[EM] RCIPE version 2
km_elmet at t-online.de
Sat Jul 24 14:19:15 PDT 2021
On 7/22/21 5:31 PM, VoteFair wrote:
> On 7/22/2021 6:04 AM, Kristofer Munsterhjelm wrote:
> > How about this?
> > - Eliminate the candidate with the least number of winning subgroups.
> > - If there is a tie, break that tie by IRV.
> > ...
> Isn't the first step basically Copeland's method?
No, because there's no elimination in Copeland (and it doesn't pass
LIIA). It would just elect the candidate/s with the most winning subgroups.
> That's an ugly "method" that fails to look beneath the surface.
> IRV also fails to look beneath the surface, which is why it too is an
> "ugly" method.
That leads me to wonder which is the case.
You said you couldn't replace the IRV tiebreaker with minmax elimination
because IRV is cloneproof and minmax is not -- that clone independence
was important because it "protects against money-based vote splitting
tactics". So I found something that invokes IRV's clone independence
But then clone independence is not important after all because the
methods are ugly. I can't quite determine whether clone independence is
important or not.
> > But again, the ungrouped mechanic is not cloneproof.
> Being cloneproof is not a goal. The goal is to have a very small failure
> rate for clone independence.
Then you could check the alternatives by that metric. A method seeming
ugly may not necessarily have any bearing on the rates of failure.
> Also, electing the Condorcet winner is not a goal. The goal is to have a
> very small Condorcet criteria failure rate.
> To repeat my concern, attempting to get a zero failure rate will cause
> other kinds of failure rates to increase.
That's true. You implicitly need some kind of valuation of the different
failure rates. For instance, if you want LNHarm and LNHelp, you have to
give up either monotonicity or mutual majority. Which it's going to be
depends on what values you place on the different criteria.
The same would hold for rates. Say you want to find the method that
minimizes w * x, where x is the rates of each failure type
(monotonicity, vote splitting, teaming, crowding, favorite betrayal...).
Then the weights of the w vector provide a measure of indifference: how
much of failure type 1 is an acceptable trade for one unit of failure
Or to put it differently: if the method insists on a zero failure rate
for Condorcet loser, why shouldn't it insist on a zero failure rate for
Condorcet winner, say? And, equivalently, if "merely a low rate of
failure" is good enough for the Condorcet criterion (or say, clone
independence), why is it not good enough for Condorcet loser?
> I'm still willing to consider improvements, but it needs to find a
> balance between what voters can understand -- both through an animated
> video and through words -- and what yields low failure rates.
> Again, thank you Kristofer for applying your clear understanding to this
> revision from RCIPE 1 to RCIPE 2.
You're welcome :-)
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