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Subject: Re: q-search question

Author: Landon Rabern

Date: 11:51:17 07/19/00

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On July 19, 2000 at 14:08:23, Andrew Dados wrote:

>On July 19, 2000 at 14:00:16, Landon Rabern wrote:
>
>>On July 19, 2000 at 13:22:47, Andrew Dados wrote:
>>
>>>On July 19, 2000 at 12:03:10, Landon Rabern wrote:
>>>
>>>>I have been discarding all captures where attackervalue>DefenderValue in my
>>>>q-search which speeds it up significantly, but I know that it is throwing away
>>>>some captures that are good.  So I implemented a SEE function.  The SEE returns
>>>>the correct value on tests I have run.  When I put this into my program so that
>>>>if (attackervalue>DefenderValue)&&(SEE>=0) I keep the move as well, I got worse
>>>>results on the WAC test suite.  Before I put the see in I got 270/300 at 60
>>>>seconds per move and after I got 257/300 at 60 seconds per move.
>>>>
>>>>Is it just that there are no capture sequences in this test that need the extra
>>>>captures, or is there something wrong with my SEE function?
>>>>
>>>>Thanks for any help,
>>>>
>>>>
>>>>Landon W. Rabern
>>>
>>>It would be of help if you post some relevant positions. I may just guess now
>>>that if you do check detection in qsearch you may find some mating combinations
>>>with 'losing captures', when recapturing piece is overloaded simply, so in next
>>>move capture is mate. (Or you may do some non-capturing,checking moves in
>>>qsearch which complicates matters still). With SEE you miss those. Question is
>>>if average speedup of SEE in non-tactical positions offsets those few missed by
>>>using SEE....
>>>
>>>-Andrew-
>>
>>I do not do checks in q-search.  The problem is that I should be missing fewer
>>tactical positions with SEE, than with just throwing all captures out where
>>attackerValue>defenderValue.
>>
>>Landon
>
>So maybe you are much faster then SEE with throwing away all captures where
>attackerValue>defenderValue... Single out those positions and compare PVs and
>nodes produced with both versions of your qsearch ply by ply. Then maybe you/we
>can learn what's going on. Do you reach extra ply or does your program find
>those moves one/few plys sooner?
>
>-Andrew-

I rememeber reaching an extra ply in many cases, I can not take a look at the
PV's until late tonight since I am at work now and will be working late to get
the product out on time.

Landon



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