[EM] Reversal Software output 6/9/1999

Markus Schulze schulze at sol.physik.tu-berlin.de
Fri Jun 11 02:36:04 PDT 1999

Dear Blake,

you wrote (10 Jun 1999):
> > "Marg" is the Condorcet(Margins) variation.
> Calling this method Condorcet seems to be an error started on this
> list.  I'm going to refer to Minmax to refer to the same method since
> this term is used in academic journals.  I use Minmax(Margins) to
> refer to the Marginal variant.

I agree with you. There are lots of different interpretations of
Condorcet's wordings. And that interpretation that is used in this
list doesn't seem to be a justifiable one.

You wrote (10 Jun 1999):
> 1.  Why is it useful to have truncation resistance, if anyone who
> would leave candidates unranked can avoid the punishment by simply
> randomly ranking those candidates?  This seems like something intended
> to trap the gullible.

This would have been an argument against votes-against only if it had
been true that a voter could avoid the punishment by simply randomly
ranking the otherwise unranked candidates.

It has already been discussed that randomly ranking the otherwise
unranked candidates is a useful strategy only if the winner of the
elections is always that candidate whose highest number of votes
against in any pairwise comparison (= win or defeat) is the smallest.
But for every other election method that uses votes-against instead of
margins this is not a useful strategy.

You wrote (10 Jun 1999):
> 2.  Why would anyone use truncation as a defensive strategy if it
> tends to hurt their chances of winning, and the defensive strategy of
> voting a reverser last is available?

Voters don't tend to use order-reversal. But they tend to truncate
if they have to fear that an additional ranking could hurt their
already ranked candidates.

The aim of the use of votes-against instead of margins is to
minimize the probability that a voter could be punished for making
an additional ranking.

You wrote (10 Jun 1999):
> VA seems like a very strange method to me, an attempt by Mike
> Ossipoff to combine Approval and Concorcet.  In other methods, a
> sincere vote is the best (or at least equal to the best) vote when no
> strategic information is known, and then as knowledge is picked up,
> strategic possibilities result.  The winning-votes-only methods are
> unique in that a sincere vote isn't always the best vote even when NO
> information is known.

It is not true that Ossipoff's VA is the unique election method
for which a sincere vote isn't always the best vote even when no
information is known. The problem is that other people don't
discuss the problem of equal rankings.

Example 1: If IRO is used then it is a useful strategy to give
different rankings to your most favorite candidates even if you
like them equally.

Example 2: If "first past the post" is used then it is a useful
strategy to vote for only one candidate even if you don't have
a unique favorite candidate.

Markus Schulze

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