Author: Omid David Tabibi
Date: 10:42:06 11/23/02
Go up one level in this thread
On November 23, 2002 at 13:29:38, Martin Giepmans wrote: >On November 23, 2002 at 12:52:21, Omid David Tabibi wrote: > >>On November 23, 2002 at 11:37:25, Martin Giepmans wrote: >> >>>On November 23, 2002 at 08:48:36, Omid David Tabibi wrote: >>> >>>>On November 23, 2002 at 08:45:00, Uri Blass wrote: >>>> >>>>>On November 23, 2002 at 08:11:37, scott farrell wrote: >>>>> >>>>>>Just after other people's thoughts. >>>>>> >>>>>>I think Omid's work overlooked the adapative null move searching many of us do, >>>>>>ie. transitioning from r=3 to r=2. >>>>>> >>>>>>I think adaptive null move tries to GUESS where to use r=2 to reduce the errors >>>>>>that R=3 makes. I guess it depends on how often this GUESS is correct, the cost >>>>>>of the verification search, and how long it takes the adaptive searching to >>>>>>catch the error at the next ply. >>>>>> >>>>>>Has anyone looked at setting the verification search to reduced depth of 2 >>>>>>(rather than 1)? obviously to reduce the cost of the verification search. >>>>> >>>>>Omid checked it but you also reduce the gain. >>>>> >>>>>I think that I will look for good rules when to do the verification search so >>>>>the cost will be significantly smaller but the gain is going to be the same in >>>>>at least 99% of the cases. >>>>> >>>> >>>>I'm currently working on other variations. The initial results are promising. >>>> >>>>>Uri >>> >>>I have done some tests with your method at greater depths. >>>At depth 12 vrfd R=3 still had an overhead (in terms of treesize) of about >>>25% compared to pure R=3. >> >>Of course verified R=3 will *always* construct a larger tree than standard R=3. >>However, starting from a certain depth, it will always construct a smaller tree >>than standard R=2. >> >>Take note, that while verified R=3 constructs a slightly larger tree than >>standard R=3, it has a superior tactical strength to even R=2 ! >> >> >>> >>>(my engine uses a simple Q-search that shouldn't give problems here) >>> >>>So the question is if your expectation that the treesize of R=3 and vrfd R=3 >>>converge at greater depths (> 11) really holds. >>> >>>Needs more testing, I think. >>> >>>Another point: >>>I would expect that vrfd R=3 becomes less safe at greater depths. >>>The subtrees in which you don't verify nullmove (after the verification) become >>>deeper and I see no reason - on logical grounds - why this shouldn't give safety >>>problems. >>>Even if R=3 and vrfd R=3 converge in terms of treesize, the safety (or rather >>>the lack of it) might also converge ... >>> >> >>None will converge. > >That is what you hope. And hope is a good thing, for sure :) > That's what I hope? No, actually I would be happier if the tree size of vrfd R=3 and std R=3 would converge! But that is impossible, since verified R=3 has the verification overhead. >But how do you know? In your article there are no results for depths>11. > Look at Figure 4. The deeper you go, the larger becomes the difference between the tree size of vrfd R=3 and std R=2. >>However, the deeper you go, the smaller will be the difference in tree size, and the greater the difference in tactical strength. >> >Again, how do you know? > The "backbone" of verified null move pruning is R=3. So it is natural that the deeper you go, the size of the tree will be closer to standard R=3 than to standard R=2 (again see Figure 4). >Martin >> >>>In any case, thanks for sharing. >>> >>>Martin
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