Talk:VoteFair Ranking

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Merge with Kemeny-Young Maximum Likelihood Method

Is this the same method as Kemeny-Young Maximum Likelihood Method. -- RobLa (talk) 08:14, 16 August 2020 (UTC)

No! They are NOT the same.

What IS needed is to edit the page Kemeny-Young Maximum Likelihood Method to point out that it has two other names, namely Condorcet-Kemeny and VoteFair popularity ranking.

In other words, the word "popularity" is a very important qualifier. It distinguishes between VoteFair ranking and VoteFair popularity ranking.

For reference, the Wikipedia page named Kemeny-Young method has the correct info. However that title was chosen by Markus Shulze who dislikes the Kemeny method because it so closely competes with "his" method, so he made a point not to include the word Condorcet, and instead included the less-important name "Young". VoteFair (talk) 20:16, 17 August 2020 (UTC)

What I'm proposing is that instead of two articles (Kemeny-Young Maximum Likelihood Method and VoteFair Ranking) we have one article with the important information from both of the current articles. Based on my limited understanding (mostly from our limited discussions elsewhere), the merged article should probably be called "Condorcet-Kemeny", but I'm inclined to get other opinions on the topic. The merged article should explain the variations (which can include "VoteFair popularity ranking"). I'm not in a huge rush to make the change, but I am eager to make electowiki into a more useful reference site. -- RobLa (talk) 20:45, 17 August 2020 (UTC)

FWIW, this is what I've gathered from investigation, EM posts etc.

- VoteFair ranking methods are a set of methods, each for a different purpose (e.g. single-winner, PR, aiding negotiations).

- The VoteFair popularity ranking is mathematically defined in such a way as to always agree with Kemeny-Young when the latter is unambiguous (no ties). The only difference is, IIRC, the VoteFair popularity ranking maximizes the sum of pairwise magnitudes agreeing with the final ranking, and Kemeny-Young minimizes the sum of pairwise magnitudes disagreeing with the final ranking.

- The VoteFair reference implementation does not implement the popularity ranking: it takes shortcuts that makes the result diverge from optimum in certain cases with very large Smith sets. In exchange, the implementation is always polytime, whereas calculating the Kemeny winner is NP-hard.

As for the name of the method itself, Kemeny-Young seems okay to me. It attributes credit to both Kemeny and Young, and distinguishes the method from the "other" Young method (where the winner is the candidate who becomes the CW after deleting the fewest ballots). It doesn't include the name "Condorcet", true, but neither does, say, River or Ranked Pairs. Kristomun (talk) 07:54, 18 August 2020 (UTC)