Author: Robert Hyatt
Date: 14:44:06 12/21/99
Go up one level in this thread
On December 21, 1999 at 17:02:53, Greg Lindahl wrote: >On December 21, 1999 at 16:18:27, Albert Silver wrote: > >>That's correct, he says it was done through software: "During the 1997 match, >>the software search extended the search to about 40 plies along the forcing >>lines, even though the nonextended search reached only about 12 plies." He also >>mentions that "The software portion of the search can be arbitrarily selective >>without slowing down the system." > >If you read the beginning of that paragraph, Hsu explicitly says that the 8 >plies of software search included forcing. Hsu doesn't say if the final 4 plies >of hardware search included forcing by droping back to software or not. Given >that the chess chips seem to operate in an embarrassingly parallel fashion, I >would suspect that there was no forcing for those plies. Someone could always >ask Hsu... > Old news. The first 4 plies (+ whatever extensions were used) were done on a single SP processor. The next 4 plies + whatever extensions were triggered were done in parallel on the SP, which (if stated simply) says that the first 8 plies, plus all the extensions, are done on the general-purpose SP hardware. The _final_ 4 plies, plus the capture search were done on the chess processors. The chess processors _did_ do extensions, but not singular extensions. IE Ken Thompson did the usual in-check and recapture extensions in Belle, and the first deep thought (chiptest) chip was nothing more than "belle on a chip". Also, chess is _far_ from "embarassingly parallel". It is one of the more difficult-to-program parallel algorithms, because alpha/beta is a strictly defined sequential algorithm. Doing it in parallel invites a lot of extra work that can't be avoided. >How important is forcing in shallow plies verses deeper plies? That's easy to >examine using a program. > >-- greg Hsu would _like_ to have been able to do singular extensions in hardware. But there was simply not enough space on the chip as things get _very_ complex compared to a simple alpha/beta hardware design... But you have to ignore some of Vincent's ramblings about DB's search depth. I once posted a position where they found a forced win of material OTB vs Cray Blitz, as but one example of their extreme tactical strength. _NOBODY_ found that win OTB, or overnight. Many liked the move, but _nobody_ saw the tactical consequences that were forced. They have done this _many_ times over the years. So I'd say their "11-ply search" is _far_ better than our 14-15 ply searches, no questions asked...
This page took 0.02 seconds to execute
Last modified: Thu, 15 Apr 21 08:11:13 -0700
Current Computer Chess Club Forums at Talkchess. This site by Sean Mintz.