[EM] Hybrid Beats-All/Approval v. Straight Approval

Forest Simmons fsimmons at pcc.edu
Mon Oct 29 21:50:32 PST 2001

On Mon, 29 Oct 2001, Bart Ingles wrote:

> Forest Simmons wrote:
> > 
> > If voter X is almost sure that his ballot will make the difference between
> > a hated (by X) Condorcet Winner and a Condorcet tie (to be settled by
> > chance), voter X might be tempted to deliver up the election to chance
> > even if that required him to vote his favorite last and his most despised
> > first.
> > 
> > Of course, if all like minded voters gave in to the same temptation, the
> > tie breaker odds of favorite to most despised would be adversely affected.
> But if the aim is to sabotage the Condorcet candidate, the insincere
> voters would be more likely to manipulate lower preferences, leaving the
> first choice intact.  So the random tie breaker would be unaffected (I
> think).
> If the strategic aim is to help the Condorcet candidate using insincere
> strategy, and the voters rank the likely Condorcet candidate equal or
> higher than their sincere favorite, then this would of course affect the
> random tiebreaker.  This may not be a concern, though, since the
> motivation in this case is to prevent the tiebreaker from being used in
> the first place.

You're probably right. But all it would take is one simple example to lay
all of the doubts to rest.

I'll add that to my growing list of projects if nobody else comes up with
a concrete example soon. 

Meanwhile, I'm more interested in the main question.  Is there a method
which is as non-manipulable as random ballot which satisfies the Condorcet

In particular is either Cranor's method or Iterated Instant Approval
Runoff (from high resolution CR ballots) in that category? 


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