[EM] Re: CIBR examples, and its CC failure
kskuhlman at gmail.com
Fri Jun 10 09:07:31 PDT 2005
On 6/9/05, Chris Benham <chrisbenham at bigpond.com> wrote:
> Does CIBR (like plain Borda) meet Participation? (a tall order).
> If not, does it meet Mono-raise (i.e. is it monotonic)?
These are interesting questions, and I'll try to take a look at them in the
future. I'm going to have to give you a rain check for now, for reasons that
will be apparent below.
And a more general question: why do you think its better or more
> important to meet Symmetry than the Condorcet criterion?
Quite simply, I was wrong. Daniel Bishop & Araucaria Araucana tried to help
me understand this, but I was stubborn & it took a couple of days for the
message to sink in. I apologize to them for that.
The primary objective to me is to maximize protection from candidate
dropping effects (I avoid use of the term IIA because of its multiple
meanings--it's also a constraint against possible election methods). The
examples we discussed before show that in some small subset of profiles at
least, symmetry maintenance & candidate dropping protection are
incompatible. In these cases, symmetry must be broken to obtain our goal.
So, CIBR appears to be less than ideal, which stems from the fact that the
weakest candidate isn't necessarily eliminated first. I've managed to work
out a fix, which is relatively straightforward & maintains all of CIBR's
desirable qualities and apparently meets CC. (I haven't been able to find a
failure, but I have no proof.)
I'll post the revised method in the near future.
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