[EM] : Chicken problem (was: SODA and the Condorcet

[Juho Laatu]

On 7.8.2011, at 2.04, Jameson Quinn wrote:

> 
> 
> 2011/8/6 <fsimmons at pcc.edu>
> Jan,
> 
> IRV elects C like all of the other methods if the B faction doesn't truncate.  But IRV elects A when the B
> faction truncates.  Of course, with this knowledge, the B faction isn't likely to truncate, and as you say C
> will be elected.
> 
> The trouble with IRV is that in the other scenario when the B faction truncates sincerely because of
> detesting both A and C, IRV still elects A instead of B.
> 
> Also, if the A faction votes A>B, then B clearly should win, but does not under IRV. So yes, IRV solves the chicken dilemma, but in so doing causes other problems. (This same argument, as it happens, works against tree-based methods.)
> 
> I still claim that SODA is the only system I know of that can solve the chicken dilemma without over-solving it and making other problems.

I wouldn't say that trees "over-solve" the problem. The tree approach to the chicken problem could be called "explicit clones". That's quite natural. Some candidates just announce that they are clones and that they will support each others. That sounds like a pretty exact solution, not an over-solution.

Do trees "cause other problems" then? They do not allow the voter to support one of the clones without supporting the other. But this is exactly what the intention of the explicit clone approach is. Also the need to declare a branch in the tree could be considered to be a practical problem / increased complexity. And the need to identify the clones is an extra task / problem. But maybe not really. What other (more serious) problems would the trees cause?

Juho




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