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 handicap accurate at all with professional ranks? I've heard before
that they are 1/4 stone apart.
I am 3k on KGS and I'd say that I win nearly every game that I give
handicap and lose over half the games that I receive handicap. That
would seem to imply that more handicap should be given near my rank.
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.
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