[EM] Participation & SARC

[Markus Schulze]

Dear Mike,

you wrote (9 May 2000):
> Markus wrote (9 May 2000):
> > There was the discussion whether sincere or sophisticated voters
> > should be presumed. You (5 May 2000) and Steve (5 May 2000)
> > wrote that sophisticated voters should be presumed because it is
> > unrealistic for real elections that the voters vote sincerely.
> > I wrote that sincere voters should be presumed because -unless
> > additional presumptions about the used strategies are made- it is
> > not unique how a sophisticated voter with a given opinion votes
> > (5 May 2000).
>
> I'm not sure what you mean by "It is not unique how a sophisticated
> voter...votes", but so what? The criteria that deal with
> strategic voting don't "presume" how someone will vote.

Example: Very frequently it is presumed that if Approval Voting is
used then the voters (if they are sophisticated) vote in such a way
that a Condorcet winner (if one exists) will always be elected. If
this presumption is true then even Approval Voting doesn't guarantee
that a like-minded group isn't punished for going to the polls and
voting in a sophisticated manner. The proof of this fact is very
similar to Moulin's proof that Condorcet and participation are
incompatible.

What do you think?: How does a sophisticated voter votes if Approval
Voting is used?

Markus Schulze
schulze at sol.physik.tu-berlin.de
schulze at math.tu-berlin.de
markusschulze at planet-interkom.de