FpA-fpC
fpA-fpC (for first preference A minus first preference C) is a three-candidate Condorcet method based on first preference Copeland.[1] Its election cases are:
- If there's a Condorcet winner, then that candidate wins.
- If the Smith set is size two, then the winner is according to majority rule.
- If the Smith set is size three, then for each candidate, assume without loss of generality that the candidate is A in an A>B>C>A cycle. A's score is A's first preferences minus C's first preferences. The candidate with the highest score wins.
This method shares the strategy resistance of Smith-IRV hybrids, such as chicken dilemma compliance and dominant mutual third burial resistance; yet, unlike them, is monotone. It is open (not obvious) how to extend the method to more than three candidates in a way that retains both monotonicity and strategy resistance.[fn 1]
It produces similar results to electing the winner according to Carey's Improved First Past the Post method if there is a Condorcet cycle, and electing the Condorcet winner otherwise.
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Notes
- ↑ Any generalization will preserve its chicken dilemma compliance, as that criterion is only defined on three-candidate elections. However, this is not true of dominant mutual third burial resistance.
References
Automatically generated
The references described below are automatically pulled from the article prose above:
- ↑ Munsterhjelm, K. (2016-02-07). "Strategy-resistant monotone methods". Election-methods mailing list archives.
Manually inserted
This is a list of emails to the EM-list, originally compiled by User:Kristomun in a comment on the "Talk:" page for this article, but possibly augmented by others after February 2022:
- "Strategy-resistant monotone methods" 2016-02-07 (User:Kristomun)
- "Re: MJ -- The easiest method to 'tolerate'" 2016-09-22 (User:Kristomun)
- "Resolvable weighted positional systems all fail independence of clones" 2017-12-03 (User:Kristomun)
- "Fwd: What are some simple methods that accomplish the following conditions?" 2019-06-01 (Forest Simmons)
- "Re: Improved Copeland" 2019-06-07 (User:Kristomun, also Forest Simmons)
- "Unmanipulable majority and Condorcet" 2020-01-03 (User:Kristomun, also Forest Simmons)
- "Minimally manipulable methods: preliminary results" 2020-11-02 (User:Kristomun; first post about the MIP minimally manipulable method search)
- "Re: A Metric for Issue/Candidate Space" 2020-12-23 (Kevin Venzke)
- "Re: Best Ranked Preference Deterministic Method?" 2020-12-24 (User:Kristomun, KV, FS)
- "Re: extending fpA-fpC" 2020-12-26 (Kevin Venzke)
- "Re: Agenda Based Banks" 2021-08-04 (Forest Simmons)
- "Re: Defeat Strength Demystified" 2021-09-17 (Forest Simmons)
- "Re: 'Independence of cycles' and a possible new method" 2021-12-12 (User:Kristomun, Toby Pereira, Colin Champion, Forest Simmons)
- "Re: Quick and Clean Burial Resistant Smith, compromise" 2022-01-09 (User:Kristomun, Kevin Venzke, Daniel Carrera, Forest Simmons)