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Subject: Re: busted position?

Author: Roman Hartmann

Date: 06:47:59 02/23/06

Go up one level in this thread


On February 23, 2006 at 09:44:10, James Swafford wrote:

>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

Where do you get that rook from? Seems the fen-string is broken and this
produces a ghost rook on your board.
Maybe he intended (like Thomas pointed already out) something like that
7k/8/8/8/1p6/8/PP6/7K w - - 0 0

Roman

>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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