Author: Steve Coladonato
Date: 16:08:30 06/10/02
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On June 10, 2002 at 10:58:41, Robert Hyatt wrote: >On June 10, 2002 at 08:30:01, Steve Coladonato wrote: > >>Is there any significance in the quality of the analysis that is produced when a >>program (Crafty) performs its analysis forward, i.e. starting at move 1, through >>the game vs a program(s) (Chess Tiger, Shredder) that perform analysis backward, >>i.e. starting at the last move. In the annotate command, I set the "margin" to >>be .10 pawns and the "time" to be 90 secs. >> >>Also, can anyone tell me what the recommended environment/settings should be for >>Crafty on Linux? I'm running on a Gateway 733MHz Pentium III Laptop. >> >>Steve > > >Here is the "thinking" about going backward: > >as you back up thru the game, scores from later searches are stored in the >hash table and they propagate back up the game as a result, letting the program >often see some tactical flaw earlier in the game (because it knows about the >tactical problems that occur later in the game first). > >I don't like it. And here is the "why"... > >When you go thru a game in the forward direction, the program will spot any >tactical oversight its search is capable of finding. When it complains that >you made a worse move than necessary, this will be based on its search, and it >will be repeatable across games. > >When you go backward, you hope that the important tree search results stick >around long enough to be used a few moves back in the game, giving you better >scores. But this is based on a lot of serendipity (luck). If key table >entries survive, you get better analysis. If they don't, you don't. This >means that the "analysis" by the engine has a strong luck component in how >accurate it is. > >I personally prefer "consistency" to "spotty genius-like" analysis because >I want the same quality of analysis for each of my games... It makes it easier >to understand what the machine sees. > >Remember that the computer will produce some analysis at the point in the game >where it sees the score drop. Going forward, it will happen at about the >same "depth" each time. Going backward, it will vary significantly... Dr. Hyatt, Thanks for the explanation. The idea of consistency makes a lot of sense. Steve
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