[EM] Smith//Score ?

[Kristofer Munsterhjelm]

On 24.01.2022 21:51, Daniel Carrera wrote:
> Could Smith//Score be the ideal strategy-resistant Condorcet method?
> 
> The ballot would look like a Score ballot. To process the ballots, the
> scores are converted into rankings (equal rankings allowed), and the
> highest scoring candidate inside the Smith set is elected.
> 
> I'm hoping to make a Condorcet method that is very resistant to
> strategy. It's not 100% resistant ---- you can devise an example where
> there is a unique CW and a group of voters alter their ballots to
> produce a different CW that they prefer. Fair enough. But in general the
> voter has to contend with the fact that Score gives you a clear
> motivation to put your preferred candidate on top and your least
> preferred candidate at the bottom. Trying to alter the Smith set by
> ranking Y>X when you really prefer X>Y is a strategy that could work,
> but it could also backfire if X was going to get to the Smith set
> anyway. My intuition is that any strategy that works for Smith//Score
> (and they do exist) should also work for any other Condorcet method. So
> in that sense, this may be the most strategy-proof Smith-efficient
> Condorcet method.

I would guess that this would be vulnerable to burial, and that it would
be broadly similar to Smith,Borda -- although that's just a hunch. I'd
be curious to what your simulator would say about its strategy
resistance :-)

I think that an advanced Range-based method would need to acknowledge
the inherent ambiguity in VNM utilities (mainly, that we don't know how
the voters' utilities are affinely scaled to become ratings). Plain
Range does not, and this is what lets it get off with IIA compliance de
jure while not being independent of losers de facto.

-km