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Subject: Re: Bitbases - yace, scorpio, gambitfruit

Author: Daniel Shawul

Date: 21:21:19 12/06/05

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On December 06, 2005 at 13:16:24, Zappa wrote:

>On December 06, 2005 at 05:07:25, Daniel Shawul wrote:
>
>>On December 06, 2005 at 04:58:01, Ryan B. wrote:
>>
>>>On December 06, 2005 at 04:41:25, Bernhard Bauer wrote:
>>>
>>>>Hi,
>>>>the use of bitbases looks promising. Gambitfruit makes use of Scorpio bitbases.
>>>>Dieter Buersner uses bitbases in yace too.
>>>>Dieter has more files and they are smaller than the scorpio bitbases.
>>>>Would it be possible for the author of gambitfruit to use the bitbases from
>>>>yace? Is there kind of a standard in bitbases?
>>>>Kind regards
>>>>Bernhard
>>>
>>>I think Danial plans on doing 5 piece bitbases and when they are ready I plan on
>>>supporting them in Gambit Fruit.  I hope people notice what Danial has done with
>>>making his bitbases easy to use and other engines start picking them up.  The
>>>way I see it maybe some idea I use in Gambit Fruit will be seen by another
>>>programmer and help them in some way but likely if a program is not already
>>>using bitbases it can benefit from the use of Danial's easy to use bitbases.
>>>
>>>Ryan
>>  Thanks for the support. I would have used some body else's bitbases myself
>>if i find a free one. Johan Melin (Knight Dreamer) has a similar DLL which can
>>be used by others. But it is not completely free though.
>>
>>For Bernhard:
>> AFAIK yace bitbases are not public. And scorpio bitbases are not larger than
>>yace's. Scorpio takes 18mb, yace takes 21mb, but that is insignificant.
>>For example the compressed bitbases that i have now for 4 pieces are 6mb large.
>>But that hurts speed of the engine. Knight Dreamers bitbases are 1mb in size
>>
>>Engines that i know have bitbases:
>>    KnightDreamer,Yace,Kiwi,Delfi,SlowChess,glaurung,GLC
>>
>>best
>>daniel
>
>How does KD manage to get so much smaller?
>
>anthony

KD uses binary dicision trees to store the data. Also for some of the
bitbases it only stores the execptions. Delfi's are even smaller.
There is also a recent paper on compression using ordinary binary decision
diagrams OBDDs, according to the author 4 piece bitbases  take only 1mb.
And the decompression speed is very small (as fast as normal evaluation of a
positon).
daniel



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