[EM] "scored condorcet", etc

Kevin Venzke stepjak at yahoo.fr
Tue Nov 22 14:38:06 PST 2005


--- Rob Brown <rob at karmatics.com> a écrit :
> I don't question that meeting lots of criteria is good, but sometimes I
> question
> whether some of the people on this list tend to see things in such black
> and
> white terms that they are really missing some important points.  For
> instance,
> with regard to, say, the "clone independence" criterion:  is it possible
> that
> two methods both technically fail this criterion, but that one does a
> whole lot
> better than the other on it?  For instance, plurality utterly fails this.

Actually plurality only fails half of it. Plurality isn't sensitive to
cloning losers.

> Minmax....seems to me that it would only affected by clone candidates in
> the
> most contrived situations.  I think that saying that something "fails",
> without
> saying "how badly it fails", is misleading.

Ok. MinSum fails clone independence "badly."

MinMax is halfway decent on clone independence because 1. It is completely
insensitive to cloning losers, and 2. Only regarding the greatest loss
means the number of losses (and the number of candidates) is not so

In MinSum, if A defeats B, cloning A always hurts B's score. I don't
think this will be acceptable.

> So if MinMax (or the "MinSum" method I proposed) fails some criteria, but
> "only
> by a little bit", 

MinSum is identical to MinMax(margins) when there are only three
In my opinion, MinMax(margins) isn't usable. I don't find that it fails
criteria "only by a little bit."

>while having other desirable properties that can make
> it more
> "marketable" (i.e. you can actually explain how it is tabulated to
> regular
> people in a way they will understand, and show the results in a way they
> will
> understand), I think that could far outweigh its technical imperfections.

I understand that marketability/explicability is important. But is MinSum
really that great here? I think it would be easier to explain MinMax(wv)
(which satisfies plurality and fails minimal defense "only a little").

> Now, with electing a single candidate, things are different, but
> tunabilily
> could still be valuable.  Here is an example:
> Say one election method tends to pick a non-controversial, middle ground
> candidate.  Someone that doesn't offend anyone but isn't necessarily
> loved by
> many people either.
> Say another method tends to favor a candidate that is strongly favored by
> many,
> disregarding whether that candidate is despised by a few.

I don't think this kind of method really exists.

> Now, wouldn't it be nice if you could, when writing a new constitution or
> by-laws, decide the exact balance that is desired, to encourage harmony
> while
> also allowing for healthy debate?  Rather than having to say "should we
> use
> beatpath or minmax or approval or IRV or plurality?", they could say
> "we'll use
> the Tun-o-matic system with the harmony factor set to .7".

Well, if we're going to use something so complicated as a tun-o-matic
system with harmony factors, it should make little difference whether
MinSum (for example) is easy to understand on its own.

Kevin Venzke


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