[computer-go] A new pairing system idea for CGOS

[Don Dailey]

I'm not sure all the people here appreciate the beauty of the swiss
system or how it actually works.  It has properties that really lend
itself to being a nice scheduling algorithm.

One property that is very good is that you always play someone with
the same score as yourself.  If you've won 4 games in the tournament,
you will play someone else who has won 4 games.  If you have lost all
your games so far, you will play someone else who has lost all his
games.   That means you will gravitate towards players near your own
strength, a feature that CGOS aspires to.

Normally, you always play the top half against the bottom half within
point groups.  The top player in the tournament would play the top
player in the bottom half in the first round.  After that, you will
essentially have 2 sub-tournaments if you think of this recursively.
A tournament of first round winners, and a tournament of first round
losers.  But in each sub-tournament you again pit the top half against
the bottom half.   The infinite series you mentioned.

As someone pointed out, this is a deterministic algorithm.  I do have
some concerns about this when CGOS stays static for a long period
of time.  A simple solution is to start each tournament with random
rankings.

This of course creates the possibility that you will get situations
like the top 2 players meeting in the first round.  We could take this a
step farther by randomizing the top and bottom half separately.  This
will effectively kill the determinism while preserving most of the
beneficial properties of correct rankings, but not completely.  

For instance you might still get a first round match between opponents
who are very close in strength, which is not what you want in the first
round.  A swiss is designed so that the distance in strength between
opponents should converge in the later rounds assuming no upsets.  Or
looking at if from the other side, it has the characteristic that your
greatest mis-matches occur in the first round, assuming no upsets.  With
each round, the amount of mismatch is cut in half.  

With correct pairings you would almost never get a situation where Mogo
plays random.   Even with randomized top and bottom halves this would
happen only occasionally,  almost soley based on Mogo losing it's first
round game to a player in the bottom half or random beating a player in
the top half, both events are extremely rare.

- Don



   
On Thu, 2006-10-05 at 16:01 -0700, steve uurtamo wrote:
> > The Swiss mechanism won't be visible, it will happen
> > behind the scenes
> > and would be used as a pairing device only.    All
> > you would see is
> > opponent getting paired from round to round in a
> > fair way.
> 
> honestly, i think that this is a great idea.
> 
> it approximates the "infinite sequence of swiss
> tournaments", which means that it becomes a metric
> that is as good as the swiss tournament system.
> 
> s.
> 
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