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Subject: Re: Re KRPKBP

Author: Laurens Winkelhagen

Date: 06:16:58 11/22/04

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On November 22, 2004 at 07:53:27, Steve Coladonato wrote:

>On November 22, 2004 at 05:49:05, Laurens Winkelhagen wrote:
>
>>On November 21, 2004 at 19:49:42, Steve Coladonato wrote:
>>
>>>On November 19, 2004 at 15:45:51, GuyHaworth wrote:
>>>
>>>>
>>>>Confirmed:  Marc has done KRPKBP and Eugene has done 19+ 3-3p EGTs but not this
>>>>one.
>>>>
>>>>1-0 maxDTM = 166 wtm and 153 btm:  0-1 maxDTM = 103 wtm and 104 btm.
>>>>
>>>>g
>>>Guy,
>>>
>>>I'm not familiar with tablebases and I don't understand your score.  I am
>>>reading it this way: maxDTM = Max depth to mate
>>>             wtm = white to move
>>>             btm = black to move
>>>What I don't understand is the 1-0 and 0-1 score.  Could you explain it for me?
>>>
>>>Thanks.
>>>
>>>Steve
>>My guess:
>>
>>Because there is a difference between the white and black side, it makes a
>>difference which side mates. The above score tells us that the biggest maxDTM is
>>when the white (KRP) is to move and to win.
>>    wtw btw
>>wtm 166 103
>>btm 153 104
>>
>>It seems logical that if black (KBP) is to win, then the mate should be shorter,
>>because one may not give white a chance to take the pawn with the rook.
>>Obviously this is easier when the pawn is closer to promotion.
>>
>>One puzzling thing left is that it makes a big difference for white to mate if
>>black is to move or white is. One would expect only a difference of 1, not of
>>13. It probably has something to do with going over into a different tablebase?
>>
>>Regards, Laurens
>
>Laurens,
>
>I thought the purpose of the tablebases was to provide "best" move evaluation of
>a position.  In which case, only one side [either white or black but not either]
>would win or it is a draw.  I suppose the starting position could enter into
>which side will win and perhaps that is why the above shows statistics for
>either side winning.
>
>Steve

Hi Steve,

I'm not sure if I understand you correctly, so I don't know if this reply will
make sense to you, but:
tablebases only tell only one side of the story: there is a KRPKBP tablebase but
there won't be a KBPKRP tablebase. The board is flipped appropriately. There are
obviously positions where KBP will win over KRP, which is why there are both
maxDTM for 1-0 and for 0-1. There wouln't need to be 0-1 maxDTM scores when
there would be a seperate KBPKRP tablebase, but there isn't;-)

Hope I make sense, Laurens.



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