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Subject: Re: A test position for chess programs

Author: James T. Walker

Date: 14:19:26 12/10/00

Go up one level in this thread


On December 10, 2000 at 15:16:23, Uri Blass wrote:

>On December 10, 2000 at 13:16:06, James T. Walker wrote:
>
>>On December 10, 2000 at 11:47:15, Uri Blass wrote:
>>
>>>On December 10, 2000 at 11:35:10, Daniel Chancey wrote:
>>>
>>>>The personality, Chessmaster8000 (HB=16) found Rd5+ at 5:34 although the score
>>>>increased from 0.47 to 0.55 (favors white).  The move stayed through 10 minutes.
>>>>
>>>>Castle2000
>>>
>>>Black played Rd5+ so if the score increased from 0.47 to 0.55 then the score has
>>>to favour black.
>>>
>>>Uri
>>
>>Hello Uri,
>>In ChessMaster a + score is good for white so an increasing + score is even
>>better for white.  I gave the position to Rebel Century 3.0 on my Athlon 900 and
>>it finds Rd5+ after only 16 seconds but changes to Rb4 at 28 seconds.  Then it
>>switches back to Rd5+ after 1:06 and keeps it past 6:45 and 12 plies with a
>>score of 0.91.  I guess it will stick with it.
>>Jim
>
>Hello Jim,
>
>I do not have chessmaster8000 so I do not know the meaning of the scores of it
>and I used simple logic.
>
>Simple logic says that if Chessmaster changed its mind about the best move the
>score should be better for the side to move(black).
>Simple logic says that if the score was +0.47 for white then the score cannot be
>changed to 0.55 pawns for white when chessmaster suggest another move for black.
>
>I can explain behaviour like this only by hiding part of the information or
>lying about scores.
>
>Chessmaster needs to see a fail low for the move with evaluation of +0.47 for
>white.
>If chessmaster does not tell that the customer that it found a fail low for the
>move with evaluation +0.47 for white then it is hiding part of the information
>about the scores.
>
>
>Another possibility is that there are cases when chessmaster fails low without
>solving it and that the score of chessmaster is only a bound for the real score.
>
>I can understand if the score is changed from  at least 0.47 pawns for white to
>exactly 0.55 pawns for white(assuming that chessmaster decided not to solve the
>fail low problem) but in this case the score should be >=0.47 for white that
>should be translated to a number that is bigger than 0.55.
>
>If chessmaster says 0.47 for white and not >=0.47 pawns for white in this case
>then it is lying about the score.
>
>Uri


Hello Uri,
I think you are right.  I just posted an answer to another thread to William
about the scores of CM8K.  All of it's scores below 1.00 are positive.  I assume
this is a bug in the GUI and simplly printing the scores on the screen without
the "-" for scores below -1.00 when black is winning.  So in the above the
scores should have had a "-" in front to indicate black is better.  I hope this
will be fixed in the patch.
Jim



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