On Sun, Jun 7, 2009 at 11:02 AM, steve uurtamo <uurt...@gmail.com> wrote:
> > The handicap system is imperfect anyway, it's almost > > a coincidence that it works as well as it does. > > okay, this sounds like chess bias. the handicap > system *defines* the difference in skill levels in go. > it's a coincidence that something like ELO can match > fairly well to stones. not the other way around. Both systems are badly broken because they both make simplfying assumptions that are just not true. It's just that the ELO systme is less broken. Here is why the handicap system is broken. We can talk about how the ELO system is broken in another discussion but it is too. At 1 or 2 stones difference, the handicap system works well. At greater handicaps it's skewed. The "coincidence" that I'm talking about is that it works to a reasonable degree at larger handicaps. The handicap system is based on the idea that no matter what your level of play, you can give 7 stones to a player 7 stones weaker. Everyone knows this is not true. It is very accurate at low handicaps, and progressively less accurate at high handicaps (as well as high levels) so for instance a professional player with a relatively low professional ranking does not need as many stones as indicated by his opponents ranking to beat another professional WHO IS SEVERAL RANKS HIGHER. Is this not correct? When I say it's imperfect, that is what I am talking about. There is nothing wrong with defining 1 stone handicap as a "rank" and I don't view that definition as imperfect and that is a reasonable basis for defining the ranking system in GO. What's imperfect is the assumption that 9 stones makes it a perfectly even match if you are 9 ranks apart no matter where along the scale you are. If you wanted to know what handicap is needed to win a match at various handicaps from beginner to world chamption, you would need a 2 dimentonal table lookup because it's not as simple as just taking the difference in their rankings. With the table lookup and a huge amout of data to back it up, you would have a predictor as good as ELO. Does that clarify what I meant when I said the handicap system is imperfect? As we discussed many times on this forum and in private email, a one stone handicap has a different meaning at different levels - it's just an awkward system to deal with mathmatically on a go server for computers where wild mismatches will be common. > > the fact that chess doesn't have a fine-grained way to > handicap a game, in fact, the fact that most games don't, > doesn't mean that it's hard to deal with. There are simple ways to deal with it. One could simply increase or decrease your rank as soon as you start winning or losing you games at your current handicap level. We don't need ELO for that and it's simple to do. What I see on most servers and in this modern day and age is a move away from the centuries old system, not an embrace of it as being superior. Of course I understand there is a sentimental attachment to it. It was like this in chess many years ago when the old fashion descriptive chess notation was replace in the USA with algebraic notation in order to stay with the modern world and to many people it was just not chess anymore. > > my guess is that any go playing program that doesn't > depend upon an opening book for a lot of its strength > is going to adapt just fine. experiments between players > of different CGOS-measured strengths could find this out for > sure -- time for another set of experiments? i'll donate some > cpu time. It took a lot of work and energy to do these studies - I'll have to think about this one. Of course they would adapt if that was the system. Even if this idea was not good for current MCTS programs they would adjust is that was what was required to do well in competition. > > > if it helps to encourage the authors, just keep in mind > that winning with handicap is extremely convincing > evidence to "regular go players" that one player is much > stronger than another. plus, it takes exponentially fewer > games to determine that difference. > > with a logarithmic (in range of handicap, say, +/-6 stones) > number of games you could get a very accurate view of > the strength difference between two players. say, take > best of 2 out of 3 at each test level and do binary search. > > some go clubs just keep track of the relative difference > in stone strength between pairs of players, requiring, say, a > 3-win streak by one player to adjust the handicap by a > single stone. > > alternatively, you can (somewhat cheesily) map ELO > to handicap and vice-versa for a limited range of ELO > and handicap. Like I say, a table will do it, and I believe some kind of formula could be fitted to the data. - Don > > > s. > _______________________________________________ > computer-go mailing list > computer-go@computer-go.org > http://www.computer-go.org/mailman/listinfo/computer-go/ >
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