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Subject: Re: busted position?

Author: James Swafford

Date: 06:44:10 02/23/06

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On February 23, 2006 at 09:41:52, James Swafford wrote:

>On February 23, 2006 at 09:10:47, Charles Roberson wrote:
>
>>
>>   Since I see others (Stuart) working on perft, I'll release a position that
>>  is helping me find a bug.
>>
>>     7k/8/8/8/1p6/8/PP6/6K w - - 0 0
>>
>>    Here are the results
>>      Depth    Hand Calculation    Telepath
>>         1            6                 6
>>         2           31                31
>>         3          319              1288
>>
>>     Either my hand calculations are wrong or Telepath has a bug in the
>>   EP code. The numbers represent the sum of all the nodes in the tree for that
>>   depth. Thus, the 6 root nodes are counted in the 2 ply and 3 ply counts.
>>
>>    Given that some do not count the nodes that way subtraction should do the
>>   trick with the depth counts being 6, 25 and 287 respectively.
>>
>>     I'd like to see somebody post perft results on this position for as many
>>    depths as possible assuming they think their engine produces correct
>>results.
>
>Here is what I get with Prophet:
>
>Initializing position...done.
>setboard 7k/8/8/8/1p6/8/PP6/6K w - - 0 0
>
>- - - - - - - k
>- - - - - - - -
>- - - - - - - -      white to move
>- - - - - - - -      no ep
>- p - - - - - -      no castling rights
>- - - - - - - -
>P P - - - - - -
>- - - - - - K R

Uhm, isn't this position busted?  How can white be on
move if the black king is in check?

--
James

>
>perft 2
>running perft on movegen: bitmap movegen
>
>29 moves (0 ms)
>perft 3
>running perft on movegen: bitmap movegen
>
>225 moves (0 ms)
>perft 4
>running perft on movegen: bitmap movegen
>
>1385 moves (1 ms)
>perft 5
>running perft on movegen: bitmap movegen
>
>11494 moves (6 ms)
>perft 6
>running perft on movegen: bitmap movegen
>
>77643 moves (56 ms)
>perft 7
>running perft on movegen: bitmap movegen
>
>655713 moves (330 ms)
>perft 8
>running perft on movegen: bitmap movegen
>
>639669 moves (331 ms)
>
>--
>James



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