[EM] Re: auto-truncation

[Araucaria Araucana]

On 26 Apr 2005 at 13:43 UTC-0700, Kevin Venzke wrote:
>H> i,
>
>  --- Araucaria Araucana <araucaria.araucana at gmail.com> a écrit : 
>> >> Consider this case.  Original true preferences:
>> >>   27: A>B
>> >>   24: B>A
>> >>   49: C
>> >> A is the Condorcet winner.  Now consider what happens if B defects
>> >> via truncation:
>> >>   27: A>B
>> >>   24: B
>> >>   49: C
>> >> Under RP(wv), Beatpath(wv) or DMC, B wins.  B voters have gotten a
>> >> better result by dropping a lower preference.  This is an example of
>> >> the "Later No Hurt" violation of Condorcet completion methods -- B
>> >> voters hurt their favorite by adding a lower-ranked preference.
>> >> But if A puts the approval cutoff above B, B can't win in DMC:
>> >>   27: A>>B
>> >>   24: B
>> >>   49: C
>> >> C wins, anyway you cut it, as you found.  There's no LNHurt
>> >> situation
>> >> here because B can't win either way.  So the best the B voters can do
>> >> is to add a preference for A.  That's what I mean by the poison pill
>> >> (by the A voters).  Is it clear now?
>
> I have an even better idea that doesn't require an approval cutoff:
>
> If there is no CW, elect the Borda loser.
>
> (Somewhat less arbitrary, more clearly punishment.)
>
> Kevin Venzke

I didn't see a smiley, but I assume one was implied.

-- 
araucaria dot araucana at gmail dot com