Author: Eran
Date: 16:29:36 03/19/01
Go up one level in this thread
On March 19, 2001 at 16:14:58, Bruce Moreland wrote: >On March 19, 2001 at 14:34:50, Frank Schneider wrote: > >>On March 18, 2001 at 18:15:26, Bruce Moreland wrote: > >>>This is a bug, in my opinion. >> >>Why do you think so? > >The program drew right out of the opening with a weak player. It's obviously a >bug of some sort. > >>> It is easy to set a program so it won't do this, >> >>how? Make the program believe the opponent if he tries to repeat? > >It works just fine if the goal is to draw in the opening. If that's the >intended effect, I have no answer. > >I think it would be fixed if the program wouldn't try to draw in the opening. >It would be possible to fix the problem by understanding that the position was >an opening position and was something that was normal and not that bad. Unless >of course it was that bad, in which case this is a book bug, which is still a >bug. > >A quick fix along these lines would be to make the contempt factor a pretty >large negative number in the opening. > >Another more comprehensive fix would be to not score positions played on the >board as draws unless they have been played twice. > >I remember hearing about a commercial program, some time ago, that if you played >1. e4 e5 2. Nf3 Nc6 3. Ng1 against it, would play 3. ... Nb8, trying to draw, >because it had an asymmetrical eval that scored most opening positions as >negative from its point of view. Even two tempi up it thought it was worse. > >Other than the obvious fix of the asymmetric eval, a way to fix this problem >would be to simply not recognize that 3. ... Nb8 is a repetition, because it has >only occurred once. > >The argument against this fix has always been that the program might miss some >real repetitions, but I think this argument is poor. If the program is the one >repeating the position unnecessarily (because it doesn't know that the position >has already happened once), then it will have a chance to do better before >allowing a third rep. If it's the opponent who is try to draw by repeating the >position, to hell with them. If the program can find something that preserves >play, I say that it should. > >My program scores any position that occurs twice along a search branch as a >draw. It scores any position that occurs twice in the list of played positions, >plus once in a search branch, as a draw. It does not score a position a draw if >it occurs once in the list of played positions and once in a search branch. >This has always worked fine. It even has the added benefit of allowing other >operators to think that my program is going to throw away a win by repeating the >position, just because it does it once. > >This fix is also useful against humans who mess up. If a human has a win in a >position, and misses it, if you do draws Stefan's way you may play into the >position and allow them to find the win the second time. If you do things my >way, you'll never do this. > >Example: I'm at -2. My opponent makes a reversible move that allows me to make >a reversible move that I score as -1. They then realize their error and undo >their move. A lot of programs will undo their own move, in order to get back to >the "drawn" position that is really -2, rather than continuing along the -1 >line. Mine won't. > >This is a practical case. I saw it in one of the first ICC rated games my >program played. > >>Frank >> >>P.S.: is Pat still slow? > >Pat still has all of that video, but he's kind of a weenie. His email address >is patw@microsoft.com if you want to kick him a little. > >bruce > >>>and even if you choose to keep things the way they are, Shredder's scoring >>>shouldn't allow it to call it a draw in a game with that much play left. >>> >>>bruce I tried the contempt factor to -30 or +30 and it still did not work! Eran
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