Author: Omid David
Date: 05:29:24 10/12/02
Go up one level in this thread
On October 11, 2002 at 21:57:34, Robert Hyatt wrote: >On October 11, 2002 at 17:51:27, Omid David wrote: > >>On October 11, 2002 at 11:51:13, Robert Hyatt wrote: >> >>>On October 11, 2002 at 07:43:40, Uri Blass wrote: >>> >>>>On October 11, 2002 at 07:12:34, Vincent Diepeveen wrote: >>>> >>>>>On October 11, 2002 at 04:08:49, Uri Blass wrote: >>>>> >>>>>Isn't his article clear enough yet? >>>> >>>>Bob Hyatt still claims that it was 12 plies software and 6 plies hardware >>>>so I prefer to hear an answer directly from Hsu. >>> >>>I agree. But _I_ don't claiam _anything_ except that members of the DB team >>>specifically told me that 12(6) means 12 plies in hardware, 6 in software. I >>>even posted the excerpt from the email that specifically said this... >>> >>>That is _all_ I have said about it... >>> >> >>No matter what they say, even under extreme theoretical conditions it is >>*impossible* to search 18 plies of brute force in chess, without any type of >>forward pruning whatsoever, and no hash tables. > > >However, they have _never_ said they didn't use forward pruning. They have only >said "we don't use null-move for forward pruning" and nothing else. And they >have >slowly leaked details. But they pretty much had to since I had gone over their >log >files and discovered that theyt had a _very_ good branching factor, too good for >pure >alpha/beta alone... > Interesting... What was the average branching factor based on the logs you reviewed? > > >> >> >> >>> >>> >>> >>>> >>>>> >>>>>reporting a 12.2 average search depth fullwidth. >>>>>I guess you never searched with a decent program fullwidth >>>>>with extensions. If you did, you would understand that >>>>>getting 12.2 ply fullwidth with loads of extensions is already nearly >>>>>impossible. Every extended line is searched to the full depth, >>>>>no pruning happens! >>>> >>>>I agree that 12.2 plies with a lot of extensions and no pruning is impossible >>>>for normal programs and also is impossible for deep blue in case that >>>>there were real 6 more plies in the hardware. >>>> >>>>The only case when it may be possible is if the 6 more plies in the hardware are >>>>real selective search and it means more pruning than null move with R=3 and in >>>>this case the 6 plies in the hardware may be eqvivalent to only 2 plies in >>>>software because of big probability to miss things. >>>> >>>>> >>>>>The interesting 2 questions are >>>>> a) did DB use 'no-progress pruning' in SOFTWARE (we know >>>>> already it used it in hardware). >>>> >>>>They explained in the article that they did not want to take risks of missing >>>>something in the first plies so it is clear that they did no pruning in the >>>>first 12 plies. >>>> >>>>If they did some pruning in the software it is clearly after it. >>>> >>>>I do not know what is exactly no progress pruning. >>>>Is there a difference between it and null move pruning? >>>> >>>>Is no progress pruning more aggresive than null move pruning? >>>> >>>>Uri
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