Asri-unix.370 net.chess utzoo!decvax!ucbvax!menlo70!sri-unix!jim@RAND-UNIX Wed Dec 30 13:25:23 1981 Re: Limitations of brute-force programs I did some analysis for my dissertation at C-MU a few years ago, and estimated that 13 ply was about the theoretical limit for my TECH program. That involved about 400,000 processors in parallel, organized in a tree structure with appropriate data passing; if memory serves, more would have run into speed-of-light restrictions. That's probably similar to Ken Thompson's 11 ply, since he does more processing at terminal nodes than I did. I don't have a good estimate of the USCF rating for that level, although I believe that it would find incredible tactical ideas that are deep enough to look like strategies. In TECH's class D rating range, I was still getting a linear increase in USCF rating with increases in time, so that adding an extra 1/2 hour to the time control (from 50 moves in 120 minutes to 50 in 150, or 50 in 180) was worth another 80 USCF rating points. Presumably this would start topping out a few rating classes farther up, so that the estimate would no longer be valid. By the way, in TECH it took a factor of 25 increase in speed to search an additional two ply. Where are Ken's rating equations recorded? Jim Gillogly ----------------------------------------------------------------- gopher://quux.org/ conversion by John Goerzen of http://communication.ucsd.edu/A-News/ This Usenet Oldnews Archive article may be copied and distributed freely, provided: 1. There is no money collected for the text(s) of the articles. 2. The following notice remains appended to each copy: The Usenet Oldnews Archive: Compilation Copyright (C) 1981, 1996 Bruce Jones, Henry Spencer, David Wiseman.