[EM] strategy problem

[Forest Simmons]

On Mon, 18 Aug 2003, James Green-Armytage wrote:

>
>
> 	Could it be possible to design a version of Condorcet that is more
> strategy-proof than beatpath or ranked pairs? I admit that it doesn't look
> easy. I note in passing that the Raynaud system (repeatedly eliminate the
> candidate with the greatest defeat) does better in my first example than
> sequential dropping / maximin-based systems, although it doesn't help in
> all such examples, and it offers some fairly nasty strategic possibilities
> in other situations, as well as sometimes producing results that are just
> generally counter-intuitive. It may or may not pass Monroe's NIA criteria.
> 	Other than Raynaud, could there be some kind of system with little extra
> boxes for voters to check, or something like that? A multiple-round system
> of some sort? It's an interesting problem.
>

It seems to me that "Approval Completed Condorcet" would be less
vulnerable to this kind of manipulation.

In one version voters rank a (virtual) Minimum Acceptable Candidate along
with the real candidates.  If there is no CW, then the candidate who has
the strongest win over the virtual candidate is the winner.  If the
virtual candidate is the CW, then the candidate (perhaps limited to the
human Smith set) who comes closest to beating the virtual candidate is the
winner.

In this last case, where the Minimum Acceptable Candidate is the CW, the
human winner must humbly acknowledge his lack of "mandate."

In this version no extra check boxes are needed, just one extra candidate,
so ordinary ranked ballots suffice.

I remember that Adam Tarr lost interest in Approval Completed Condorcet
when he figured out that it wasn't completely invulnerable to
manipulation, but he might change his mind with this "turkey raising
chicken game" in mind.

Forest