Author: Martin Giepmans
Date: 11:35:12 11/23/02
Go up one level in this thread
On November 23, 2002 at 13:42:06, Omid David Tabibi wrote: >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. > What I mean is that you apparently hope that at greater depths the tree for vrfd R=3 will only be slightly larger than the tree for pure R=3. > >>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). > Well, it is also "natural" that the deeper you go the risk of verified null move will be closer to standard R=3 than to standard R=2. No? That's my point. If at depth 14 (for instance) the overhead is still something like 25% while the gain in terms of safety is reduced to nearly nothing (which I expect) than ... what did you gain? You can only find out if you test at larger depths. In a few years we will reach depth 14 even in blitz games. So it is important. Martin > >>Martin >>> >>>>In any case, thanks for sharing. >>>> >>>>Martin
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