hanging pieces - slows down considerably.
I haven't really measured for a long time, but I guess this could account for
almost one iteration less in given time.

Uli

>
>Uri



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