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Re: Constitutional amendment: Condorcet/Clone Proof SSD vote tallying



On Fri, May 23, 2003 at 08:54:32AM +0200, Jochen Voss wrote:
> On Fri, May 23, 2003 at 02:45:30PM +1000, Anthony Towns wrote:
> > Ugh, that's an overcomplicated example. Here's a simpler one:
> Did you read it carefully?

No, I didn't, and since it's so complicated I wouldn't expect to
understand it properly even if I had. I hate complicated examples.

> > Three options, A, B and D (the default option). Quorum is 10. Votes are:
> > 	9 ABD
> > 	4 BDA
> > A defeauts B, 9:4; B defeats D, 13:0, A defeats D, 9:4. A is dropped because
> > of quorum, B wins. One more person votes:
> > 	9 ABD
> > 	4 BDA
> > 	1 BAD
> > A defeats B, 9:5; B defeats D, 14:0, A defeats D, 10:4. A isn't dropped,
> > and wins. Voting "for" B, thus causes A to win.
> The effect in my example is different, and in my oppinion
> much more of a problem.  In short:
> Your example: An option looses, because it fails quorum
> My example: The winner among the interesting options changes
>     because an uninteresting option fails quorum.

There are many criteria you can choose from. One is "independence
from irrelevant alternatives: the order of preferences among the given
alternatives is not affected by alternatives not being voted on"; which
you're violating here. It's true that you have to violate it sometimes,
but we have a trivial excuse to avoid violating it here. The key, IMO,
is the word "irrelevant" - if an option transitively defeats the winning
option, then it's hardly irrelevant, but if an option fails the quorum
acceptability test, or the supermajority acceptability test, it will
never succeed no matter what happens, and is irrelevant.

> > And, as I've already posted elsewhere, you'll note there's no problem
> > at all here if number of votes received is twice the quorum, which,
> > historically, it almost always is.
> This it true.  But then there there is some tradition of getting
> things right :-)

Yes, that's why we're in favour of per-option quorums, which don't
introduce flawed incentives for little reason other than matching
tradition.

Cheers,
aj

-- 
Anthony Towns <aj@humbug.org.au> <http://azure.humbug.org.au/~aj/>
I don't speak for anyone save myself. GPG signed mail preferred.

  ``Dear Anthony Towns: [...] Congratulations -- 
        you are now certified as a Red Hat Certified Engineer!''

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