Author: Dave Gomboc
Date: 12:18:09 03/03/00
Go up one level in this thread
On March 03, 2000 at 08:09:47, Robert Hyatt wrote: >On March 03, 2000 at 03:44:48, Dave Gomboc wrote: > >>On March 02, 2000 at 18:26:09, Robert Hyatt wrote: >> >>>On March 02, 2000 at 01:42:43, Ed Schröder wrote: >>> >>>>On March 01, 2000 at 20:52:52, Jonathan Lee wrote: >>>> >>>>>Thanks, Pete on IBM's logic on their selling of chess software. If their >>>>>software was awesome, they already would have a large share against the top >>>>>guns. >>>>> >>>>>Someday said every 18 months the hardware doubles in speed. >>>>>Someone else said IBM's hardware "DB" is 1000 times faster than the 500MHZ PIII. >>>>>In the year 2015, (what a bold prediction) PC's will be as fast as Deep Blue. >>>>>Do the math: >>>>>2 ^ 10 = 1024 (twice the speed 10 times equals about 1000 times faster) >>>>> >>>>>18 * 10 = 180 (18 months multiplied by ten times equals 180 months) >>>>> >>>>>180 months equals 15 years >>>>> >>>>>2000 + 15 = 2015 (We are now in the year 2000; add 15 years and you will get >>>>>2015) >>>> >>>>What about today? >>>> >>>>Nowadays programs hit a deeper ply depth than DB. See the log files >>>>on the IBM site. >>>> >>>>Ed >>> >>> >>>No... you are mis-reading the logs. When you see depth=10/5, that means >>>10 ply (full width + extensions) in the software, another 5 plies + everything >>>but singular extensions in the chess engine. When you look at those numbers, >>>we are getting crushed in search depth. 10(5) means 15 plies full-width, no >>>null-move or anything, + their extensions. >>> >>>This was covered when we were discussing the DB logs. I confirmed this >>>point with two different DB team members to be sure we were understanding the >>>(n) number correctly. Looking at the logs, the hardware searches 4-6 plies >>>depending on the base software search depth. When you see 11(6) that is a >>>full-width 17 ply search, which is awesome. >> >>Double-check that. 11(6): 17-ply search, yes. _full-width_ 17-ply search, I >>don't think so. The top of the software search is full-width, the bottom of the >>software search is selective, and the hardware search is full-width again. At >>least, that is my understanding. The interesting question is how many of the 11 >>in software were full-width... and my recollection is that the answer is not 11. >> >>Dave > > >There is _no_ selective search in DB. They do "selective extensions" in the >software, but _every_ move is searched to at least the depth given. IE if you >see 11(6), then *every* move at the root is searched to at _least_ 17 plies >deep, not counting the capture search. And most are searched deeper due to the >extensions. > >_None_ are searched to less than that depth. DB _never_ had any sort of forward >pruning in the normal search, although it did have a sort of futility cutoff in >the capture search only. > >This is all well-documented. Hsu didn't believe in selectivity at all when >applied to pruning. > >The answer to your question _is_ "11". It's well-documented for DT. Where is it well-documented for DB? I know Hsu didn't like pruning, but by itself that doesn't mean that they didn't do any in DB. Does he say so in his book? My recollection of a conversation with a member of the DB team in 1997 is that there was some selectivity going on in the software search, in the manner that I described above. Dave
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