[EM] MMV and resolvability
Markus Schulze
markus.schulze at alumni.tu-berlin.de
Sat Dec 7 21:05:30 PST 2013
Hallo,
here is another example to illustrate MMV's violation
of monotonicity.
Situation 1:
A>B, B>C, C>D, D>A, D>E, E>A each have the same
strength and are stronger than every other pairwise
defeat.
The other pairwise defeats are (sorted by their strength
in a decreasing order):
A>C
C>E
E>B
B>D
MMV skips A>B, B>C, C>D, D>A, D>E, and E>A, since they
form a directed cycle.
Then it locks A>C,C>E,E>B, and B>D, so that A is the
unique winner.
Situation 2:
Some voters rank candidate A higher (relatively to
candidate D), so that the pairwise defeat D>A becomes
weaker.
A>B, B>C, C>D, D>E, E>A each have the same
strength and are stronger than every other pairwise
defeat.
The other pairwise defeats are (sorted by their strength
in a decreasing order):
A>C
C>E
E>B
D>A
B>D
MMV skips A>B, B>C, C>D, D>E, and E>A, since they
form a directed cycle.
Then it locks A>C,C>E,E>B, and D>A, so that D is the
unique winner.
Thus, by ranking candidate A higher candidate A is changed
from a winner to a loser.
Markus Schulze
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