Hi Chris,
"to the extent that the failures of these criteria are tolerable" means that certain extreme
candidate cloning issues shouldn't ultimately be problems in an assembly environment.
If a majority party has three candidates (and the members of this party support those candidates
to the extent that they would be willing to rank them together on a ballot) it should never
happen that the majority loses a vote (???) to a minority proposal. This does not mean that the
outcome was actually independent of the clones, just that a bizarre outcome should not result
from them.
And on the other side, a minority party can't possibly prevail in an assembly environment just
by making a large number of similar proposals.
The low value (that I perceive) of "total" clone independence is not just in the cost but in
what it actually gets you. That is, you only need one vote that denies that two candidates are
clones, and suddenly clone independence guarantees no longer apply to this scenario. (Most
serious clone-proof methods will still behave well, but it's trivial to define a method where
the usefulness of clone independence breaks down quickly given some noise. Like DSC, even.)
To me the cost is mostly simplicity, but also sometimes other criteria. I like C//A, which is
very simple but fails clone-winner. That doesn't really bother me. There's also ICA, which is
not so simple, but satisfies FBC. Clone-proof methods that satisfy FBC can't do much with
pairwise comparisons.
Kevin
----- Mail original -----
De : C.Benham <***@adam.com.au>
À : election-***@lists.electorama.com
Cc :
Envoyé le : Jeudi 6 novembre 2014 8h10
Objet : Re: [EM] Condorcet methods - should the cycle order always determine the result order? (Toby Pereira)
Kevin,
"I think that this principle almost implies Condorcet (some worthwhile edge cases might
exist I think), and I think it implies clone-winner and clone-loser to the extent that
the failures of these criteria are tolerable.
Total clone independence is too expensive for me to insist on,..."
Can you can clarify your phrase "to the extent that the failures of
these criteria are tolerable"?
What is it that we have to give up for "total clone independence" that
in your view makes it "too expensive"?
Chris Benham
Hi,
________________________________
Envoyé le : Mercredi 5 novembre 2014 15h29
Objet : Re: [EM] Condorcet methods - should the cycle order always determine the result order? (Toby Pereira)
Post by Toby PereiraBut this also makes me wonder generally - are there any sensible
cloneproof ranked-ballot systems that aren't Condorcet methods? IRV is
cloneproof, but is it sensible? Is there anything else?
Perhaps one of the descending coalitions family? DAC, DSC or HDSC.
They're cloneproof, but to determine whether they're sensible, you'd
probably need a more exact definition of what "sensible" means. They're
a lot closer to Plurality than Condorcet is.
Yes, I think those are probably the most fitting suggestions even if they're not that
http://permalink.gmane.org/gmane.politics.election-methods/18829
........................Bucklin.............................
............................................................
............................................................
..............................DAC...........................
...................WV.......................................
............................................................
............................BklnVar.........................
..............C//KH.........................................
............................................................
.............KH.............................................
.................C//IRV.....................................
.......................QR...................................
...................................DSC......................
..................IRV.......................................
.......................................FPP..................
Methods on the east side (DAC/DSC) don't seem to get invented very often. You probably
won't get much more unusual than these without failing the Plurality criterion.
My own basic principle for sensibility is that the winner of the election should be
one of those candidates who might be the winner if the electorate had been an assembly,
capable of surveying how many voters were available to vote in any given way, and
adjusting votes based on which outcomes might actually be achieved. I think of other
candidates (i.e. those who could not plausibly have won in an assembly setting) as
"unrealistic" winners.
I think that this principle almost implies Condorcet (some worthwhile edge cases might
exist I think), and I think it implies clone-winner and clone-loser to the extent that
the failures of these criteria are tolerable.
Total clone independence is too expensive for me to insist on, and in itself doesn't
even reassure me that there won't be "clone-like" issues. The definition of "clone"
is very strict.
Kevin
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