[EM] ER-Bucklin fails monotonicity

Kevin Venzke stepjak at yahoo.fr
Wed Jun 29 08:06:48 PDT 2005


By the way, I didn't specify ER-Bucklin(whole) because I didn't believe that
ERB(fractional) had been defined.

--- James Green-Armytage <jarmyta at antioch-college.edu> a écrit :
> Yes, this is interesting. However, I suggest that ER-Bucklin(whole) should
> perhaps be tallied in a different way. In the second example, you assume
> for tally purposes that D is in 2nd place on the A=B>D ballots. However, I
> suggest that we should still consider D to be in 3rd place, because there
> are still two candidates who are ranked strictly ahead of D. If we do
> this, I think that B still wins. 
> Here's another example: a ballot marked A>B=C=D>E>F=G=H=I>J. I think that
> we should consider A to be in 1st place, B, C, and D to be in 2nd place, E
> to be in 5th place, F, G, H, and I to be in 6th place, and J to be in 10th
> place. Thus, the ballot would not count in favor of E until the 5th round,
> and it would not count in favor of J until the 10th round.
> If we use this method, does ER-Bucklin pass monotonicity again? If so, I
> suggest that it is probably better than the version of ER-Bucklin(whole)
> that you used in your example.

This seems like a new interpretation. I believe both this interpretation and
ERB(fractional) satisfy monotonicity, since in neither method can raising
a candidate cause any other candidate to get their votes earlier.

Kevin Venzke


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