[EM] Re: CIBR examples, and its CC failure

[Ken Kuhlman]

On 6/9/05, Chris Benham <chrisbenham at bigpond.com> wrote:
> 
> Ken,
> 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. 

Thanks!
-Ken
-------------- next part --------------
An HTML attachment was scrubbed...
URL: <http://lists.electorama.com/pipermail/election-methods-electorama.com/attachments/20050610/c5ce93f5/attachment-0003.htm>