Does VA Schulze violate SEC?

Markus Schulze schulze at
Fri Oct 2 11:23:41 PDT 1998

Dear Blake,

you wrote (02 Oct 1998):
> I think you're mistaken about Schulze and Tideman because both of
> these methods are identical to Condorcet(EM) in the 3 candidate
> case.  So, if you agree that Condorcet(EM) encourages random-fill
> and violates SEC, then the same must be true of Schulze and Tideman
> for three candidates.  Because your argument would seem to apply
> to three candidates examples as well as any others, I have to
> conclude that it includes an error.  Furthermore, I don't see
> why adding additional candidates beyond three would fix these
> problems where they exist.

I don't agree. For example: When I say, that the Copeland method
can be manipulated by cloning candidates, then this means, that
you will never have a disadvantage if you present clones and that
you will sometimes have an advantage if you present clones.

But you say, that already if there is only one situation, where
an election method can be manipulated using a certain strategy,
this election method has this strategical problem.

You wrote (02 Oct 1998):
> Remember, that in Schulze increasing the pair-wise
> victories against candidates is the most likely way to
> increasing the best beat path against them.

This is not true. By ranking the less favourite candidates,
the worst beat-path from a more favourite candidate to a
less favourite candidate could be increased. But it could
also happen, that -by ranking the less favourite candidates-
the worst beat-path from a less favourite candidate to a
more favourite candidate is increased (especially if the
worst beat-path from this less favourite candidate to that
more favourite candidate contains other less favourite
candidates and is limited by the pairwise defeat between
two less favourite candidates).

You wrote (17 Sep 1998):
> Sincere Expectation Standard
> Given that a voter has no knowledge about how others will
> vote, a sincere vote must be at least as likely as any
> insincere vote to give results that are in some way better
> in the eyes of the voter.

I don't think that this standard is important, because if
the voters have no knowledge about how others will vote,
then every election method is strategy-proof.
To my opinion, it should be assumed that every voter has
some information about the probable behaviour of the
other voters.

Markus Schulze

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