[EM] Re: Condorcet package-wvx

[Kevin Venzke]

Daniel,

 --- Daniel Bishop <dbishop at neo.tamu.edu> a écrit : 
> Don't you mean half a vote for each candidate over every other?  Of 
> course, if you're using margins, it doesn't make any difference.
> 
> At least for single-winner Condorcet elections, I don't think it's 
> necessary to explicitly count X=Y as (0.5 X>Y + 0.5 Y>X) as long as they 
> are equivalent in the sense of
> 
> * Pairwise Cancellation Criterion: If there is one ballot that ranks 
> X>Y, and another ballot that ranks Y>X, and both of these ballots are 
> changed to rank X=Y without affecting the relative ordering of any pair 
> of candidates other than {X, Y}, then the winner must not change.

Margins seems to satisfy this, but WV wouldn't. In particular, this could
cause the loser of the X-Y contest to be elected instead of a third candidate.

> It might also be a good idea to require:
> 
> * Neutrality of Equal Rankings: The addition of one or more ballots that 
> rank X=Y will never change the winner from X to Y or vice-versa.

This criterion seems extremely strong. There could be other candidates
ranked on those ballots.

Kevin Venzke



	

	
		
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