Author: Stephen A. Boak
Date: 19:35:03 11/17/00
Go up one level in this thread
On November 17, 2000 at 12:50:36, Steve Coladonato wrote: >I lifted this question from the following site: >http://correspondencechess.com/campbell/ham/fr_hambl.htm > >Does anyone know what the answer may be? > >> >Fritz 6a continues to merely chase my pieces around without any plan in sight. >The chess engine calculated for 21 hours and 30 minutes to a depth of 28/46 ply, >at an average speed of 387 kilonodes/second. Unfortunately, it favors its >position by 2.66 pawns. > >The computer operator, Franklin Campbell, set the chess engine to display only >the best line. Given its alpha-beta algorithms, this is its most efficient mode. >However, Fritz 6a recently began to display two or more moves with almost >identical evaluations. Franklin wrote that it's "as though it couldn't make up >its 'mind' about what was best". Franklin also noted that while it's set to find >the best single line, it sometimes displays 7-8 lines, usually with the same >starting move. > >My guess is that this phenomenon is caused by the fact that many lines >transpose. If transpositions are involved they would have the same evaluation if >the transpositional line were the main line, and a slightly lesser evaluation if >the transposition were a slight deviation from the main line. For example, >Franklin noted that another line that was displayed was 61 Kc6 evaluated at 2.63 >pawns. Thus it perhaps saw 61 Kc6, Kb8 62 Re7, Bd4 (see my commentary to Black's >59th move for more on this line) and 61 Re7, Bd4 62 Kc6, Kb8 reaching the same >position. It may have given this line a lesser evaluation due to its alpha-beta >algorithm, or because in the former line this was a small deviation from its >main line. Of course this is all speculation on my part. I am far from a >knowledgeable source on anything involving computers. Can any readers who are >chess computer experts explain this phenomenon? Please let us know the cause. >< very funny! How expert is the operator and how good is his understanding of Fritz6a? If you accidentally hit the '+' key, more lines will be displayed (n-best mode will toggle to n+1 each time the '+' key is pressed. If you hit the '-' key many times, the n-best mode will reduce to the single best line. Of course, at each ply searched (and perhaps in the middle of a search ply that is not yet completed) it will display the best line discovered so far, scrolling the prior best line upward. Several 'prior' best lines are often seen on the screen at the same time. I'd love to have Fritz6a analyze a comlete game for me, and in the automatic analysis embedded in the file show the n-best moves/lines, not just the top line. However, I believe that is impossible with the current software version. Another possibility--is overnight analysis being used, where the user sets the number of branches desired at each of the first several plys? I don't use this feature, so don't understand it well, but it may produce several lines. Please post any more info that is determined about this 'problem'. I am curious. Thanks. --Steve
This page took 0 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.