[EM] Defeat strength, Winning Votes vs. Margins, what to do with equally-ranks on ballot?

Chris Benham cbenhamau at yahoo.com.au
Wed May 22 14:35:37 PDT 2019


Another Condorcet-compliant method that might interest you, from a Kevin 
Venzke webpage:

> *Jobst Heitzig's River method* is identical to Tideman's method, 
> except that one additionally ignores (without locking) defeats against 
> candidates against whom some defeat has already been locked. This is 
> possibly the easiest of the three to work out by hand.
The other two he is referring to are Schulze and Tideman RP. Nearly all 
the time it will elect the same candidate and as far as I know is at 
least as good.

I strongly suggest that the measure of defeat strength should be Losing 
Votes and that ballots that equal-rank A and B above bottom should 
contribute a whole vote
to each in the A-B pairwise comparison. Ballots that rank A and B 
equal-bottom (or truncate both A and B) should contribute nothing to the 
A-B pairwise comparison.

I'll be posting more on this soonish, but since you asked the question I 
thought I'd just give you some food for thought to be going along with.

Chris Benham

On 21/05/2019 6:36 am, robert bristow-johnson wrote:
> So this would be about Tideman Ranked-Pairs, or Schulze, or some other 
> Condorcet-compliant method.
> It doesn't make much difference if the measure of Defeat Strength is 
> Margins (supporting votes minus opposing votes), but what if Winning 
> Votes is the measure of Defeat Strength in either RP or Schulze??? How 
> should a pair of candidates that are equally-ranked on a ballot be 
> counted??? Do you count it (as a winning vote) for *both* candidates??? 
> For neither candidate? (I dislike the idea of a half-vote for both 
> candidates.?? And I hate the idea of not allowing equal-ranking in a 
> Condorcet RCV election.)
> What is the right way to do this??? It seems the most consistent might 
> be to count an equally-ranked votes for **neither** candidate, since 
> we consider unranked candidates as tied for last place on the ballot, 
> and we would count those as votes.
> But what do you guys think??? If we allow for equal-ranking in a 
> Condorcet-compliant RCV, how do we deal with it in terms of vote totals?
> --
> r b-j?? ?? ?? ?? ?? ?? ?? ?? ?? ?? ?? ?? ??rbj at audioimagination.com
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