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Subject: Re: Nalimov TB question

Author: Bas Hamstra

Date: 03:59:51 11/12/01

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On November 12, 2001 at 04:46:19, Gian-Carlo Pascutto wrote:

>On November 11, 2001 at 19:42:29, Bas Hamstra wrote:
>
>>Is there any documentation about linking Nalimov?
>
>probe.txt, which comes with the generator
>
>>I am not sure what score a probe() should return. I set up a FINE that is a mate
>>in 23 (verified on nalimov's online TB site). However, when my probing function
>>returns 32756. Some debugging in TBIndex.cpp learns that initially it found 113
>>that is then converted to 32756 by macro S_to_L. Doesn't seem right. Shouldn't
>>it just return the number of moves to mate eventually? Peeking in Crafty seems
>>to indicate so.
>
>I figured out the conversion formula by setting up some positions
>and looking at the values I got back until I figured it out.
>
>In Sjeng, it looks like this:
>
>if (tbScore == bev_broken) return KINGCAP;
>
>  EGTBHits++;
>
>  if (tbScore > 0)
>  {
>        return ((tbScore-bev_mi1)*2+INF-ply-1);
>  }
>  else if (tbScore < 0)
>  {
>        return ((tbScore+bev_mi1)*2-INF+ply);
>  }
>  return 0;

Hi GianCarlo,

I saw this in Crafty too. But that doesn't give me a realistic value at all.
However if I use L_bev_mi1 (like in ExChess) in stead it comes more in the right
direction. But that gives me a M13 in stead of the M23.

(I checked in TBIndex.cpp the right squares are found)



Best regards,
Bas.



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