Difference between revisions of "MMPO,FPP"

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(Created page with "MMPO,FPP refers to MinMax (Pairwise Opposition) breaking ties in best score by electing the candidate with the most first preferences (on the unmodified original b...")
 
 
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It's not possible for a sensible method to elect C anymore.
 
It's not possible for a sensible method to elect C anymore.
  
[[Category:Single-winner voting systems]]
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[[Category:Single-winner voting methods]]

Latest revision as of 07:29, 11 May 2017

MMPO,FPP refers to MinMax (Pairwise Opposition) breaking ties in best score by electing the candidate with the most first preferences (on the unmodified original ballots).

Since MMPO returns ties relatively often, a tiebreaker is needed. FPP is the most obvious one, and also doesn't differ much from other tiebreakers. The comma notation in "MMPO,FPP" signifies that one doesn't eliminate the MMPO non-winning candidates before counting first preferences.

Like all MMPO tiebreakers that preserve Later-no-harm compliance, the combined method violates the Plurality criterion:

49 A
27 B>C
24 C
100

MMPO,FPP breaks the MMPO tie between B and C by electing B, who is not allowed to win according to Plurality.

It can easily be shown that electing C instead would result in a Later-no-harm violation, because if the C voters add preferences for B:

49 A
27 B>C
24 C>B
100

It's not possible for a sensible method to elect C anymore.