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Subject: Re: Help: End Game and Hash Table Search

Author: Robert Hyatt

Date: 06:10:20 01/26/99

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On January 25, 1999 at 23:13:10, William Bryant wrote:

>On January 25, 1999 at 22:30:03, William Bryant wrote:
>
>>Shouldn't a mate-in-n score generate a cutoff and shorten the search
>>significantly.
>>
>>My new hash table seems to work well, however, in the end game (no table bases
>>yet), it finds mate-in-n but continues to search thousands and thousands of
>>nodes.
>>
>>Does a mate in n score need to be handled differently or is my hash code buggy.
>>
>
>
>Can this be handled inside the iterative deepening loop
>
>ie
>
>#define MateScore (9999 - MaxIterations)
>
>for (int depth = 0; depth < MaxIterations;depth++) {
>
>	x=search_Root(initialAlpha, initialBeta, depth);
>
>	if (x > MateScore) || (depth < -MateScore)
>		break;
>		//this is checkmate in the score backed up in the pv
>}
>
>or will this screw up bigtime somewhere.?
>
>Is there a better way to handle this?
>
>Thanks
>
>William
>wbryant@ix.netcom.com


I would ignore it... but you can handle it where you choose the 'next move'
to search.  ie at the top, if (value >= MATE-300) return(NO_MORE);

so you don't search more moves at any ply where you have found a mate.  You
have to do a little more than that to be sure you always 'make progress' but
that can work.  But really, who cares?



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