iterated Condorcet checks out

[Steve Eppley]

Mike O wrote:
-snip-
>It's true that with any new method, it's always best to be
>cautious, because sometimes there later turns out to be problems
>that take away the advantages. But, as I was saying, the more
>difficult a strategic vulnerability is to find & use, the less 
>of a problem it would be in actual elections.
>
>But it needn't behave like Approval except where the voter
>chose to use the method's special option.
-snip-

I don't know whether you've been confining your analysis of Iterated
Condorcet to its effect on strategy, or also looking at how it fares
on the basic criteria like GMC when voters don't misrepresent their
preferences.  And I also think we should try to find scenarios where
it elects a candidate we dislike, based on violation of some democratic
standard(s) less rigorous than criteria.

>> Would Smith// serve any purpose, though?  Wouldn't the iterations 
>> eliminate the candidates not in Smith, anyway?
>
>I can't say for sure at this time, but my intuitive impression is
>that compliance with the Smith Criterion is a separate thing,
>and would still require the use of the Smith set. But I'm not
>even sure enough about that to call it a "conjecture". These
>rankings modified during the iterations, to rank candidates equally,
>might not always change the fact that a candidate not in the Smith
>set might have the fewest voters ranking some same candidate over
>him.

My intuitive impression is that the ballots collapsing into approvals
would knock out candidates not in the Smith set, assuming *all* the
voters opted to allow their ballots to be collapsed.  But I don't
have much reason to trust my intuition on this, and the assumption 
that all voters would agree to the collapses is obviously flawed.

>I have no idea whether iterated versions of Plurality, MPV
>or Bucklin would be good, but they're worth checking out.
>But IR-1 will encounter some resistance, due to a misperception,
>even among some electoral reform organizataion leaders, that
>it violates "1-person-1-vote" in some meaningful or important
>sense.

Maybe we can knock some sense into them.  Do they also think
Approval violates one-person one-vote?  If so, why have there no
court challenges on these grounds when MostApproved has been used to
choose between rival initiatives when more than one initiative was
approved by the voters? 

---Steve     (Steve Eppley    seppley at alumni.caltech.edu)