Author: Omid David
Date: 18:26:30 07/13/02
Go up one level in this thread
On July 13, 2002 at 11:52:36, Vincent Diepeveen wrote: >On July 13, 2002 at 11:09:19, Omid David wrote: > >>On July 13, 2002 at 10:33:19, Vincent Diepeveen wrote: >> >>>On July 13, 2002 at 04:47:16, Omid David wrote: >>> >>>>On July 13, 2002 at 02:39:38, Dann Corbit wrote: >>>> >>>>>On July 13, 2002 at 02:22:00, Omid David wrote: >>>>> >>>>>>On July 13, 2002 at 02:07:17, Vincent Diepeveen wrote: >>>>>> >>>>>>>I still do not understand which positions you talk about which R=2 >>>>>>>is finding and R=3 isn't. >>>>>> >>>>>>I read your other post, that's also my point: Although at fixed depth, R=2 is >>>>>>much better than R=3 (see also "adaptive null-move pruning" Heinz 1999), in >>>>>>practice R=3 performs about the same as R=2 since on many occasions it finds the >>>>>>correct move one ply later with lower search cost. >>>>> >>>>>By the way, if you have not found Vincent's post on double null move you should >>>>>look it up. It is a clear win for sure. >>>> >>>>Yes it's a nice idea. But the main null-move pruning deficiency is its tactical >>>>weakness due to horizon effect. Zugzwangs are not a major problem, and as >>>>Vincent points out, he invented the double null-move idea just to show that >>>>null-move pruning is OK. Now nobody doubts effectiveness of null-move pruning at >>>>all, the only discussion nowadays is the depth reduction value. >>> >>>I'm missing any position where you have a problem though. Seems to me >>>your thing is incredible weak, and or doing other dubious things which >>>gets looked up in hashtable, after which it weakens your program. >>> >>>In DIEP i don't have all these problems. >>> - no dubious forward pruning >>> - no futility >>> - no razoring or any of these techniques. >>> - checks in qsearch >>> >>>Just PVS with nullmove R=3 and a bunch of extensions. That's it. >>> >>>Means that after a nullmove i don't get transpositions to positions >>>where you have stored a score which is based upon a dubious score. >>> >>>Best regards, >>>Vincent >> >>Why do you think there is a problem?! All the results I got are natural. I'm >>sure even in DIEP, R=2 works better under "fixed theoretical" conditions. > >No it works worse, because i search at least a ply less deeply. If i search >a ply deeper that doesn't only mean i get a ply more. Because the depth >is already pretty decent it also means all extensions might get triggered >a ply extra (like singular extensions). > >>However in practice you don't search to fixed depth and thus R=3 might be better >>in practice. >> >>My only point is that "R=3 might be better than most people consider it." (Take >>DIEP as a successful use of R=3) >> >>P.S. >>Have you published anything regarding double null-move? > >I simply posted in CCC and RGCC. the thing is real easy. >allow 2 nullmoves in a row always, but not 3. >Exception is if both sides only have pawns (of course you >can solve a few testset positions sooner by saying that >if either side has only pawns you don't allow nullmove >FOR BOTH SIDES, but that's in reality not so smart to do). > >Apart from that the normal conditions that i don't nullmove >when in check. > >This in fact results in nullmove not missing zugzwangs anymore. >Of course for more than 1 zugzwang the extra depth needed is >pretty big. > >Best regards, >Vincent I'd rather see such articles as "double null-move pruning" in ICCA than the usual pure-theoretical-non-practical articles!
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