Democratic symmetry (fwd)

[Markus Schulze]

REVERSAL SYMMETRY

I have to agree with Donald Saari, that reversal symmetry is
a very important criterion. But actually, many very good
election methods meet reversal symmetry (e.g. the Tideman
Method).

ROTATIONAL SYMMETRY

I have to admit that I don't see what Saari's rotational
symmetry has to do with rotational symmetry. In so far as
reversal symmetry means that the ranking of the candidates is
reversed when the preferences of each voter is reversed, I would
have expected that rotational symmetry means that when each
voter changes his preferences in the same cyclic manner then the
ranking of the candidates is changed in the same cyclic manner.

Is there a simple way to see that Saari's rotational symmetry
really is a symmetry criterion?

Markus Schulze