Author: Peter Kappler
Date: 19:54:45 05/23/00
Go up one level in this thread
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". 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. >To say the least, it deserves further study. Indeed. --Peter
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