Computer Chess Club Archives




Subject: Re: mate threat extension/null move

Author: Robert Hyatt

Date: 20:57:31 09/26/04

Go up one level in this thread

On September 26, 2004 at 08:25:04, Rick Bischoff wrote:

>It is probably blank after a certain ply because of your hash table-- e.g., you
>are getting a good draft for your depth with an exact hit... I suppose if it
>bothers you, you could just walk the hash table line like you do now and append
>Incidentally, I left my program running all night and I see that it solved it at
>ply 12 in 1324898 seconds which is not very good ;-(

You have one hell of a long night.  As in maybe 2 weeks of nighttime.  :)

>>For me -- 95 seconds is good.  Note the double variation is first the
>>regular pv[] triangular array if any and then the walk-the-pv method.
>>For some reason WAC 141 really kills my triangular array pv[] and I
>>do not know why. You see in most cases above it is blank.
>>My WAC problem was that after my quiescence went back into the main
>>search since quiescence node on entry was in check, I had not
>>completely disabled all main search extensions. I have disabled
>>all of those now and got the better result. The reason I did this
>>was David's comment about "all his extensions" and then another
>>comment about someone going to main search from quiescence incheck
>>situation with depth=0.
>>What was killing me was the additional recapture extensions after
>>an incheck extension *** at the same ply*** due to the above bug.
>>The bug had been there since nearly the beginning of the program
>>in June.
>>I know this is nothing compared to what others are solving
>>WAC 141 in but consider that my machine is probably 3x-5x slower
>>than your machines so I am really getting Qxf4 in 18-30 seconds
>>on that type of machine, so I am okay on WAC 141 now. I won't
>>be buying a newer faster computer until I can get a 64-bit box
>>that totally dusts this 1ghz P3. I.e. at least >=5x faster on
>>my program (I go to CostCo and test out the systems with my program.)
>>However, since I had to enable the recapture extension to do this,
>>my test result on WAC is about 8-9 positions fewer correct.
>>I did the above without a Botvinnik-Markoff extension and without
>>a Mate-Threat extension and with no checking moves in the quiescence
>>For the above I use only recapture extension and check evasion
>>moves in the main search and quiescence and one-reply extension in
>>main seach. I don't even hash the null position and do not store
>>any kind of threat information as mate-threat is not used.
>>I think most people solved the above problem with elaborate methods
>>of various extensions but I now don't see why that is necessary.
>>I have needlessly been suffering due to a) not turning off extensions
>>after handoff from incheck extension in quiescence over to main search
>>with new search depth of 1 and b) having a slower machine than others.
>>It was a bug in the *** existing code ***. Truly when Ernst Heinz said
>>that every computer chess program was a cornucopia of possible discovery,
>>he understated it signifcantly still. :-)

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