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Subject: Re: EGTB' cell? Some additional questions

Author: Pham Minh Tri

Date: 15:27:49 03/04/01

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On March 03, 2001 at 23:08:39, Robert Hyatt wrote:

>On March 03, 2001 at 19:54:03, Pham Minh Tri wrote:
>
>>On March 03, 2001 at 10:29:40, Robert Hyatt wrote:
>>
>>>On March 03, 2001 at 02:44:01, Pham Minh Tri wrote:
>>>
>>>>Hi,
>>>>Could anyone explaint to me what content of a cell of EGTB is?
>>>>Thanks in advance,
>>>>Pham
>>>
>>>
>>>It is a single byte that either has a 0 (draw) or +/1 N, where N is the number
>>>of moves to the forced mate...
>>
>>Thank you very much for your answer. Could you tell me more:
>>- How to index a cell in EGTB?
>>- How large of EGTB of Crafty (how many entries)?
>>- How to orgnize raw data (the data would be converted into EGTB)?
>>
>>Thanks in advance,
>
>1.  the basic idea is that for a 4 piece ending, you take the square numbers
>for the 4 pieces, which are 6 bit numbers, and simply concatenate them into
>a "Godel number" that is 24 bits long.  This indexes to a single byte in
>the egtb.
>
>It is more complex than this because you don't need a 24 bit number, you can
>do it with a few less bits...
>
>all the 3-4-5 piece files for crafty take about 7.5 gigabytes of disk space.
>
>2.  You don't organize raw data... you do a search looking for all positions
>that are mate in 1, then mate in 2, etc...

- Do you mean the search done by other program (for building EGTB only) or by
chess program when searching a move?
- How useful is EGTB? I mean the frequence of use of EGTB and how speed slows
down.
- Is it possible to replace EGTB by improving evaluation function (not use
EGTB)?

Thanks,



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