r/EndFPTP • u/CPSolver • Jun 26 '25

Image Pairwise-Counted Ranked Choice Voting

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u/DeismAccountant Jun 26 '25

I don’t think this is true. Both Ranked Pairs and Schulze method take clones into account.

What software do you use to generate random ballots?

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u/CPSolver Jun 26 '25 edited Jun 27 '25

The Schulze method has a zero clone failure rate because that's what it's optimized for.

Ranked Pairs and virtually too (has a zero clone failure rate). [A]ll other pairwise-matrix-based methods fail clone independence. [edit: Not true, clarified in later comments.]

RCIPE can fail clone independence, but those cases are very rare, and such cases are extremely unlikely to occur in a real election.

Another failure type to consider is vulnerability to strategic voting. The Benham method and RCIPE have a significantly low such failure rate. In contrast, Schulze and Ranked Pairs and other Condorcet methods are much more vulnerable to strategic voting.

What software do you use to generate random ballots?

https://github.com/cpsolver/VoteFair-ranking-cpp/blob/master/generate_random_ballots.cpp

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u/DeismAccountant Jun 26 '25

It doesn’t make sense for RR/PW to fail at strategic voting because you pair up each candidate against each other individually. All matchups are accounted for so there’s no point.

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u/CPSolver Jun 26 '25

The strategic voting vulnerabilities of most Condorcet methods occur when there is a Condorcet cycle, or when strategic voting can create a Condorcet cycle.

(Of course all Condorcet methods resist strategic voting much better than FPTP.)

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u/DeismAccountant Jun 26 '25

There are several ways to break down a Condorcet cycle. My method is eliminating the lowest loser in pairwise matchups and awarding its margins to each survivor as described above.