Author: Robert Hyatt
Date: 18:36:02 11/24/99
Go up one level in this thread
On November 23, 1999 at 22:53:11, Dave Gomboc wrote: >On November 23, 1999 at 11:59:46, Christophe Theron wrote: > >>On November 23, 1999 at 03:54:48, Ed Schröder wrote: >> >>>>Posted by Christophe Theron on November 22, 1999 at 18:25:35: >>>> >>>>>>Was it better than Sargon II, or just equal? >>>>> >>>>>It was better because Sargon was outplayed by search depth in most >>>>>cases. In that days Rebel was able to look 6 plies deep all very selective >>>>>and much holes involved but very effective playing a program thinking >>>>>just 4 plies deep. >>>> >>>>6 plies on a TRS-80 in the time Sargon took to compute 4? >>>> >>>>I have the old Sargon II for TRS-80 manual just in front of me. A green manual: >>>>"Hayden computer program tapes, Sargon II: A computer chess program by Dan and >>>>Kathe Spracklen". I have kept it as a souvenir (I also have the cassette, >>>>but I don't dare to open the box). >>>> >>>>The manual says that it took 6 minutes (average) to compute to ply depth 4. >>>> >>>>You are saying that in 6 minutes you were able to compute to ply depth 6 on a >>>>TRS-80??? >>> >>>6 plies indeed all very selective but a friend of mine had doubled the >>>processor speed from 1.77 Mhz to 3.5 Mhz. On standard 1.77 Mhz Rebel on >>>40/120 was only able to compute 4 plies and some moves on 6 plies. >>> >>>The first Rebel was a strange animal. I had to re-invent the wheel >>>completely as I had no access to documentation, I wasn't even aware >>>documentation existed. >>> >>>No alpha/beta, no windows, no Q-search, the program could only think >>>in steps of 2 plies. Thus 2,4,6,8 etc. >> >> >>??? >> >>How did it work? Why the always even depth? > >Maybe he had a big odd/even effect. Funny that he didn't choose 1, 3, 5, 7 ... >though. > >Dave Some did. Tony Scherzer (BeBe) only searched odd plies. It wasn't a particularly great idea, because there are plenty of positions where you can do an 8 ply search, but not a 9 ply search, so you end up stuck with a 7 ply result. IE the time required to do N+1 is (today) typically 3 or so. In 1980 when BeBe was built, with no null-move, etc, it was more like 5-6. To do N+2 required 25-36 times as long as N. Which was often unreachable... It eliminated the odd/even effect, but traded it for something that might well have been worse... 1 ply less deep searches...
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