Author: Stuart Cracraft
Date: 09:34:42 01/11/06
Go up one level in this thread
On January 10, 2006 at 21:44:30, Robert Hyatt wrote:
>On January 10, 2006 at 16:15:53, Stuart Cracraft wrote:
>
>>Hi - my extension credit is calculated for each ply in the search
>>and stored in several arrays, one for each type of extension.
>>
>>The arrays for the given current ply are summed together
>>
>> extension=0; // Prove that we must extend. We assume we don't at first.
>> :
>> :
>> AllExt[ply]=ChkExt[ply]+RecapExt[ply]+PawnExt[ply]+OneExt[ply]+ThreatExt[ply];
>> if (AllExt[ply]>=1.00) extension=1;
>> else if (ply>0 && AllExt[ply-1]<1.00 && AllExt[ply-1]+AllExt[ply]>=1.00) {
>> extension=1;
>> }
>> else if (ply>1 && AllExt[ply-1]<1.00 && AllExt[ply-2]<1.00
>> && AllExt[ply-2]+AllExt[ply-1]+AllExt[ply]>=1.00) {
>> extension=1;
>> }
>> if (BM_X != 0.0)
>> if (bmx) {
>> AllExt[ply]+=BM_X; extension++; bmext++;
>> }
>>
>>And if extension is "1" after all of this, then we extend by 1 the
>>current move at the current ply known as 'ply'.
>>
>>My questions are:
>>
>> I know that Bob Hyatt has used 0.75 as his check extension for many years
>> and indicates it is a critical factor in throttling runaway check extensions.
>
>Not quite. My "check" extension is 1.0. My "one-legal-reply" extension is .75,
>as is the recapture and mate threat extensions. But normal check is 1.0 until
>some ply limit is reached, at which point is is reduced to .5 to limit
>ridiculously deep searches.
>
>
>
>> My problem is that since I sum as above, setting the credit for CheckExt[ply]
>> (before the above code) to 0.75 would really be too little of a good thing,
>> nothing in fact, since I would only extend a check if there is an additional
>> consideration forcing a full extension and that is not what Bob meant.
>
>You are missing another point that is very significant. I am not doing
>extensions like you. I simply increment "depth" by the amount of the
>extensions, even if the total is something like .75. That won't cause a deeper
>search yet, but if a later ply adds just .25 more, then suddenly the search will
>go one ply deeper. It didn't appear that you are doing it that way. My
>fractional extensions are carried along, ply by ply, and slowly build up until
>they cause another ply of depth to be searched...
>
At which point you then reset the additive to zero so that it can start
accumulating again?
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