Author: Peter Kappler
Date: 21:51:01 05/23/00
Go up one level in this thread
On May 24, 2000 at 00:17:35, Robert Hyatt wrote: >On May 23, 2000 at 22:54:45, Peter Kappler wrote: > >>On May 23, 2000 at 21:30:26, Dann Corbit wrote: >> >>>On May 23, 2000 at 18:24:21, Mark Young wrote: >>>[snip] >>>>Lets be generous and say a ply is worth 100 rating points, and we can take Fritz >>>>6a for an example. Now you said it does not matter if it?s the 1st going to 2 or >>>>14 ply going to 15 ply. Its pretty much the same, if I understand you >>>>correctly. Lets assume Fritz 6a plays at a 2500 rating +/- 100 rating points, >>>>with a average middle games search depth of 15 plies. >>>> >>>>15ply X 100 rating points = 1500 rating. Where are the extra 1000 rating points >>>>coming from? Is Fritz really rated 1500, or are some plies worth much more the >>>>others. >>>> >>>>It is clear that the early plies are worth much more the later plies, and if you >>>>plot it out it?s a curve. I don't know of one program that does not exhibit a >>>>curve. >>> >>>That is well established, as both Dr. Hyatt's and Dr. Heinz's experiments >>>showed. However, as the depths increased, two very surprising things surfaced. >>> >>>At extreme depths, a linear model fits just as well as an exponential one. >>>Hence, there may (or may not be) additional loss in the value of additional >>>plies. >>> >>>Far more surprisingly (to me at least) is that the number of fresh ideas do not >>>drop off. IOW, if the program liked one move at ply 10, and another at ply 11, >>>and yet another completely different one at ply 12, they can just keep coming up >>>with new moves that have not been considered best at deeper plies. This one is >>>(to me at least) both astonishing and counter-intuitive. Obviously, it can't >>>possibly find more fresh ideas than the number of possible moves! >>> >> >>I need to go back and re-read the "Crafty/Dark Thought Go Deep" articles. >> >>I hope that "new best moves" were only counted if the evaluation also changed >>significantly. If the change was just a few centipawns, then I think it's >>misleading to report the new move as "better". > >Why would you want to call such moves "not better"??? _many_ moves made by >today's engines are just "slightly" better than other moves that would be >made at shorter time limits. But either you believe that .01 is better, or >you have to ignore evaluations completely. > Guess it depends how much faith you have in your eval. For mine, it sure seems that anything below ~5 centipawns is pure noise. But I have a pretty crappy eval... :( > >> >>This stuff interests me, because I fundamentally believe that playing strength >>must diminish with each additional ply. This topic was discussed a couple of >>months ago, and I was surprised that many people here don't agree. >> > > >The problem is that the only "old" evidence was self-play with varied depth. >Which is probably not a good test, since small changes are often magnified in >self-test play, while at other times small changes have no effect at all. > >New evidence suggests that at least thru 15-16 plies, things are still picking >up with each additional ply... > By "picking-up", do you you mean linear increase in playing strength? >Which you believe is up to you... > >Neither is exactly overwhelming evidence... > >DB did make a statement however, with its 17 ply searches. DT at 10-12 plies >got destroyed by Kasparov. DB at 15-18 plies played far differently. > True, though some of that was due to eval improvements. To be clear, I totally accept the fact that extra plies give increased strength, I just find it impossible to believe that this effect doesn't gradually diminish as you get deeper and deeper. --Peter
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