Le jeudi 8 février 2007 22:09, Sylvain Gelly a écrit : > > It seems i was ambiguous: I was speaking of the simulation player too. > > What i meant is a random simulation player is not biased, whereas a "better" > > simulation player is biased by its knowledge, and thus can give wrong > > evaluation of a position. > I think we have to start defining what the bias. For me the bias is > the difference between the expected value of the outcomes of playouts > by the simulation player and the "real minimax value". In this > definition the uniform random simulation player is VERY biased and > gnugo much less. OK, by i used "bias" in common sense, to mean that the "strong simulator" has preferences for some moves, and doesn't consider them equally, or worse doesn't consider some moves. So it will miss some good points due to its knowledge, whereas the random player will find the move.
> > > A trivial example is GNU Go: its analyze is "sometimes" wrong. > Of course, if not computer go would be solved :-). > > > Even if it is obviously much stronger than a random player, it would give > > wrong result if used as a simulation player. > Hum, are you sure? I m 100% sure of this :-) > I think that GnuGo with randomisation, (and much > faster of course) would make a very good simulation player (much > better than any existing simulation player). Even with randomization, GNU Go considers only a few dozen of possible moves, and makes systematic errors. Some times ago Rémi Coulom asked for "positions illustrating computer stupidity" (2006-11-22) http://computer-go.org/pipermail/computer-go/2006-November/007107.html and GNU Go provided some nice examples where its (wrong/misunderstood) knowledge induces a failure in play. One very impressive was GNU GO 3.6 not invading where obviously it is possible to invade (Steven Clark 2006-11-27) http://computer-go.org/pipermail/computer-go/2006-November/007184.html > But a weaker player than GnuGo can make an even better simulation player. yes. > > > David Doshay experiments with SlugGo showed that > > searching very deep/wide does not improve a lot the strength of the engine, > > which is bound by the underlying weaknesses of GNU Go. > Yes, this a similar non trivial result. I think there are more > existing experimental and theoritical analysis of this, though. > Perhaps such an analysis already exist for MC also, it is just that I > don't know. > > > Or maybe i just understood nothing of what you explained ;) > It was not really "explanations", just thoughts. I have no the > solution, just think that it is an interesting question, and that it > may be discussed. May be from a strong explanation of this phenomenon > could come new ideas. > > I understand all these counter examples, I just think that it is more > complicated than that. > > Sylvain I fully agree. Alain _______________________________________________ computer-go mailing list computer-go@computer-go.org http://www.computer-go.org/mailman/listinfo/computer-go/
