Author: Ed Schröder
Date: 00:35:50 01/31/02
Go up one level in this thread
On January 30, 2002 at 23:21:35, Robert Hyatt wrote: >On January 30, 2002 at 12:52:14, Ed Schröder wrote: > >>On January 30, 2002 at 09:43:49, Vincent Diepeveen wrote: >> >>>Hello, >>> >>>I would like to adress some major nonsense about search depth >>>deep blue. >>> >>>First of all, we know that deep blue was doing only fullwidth >>>with loads of extensions. >>> >>>a) 12(6) doesn't mean they searched 18 ply. It means they searched >>> 12 plies fullwidth from which 6 ply in hardware >> >>Agreed Vincent. 18 plies brute force is impossible. 12 plies brute force fits. >> >>Ed >> > > > >based on what? > >Cray Blitz, using null-move R=1, non-recursive (one null move along any >path, period, which made the search go about 25% faster overall was quite >capable of searching 12 plies. It searched 10 plies at 200K nodes per >second. DB was only 1000 times faster. Could it _really_ only search >2 plies deeper? > >I don't think so... Is this really you Bob? I have seen Cray Blitz playing, Mike Valvo in ecstasy calling through the microphone to the participants and spectators, "Cray Blitz is hitting the 9th ply folks!". And all the programmers trembled all over, myself included, gee 9 plies, who can win from that hardware monster. We are talking about Munich 1986, Cray Blitz was considered somewhat faster than Hi-Tech from Hans Berliner. Hi-Tech searched 8 plies average in the middle game and so did Cray Blitz. Been there, seen it. Hi-Tech was able to get a 100K NPS, you somewhat higher, period! With a 100K NPS you typically search 8 plies (brute force!) in the middle game and not 10-12 plies as you imply. Say 200K is good for 8 plies average, being 1000 x faster with a branching factor of 4 gives: 4x4x4x4x4 = 1024 -> 5 extra plies. So with 200M NPS you might be able to search 13 plies brute force in best case. Subtract a couple of plies (1 to 3) for the way DB did singular extensions and the picture fits, that is: DB was searching 10-12 plies as the log files confirm. This 12(6) isn't 18, you must have misunderstood its meaning. Ed
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