Condorcet Truncation Example

[Rob Lanphier]

On Tue, 6 May 1997, Hugh Tobin wrote:
> Markus Schulze wrote:
> > But the way you have defined "truncation resistant" and
> > Smith//Condorcet [EM], the following problems will occur:
....
> > (2)Distributing the worst preferences random among the least
> >    favoured candidates becomes a usefull strategy. That means:
> >    If the voter doesn't care, who of his least favoured
> >    candidates wins [if one of them should win], then it is
> >    nevertheless the best strategy to give them different
> >    preferences to maximize the chances of a favoured
> >    candidate to win.
> 
> You are right.  I have objected to the [EM] tiebreaker on this ground. 
> Other tiebreakers, such a margins-of-defeat, do not create an incentive
> to vote randomly, though (at least in theory) a voter who anticipates a
> circular tie and thinks he knows who will win the pairwise race between
> his less favored candidates may cast an insincere vote to make the
> margin larger.  

I think that the tendency to vote randomly for the bottom candidates is a
small price to pay for the added truncation resistance.  Furthermore, if
it pays to vote randomly, it pays even more to study the differences among
the candidates who one would otherwise scatter random votes upon and
determine how best to rank them sincerely.

This does bring up an interesting point, though, which is that
Smith//Condorcet[EM] seems to encourage voters to be less differentiating
of their favorite candidates, and then get more and more particular of
candidates as one moves down the list.  At the bottom of the list, one is
encouraged to find the most minute differences and rank otherwise
identical candidates differently. 
---
Rob Lanphier
robla at eskimo.com
http://www.eskimo.com/~robla