Does VA Schulze violate SEC?

[Blake Cretney]

Dear Markus,
On Tue, 06 Oct 1998 22:01:01   Markus Schulze wrote:
>The problem with Condorcet[EM] is the fact, that the random-fill
>strategy _always_ works. The random-fill strategy cannot
>back-fire. That means: A voter is _never_ punished for using
>this strategy, but _sometimes_ rewarded for using this strategy.
>
>I would never have criticized Condorcet[EM], if the random-fill
>strategy had worked only on average.
Here is an example of random-filling back-firing with
Condorcet[EM]

11 A
24 B A C
25 B C A
39 C A B
1 C -- this voter is considering using the strategy


Sincere
   A   B   C
A  X   50  35
B  49  X   49
C  65  40  X

So the votes against matrix is
   A   B   C
A  X   50  0 
B  0   X   49
C  65  0   X
   65  50  49
The condorcet winner is C

Now, if C uses random-fill

11 A
24 B A C
25 B C A
39 C A B
1 C B A - B A was the random choice

Sincere
   A   B   C
A  X   50  35
B  50  X   49
C  65  40  X

So the votes-against matrix is
   A   B   C
A  X   0   0 
B  0   X   49
C  65  0   X
   65  0   49

B is the winner.

So random-filling can back-fire.  That doesn't mean it isn't a good
strategy.  It usually works, and doesn't require any strategic
information, but it can back-fire.

I don't understand why you aren't more concerned with the average
effect.  What if a method had the rich-party problem, but only on
average?  It could sometimes back-fire but usually would help to
run more candidates.  I would find such a method totally unacceptable.

Blake


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