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Subject: Re: Node count explosion

Author: Mridul Muralidharan

Date: 02:41:02 09/04/05

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On September 03, 2005 at 18:05:37, A. Cozzie wrote:

>On September 03, 2005 at 15:41:48, Mridul Muralidharan wrote:
>
>>[D]r2q3r/1b1k1pbp/p4np1/2BP1pN1/p1B5/P1Q5/1PP3PP/R3K2R w KQ - 0 19
>>
>>My engine royally blows up when it comes to this position (arrived at a game
>>against some engine a long while ago).
>>I suspected excessive extensions , qsearch problems , eval inconsistencies ,
>>bugs , etc.
>>Could not find any bugs and there were no obvious others problems ... the
>>position just kills the node count.
>>Analysed it with other engines and most if not all had similar problems.
>>
>>I have not done an actual position analysis of the position with a strong player
>>(that is tactics , positional aspects , etc - just analysed the stats that my
>>engine dumps for this pos).
>>
>>Any comments ?
>>
>>Thanks,
>>Mridul
>
>Hmm, Zappa too.  13 ply with its 'Columbus's peanut' settings (SE+history
>pruning) in 1 minute with *4* processors is pretty bad.
>
>anthony

Writing a new engine .... so I am dredging out old 'problem positions' and
analysing them !
I get 9 ply in a min on a 1.5Gig athlon box - sad :( ... no SE as of now but a
bit 'heavy' qsearch (modifications along the lines of what Ed described - though
what is in the code does not look anything like what he posted).
The % of checks which dont need to get extended is also pretty low in this
position about 25% or so for my program (usually , it is around 35 - 45) - I am
yet to add code to collect more stats - suspect some major instability 'cos of
the position.

"Columbus's peanut" - sounds 'nice' :-D
history pruning ? nothing else ? ;)

- Mridul



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