Author: Ernst A. Heinz
Date: 20:45:09 07/29/98
Go up one level in this thread
On July 29, 1998 at 18:54:35, Robert Hyatt wrote: >On July 29, 1998 at 13:21:05, Danniel Corbit wrote: > >>On July 29, 1998 at 10:48:44, Tom Kerrigan wrote: >> >>>On July 29, 1998 at 10:06:43, Danniel Corbit wrote: >>> >>>>Let's say, for the sake of jihad, that we define sensible moves in the following >>>>manner: >>>>From a given FEN position, look at what every GM who has ever visited that >>>>position has done. >>>>From the same FEN position, let every top commercial and amateur program examine >>>>that position for 24 hours. >>>>At this point, we would have, I suspect, a small list of possible very good >>>>moves, a mid sized list of so-so moves, and a large list of bad moves. >>> >>>Perhaps. >>>I don't know what this would accomplish, and it seems like similar things have >>>been done by people who do opening book stuff. >>>Basically, what you're writing isn't really related to the topic at hand. >>I disagree. It is related, because I believe that an exhaustive search has very >>little value, and a careful analysis of the "ahem" good moves has a very high >>value. >> >>Here is an experiment that will demonstrate my point [I think]. Run any chess >>engine you like against a set of 100 arbitrarily chosen FEN positions achieved >>by at least 3 different GM's at least 6 moves into the game. Analyze the >>position for 7 plys, exhaustive. Analyze the position for 8 ply's exhaustive. >>See how often a move that was not considered one of the top three from previous >>exhaustive searches gets introduced as the new choice. I suspect it will be >>less than one in a thousand. >> >>If that is the case, then exhaustive searching has very, very little value. >> >>We will certainly not be able to search 12 plys exhaustive for a long time, >>anyway. Exhaustive search will therefore never be competitive with Alpha-Beta >>or any other real searching technique. So what is it's value? Only to find the >>rare gem that conventional searching techniques might miss. 99.99999% of the >>bogus games generated by the exhaustive search will be utter crap that even a 9 >>year old novice would not play. > > >Here I have some data. In the "Crafty goes Deep" experiment last year, we ran >such a test with Crafty, searching 347 different positions to depth=15. We >were interested in how often does one more ply produce a different move. The >result? Somewhere in the 20% range which was surprising. In fact, within close >limits, adding one ply changed the PV about 20% of the time no matter whether it >was going from ply 6 to ply 7, or ply 14 to 15. The JICCA has the exact >results, while the raw search output is on my ftp machine... > >Bob Bob, Your paper only mentions searches to fixed depths of 14 plies. =Ernst=
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