Juho wrote (23 May 2010):
<snip>
/ 1. Rank the candidates. Truncation is allowed. Equal ranking is not
/>/ planned for (but we could come up with something).
/>/ 2. Label the candidates A, B, C, ... Z in descending order of first
/>/ preference count.
/>/ 3. Let the current leader be A.
/>/ 4. While the current leader has a majority pairwise loss to the very
/>/ next candidate, set the current leader to the latter candidate. (In
/>/ other words step 4 must be repeated until there is no loss or no other
/>/ candidates.)
/>/ 5. Elect the current leader.
/
How about this example and LNH.
6: A>C
5: B>A
2: C>B
2: C
Candidate names indicate the order in first preferences. B beats A. C
beats B. C wins.
6: A>C
5: B>A
2: C>B
2: C>A
Two "C" voters have changed their vote to "C>A". B does not beat A. A
wins. The "C" voters were harmed when they included their later
preferences.
Juho
Juho,
The key word you missed in the definition is "majority". In both your
elections there are 15 ballots, so a
"majority pairwise loss" requires a winning score of at least 8.
In both cases the FPP winner A wins, in the first because B's pairwise score
against
A is 7, a pairwise win but not a "majority" pairwise win (and so of course not a
"majority pairwise loss" for A).
Chris Benham
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