Although the number of games explored is very limited relative to the total number of possible games, those games are in some sense representative of what happens if you start with a particular move. That's why they can help to create a ranking that tells you something about which moves are better than others. The move to heavy playouts is about making the sample games even more representative so that they yield more useful information.
Others on this list have reported in the past that the randomness is actually very important. Playouts that are very heavy, no matter how "clever" they are, actually reduce the performance because they narrow the number of games too much. You should also read up on the "all moves as first" (AMAF) technique. This is even more surprising because it attributes the outcome of a random game to every move of that colour during the random game, as if that was the move that had been played first. This generates information to help rank the moves even more quickly. Oliver On Tue, Jul 7, 2009 at 2:15 AM, Fred Hapgood <hapg...@pobox.com> wrote: > I have a really basic question about how MC works in the context of Go. > > Suppose the problem is to make the first move in a game, and suppose we > have accepted as a constraint that we will abstain from just copying > some joseki out of a book -- we are going to use MC to figure out the > first move de novo. We turn on the software and it begins to play out > games. My question is: how does the software pick its first move? Does > it move entirely at random? Sometimes it sounds that way MC works is by > picking each move at random, from the first to the last, for a million > games or so. The trouble is that the number of possible Go games is so > large that a million games would not even begin to explore the > possibilities. It is hard to imagine anything useful emerging from > examining such a small number. So I'm guessing that the moves are not > chosen at random. But even if you reduce the possibilities to two > options per move, which would be pretty impressive, you'd still run out > of your million games in only twenty moves, after which you would be > back to picking at random again. > > What am I missing?? > > > > > http://www.BostonScienceAndEngineeringLectures.com > http://www.pobox.com/~fhapgood <http://www.pobox.com/%7Efhapgood> > > _______________________________________________ > computer-go mailing list > computer-go@computer-go.org > http://www.computer-go.org/mailman/listinfo/computer-go/ >
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