Computer Chess Club Archives




Subject: Re: mate threat extension/null move

Author: Rick Bischoff

Date: 05:25:04 09/26/04

Go up one level in this thread

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 ;-(

>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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