[EM] Condorcet - let's move ahead

[Markus Schulze]

Hallo,

Steve Eppley wrote (18 Jan 2009):

> MAM satisfies all the desirable criteria satisfied
> by Beatpath Winner (aka Cloneproof Schwartz Sequential
> Dropping--CSSD for short--aka Schulze's method).

Many people consider the Simpson-Kramer MinMax method
to be the best single-winner election method because it
minimizes the number of overruled voters. The winner of
the Schulze method is almost always identical to the
winner of the MinMax method, while the winner of the
ranked pairs method differs needlessly frequently from
the winner of the MinMax method.

For example, Norman Petry made some simulations and
observed that the number of situations, where the
Schulze method and the MinMax method chose the same
candidate and the ranked pairs method chose a different
candidate, exceeded the number of situations, where the
ranked pairs method and the MinMax method chose the same
candidate and the Schulze method chose a different
candidate, by a factor of 100:

http://lists.electorama.com/pipermail/election-methods-electorama.com/2000-November/004540.html

Jobst Heitzig made a thorough investigation of the
4-candidate case. In no situation, the Schulze method
and the MinMax method chose different candidates.
("Beatpath and Plain Condorcet are unanimous in all
these examples!") But in 96 situations, the ranked
pairs method and the MinMax method chose different
candidates:

http://lists.electorama.com/pipermail/election-methods-electorama.com/2004-May/012801.html

There are even situations where the winner of the
ranked pairs method differs from the winner of the
MinMax winner without any plausible reason. See
section 9 of my paper:

http://m-schulze.webhop.net/schulze1.pdf

Markus Schulze