Mike Ossipoff wrote (6 Nov 2011):
FBC is essential for public elections.
My current favorite is MDD, ER-Bucklin (whole) (where
ER-Bucklin(whole) is defined
as in the electowicki).
It's the Cadillac of FBC methods.
Some years ago I also liked this.
Is there an FBC-complying method meets UP and SDSC and that does
better by other criteria?
Yes. IBIFA does.
http://lists.electorama.com/htdig.cgi/election-methods-electorama.com/2010-June/026572.html
25: A>B
26: B>C
23: C>A
03: C
(77 ballots) B>C 51-26, C>A 52-25, A>B 48-26
All candidates have a majority-strength pairwise defeat, so MDD
disqualifies no-one. No candidate
is top-rated on more than half the ballots, so MDD,ER-Bucklin(whole)
elects the most approved
candidate C.
Now say we add 23 ballots on which C is top-rated and all the other
candidates are ignored.
25: A>B
26: B>C
23: C>A
26: C
(100 ballots) B>C 51-49, C>A 75-25, A>B 48-26
Now B alone is without a majority-strength pairwise defeat, so MDD
disqualifies A and C (and B wins).
This is a failure of the Mono-add-Plump criterion, which is met by
IBIFA and SMD,TR and plain
ER-Bucklin(whole) and MCA and any method that I find acceptable.
Is there an FBC-complying method that doesn't fail in the Approval
bad-example?
Maybe MDD,TR fills that bill, but it like MDDA also fails mono-add-plump.
Chris Benham
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