Author: Heiner Marxen
Date: 12:22:39 11/12/01
Go up one level in this thread
On November 12, 2001 at 08:14:32, Gian-Carlo Pascutto wrote:
>On November 12, 2001 at 06:59:51, Bas Hamstra wrote:
>
>>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)
>>
>
>M23 = ((M13-1)*2)-1
>
>If you compare this to the formula above you will see it is similar.
>
>I'm sorry I cannot be of more help, but I think the best thing
>to do is not to try to figure out how other formulas work (depends
>too much on how you represent mate scores in your program), but
>to set up a few positions where you know what the score should be,
>and look at what the probing function gives you back.
>
>By comparing the two, it should not be hard to arrive at the correct
>formula for your program. At least, thats how I did it :)
>
>--
>GCP
Here is the relevant part from Chest:
v = L_TbtProbeTable(iTb, side, ind);
XDB(1, printf("= eg_probe v=%d\n", (int)v); )
/*
* Now, we must translate back that value into a value,
* which we understand...
*/
if( v == L_bev_broken ) {
scinc(egsc.prob_broken);
q = EGQ_DUNNO;
}else if( v == L_bev_draw ) {
scinc(egsc.prob_draw);
q = EGQ_DRAW;
}else if( v > 0 ) { /* wins */
/*
* Deeper wins have smaller values.
*/
scinc(egsc.prob_wins);
q = EGQ_WINS_Q(1 + (L_bev_mi1 - v));
}else { /* lost */
/*
* Deeper losses have larger values (less negative).
*/
scinc(egsc.prob_loss);
q = EGQ_LOST_Q(v - L_bev_li0);
}
XDB(1, printf("< eg_probe q=%d\n", (int)q); )
return q;
EGQ_WINS_Q(N) codes "mate in N"
EGQ_LOST_Q(N) codes "is followed by mate in N"
L_bev_mi1 == "mate in 1"
L_bev_li0 == "lost in 0"
That should be a usable starting point.
Heiner
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