[EM] Re: auto-truncation

[Kevin Venzke]

Hi,

 --- 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



	

	
		
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