Majority Approval, Minimum Pairwise Opposition: Difference between revisions
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'''Majority Approval, Minimum Pairwise Opposition''' or '''MAMPO''' is one method devised by Kevin Venzke for the purpose of showing that the [[Favorite Betrayal criterion]], the [[Strong Defensive Strategy criterion]], and the [[Strategy-Free criterion]] are mutually compatible. |
'''Majority Approval, Minimum Pairwise Opposition''' or '''MAMPO''' is one method devised by [[Kevin Venzke]] for the purpose of showing that the [[Favorite Betrayal criterion]], the [[Strong Defensive Strategy criterion]], and the [[Strategy-Free criterion]] are mutually compatible. |
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Another method with these properties is [[Majority Defeat Disqualification Approval]]. |
Another method with these properties is [[Majority Defeat Disqualification Approval]]. |
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The ''score'' for candidate ''X'' against candidate ''Y'' is equal to the number of voters ranking ''X'' above ''Y''. The ''max score'' of candidate ''X'' is the largest score of any other candidate against ''X''. |
The ''score'' for candidate ''X'' against candidate ''Y'' is equal to the number of voters ranking ''X'' above ''Y''. The ''max score'' of candidate ''X'' is the largest score of any other candidate against ''X''. |
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If |
If nobody is approved by more than half of the voters, then the candidate approved by the most voters is elected. |
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Otherwise, the candidate with the lowest max score, who is approved by more than half of the voters, is elected. |
Otherwise, the candidate with the lowest max score, who is approved by more than half of the voters, is elected. |
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It fails [[Strategic nomination|Clone-Winner]], the [[Generalized Strategy-Free criterion]], the [[Condorcet criterion]], the [[Smith set|Smith criterion]], [[Participation criterion|Participation]], the [[Majority criterion|Majority criterion for solid coalitions]], and [[Later-no-harm criterion|Later-no-harm]]. |
It fails [[Strategic nomination|Clone-Winner]], the [[Generalized Strategy-Free criterion]], the [[Condorcet criterion]], the [[Smith set|Smith criterion]], [[Participation criterion|Participation]], the [[Majority criterion|Majority criterion for solid coalitions]], and [[Later-no-harm criterion|Later-no-harm]]. |
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[[Category:Single-winner voting |
[[Category:Single-winner voting methods]] |
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[[Category:Monotonic electoral systems]] |
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[[Category:No-favorite-betrayal electoral systems]] |
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Latest revision as of 11:09, 22 July 2022
Majority Approval, Minimum Pairwise Opposition or MAMPO is one method devised by Kevin Venzke for the purpose of showing that the Favorite Betrayal criterion, the Strong Defensive Strategy criterion, and the Strategy-Free criterion are mutually compatible.
Another method with these properties is Majority Defeat Disqualification Approval.
Procedure
The voter submits a ranking of the candidates. The candidates explicitly ranked are considered approved by that voter.
The score for candidate X against candidate Y is equal to the number of voters ranking X above Y. The max score of candidate X is the largest score of any other candidate against X.
If nobody is approved by more than half of the voters, then the candidate approved by the most voters is elected.
Otherwise, the candidate with the lowest max score, who is approved by more than half of the voters, is elected.
Criteria
MAMPO satisfies the Favorite Betrayal criterion, Strategy-Free criterion, the Strong Defensive Strategy criterion (and Minimal Defense criterion), monotonicity, and the Plurality criterion.
It fails Clone-Winner, the Generalized Strategy-Free criterion, the Condorcet criterion, the Smith criterion, Participation, the Majority criterion for solid coalitions, and Later-no-harm.