[EM] James Armytage's article on Condorcet-IRV hybrids

[Michael Ossipoff]

I don't know when, but James Green-Armytage wrote an interesting article on
hybrids between IRV and Condorcet.

It's at:

http://econ.ucsb.edu/~armytage/hybrids.pdf

I mention it because it says (among other things) basically what I've been
saying:

James says that IRV is remarkably strategy-free. I'd say that, more than
that, IRV is entirely strategy-free if you're in a mutual majority (MM).

Admittedly, you should oppose IRV if you aren't in a mutual majority (Hear
that, Democrats and Republicans?). But there's nothing undemocratic or
unfair about government by a cohesive majority. So I suggest that IRV's
favorite-burial incentive for non-MM voters is unimportant in comparison to
its strategy-freeness for MM voters.   ...for Green scenario conditions.
Under current conditions, FBC failure for anyone is unacceptable, because
it's so easy for the media to lead people to believe that they're the
voters who need to favorite-bury.

James also points out that the Condorcet-IRV hybrids further improve
strategy-free-ness. Correct again. The hybrids get rid of the instability
that results from IRV's sometime elimination of CWs, thereby getting rid of
the big, obvious and relatively-frequent favorite-burial need for non-MM
voters. And thereby getting rid of the vulnerability to Burlington-like
rejection.

(If the CW-preferrers primarily want to elect their CW, and the CW gets
eliminated, then they'll be dis-satisfied. The non-MM voters will likewise
be dis-satisfied. That adds up to a dis-satisfied majority, who might throw
IRV out, as in Burlington. The Condorcet-IRV hybrids avoid that, by
electing CWs.)

James discusses 4 hybrids, which he refers to as:

Woodall
Benham
Smith//AV
Tideman

("AV" is a term for "IRV")

He points out that they all meet the Smith criterion, and therefore meet
the Mutual Majority Criterion (MMC), among others.

He says that Woodall and Benham meet Mono-Add-Plump and Mono-Append, but
not Smith IIAC.

...and that Smith//AV and Tideman meet Smith IIAC, but no Mono-Add-Plump
and Mono-Append.

I wanted to mention this article, because I agree that (under Green
scenario conditions) those 4 hybrids, and maybe others too, are, in
important respects, the best voting systems. They'd be my favorites,
for Green scenario conditions.

...provided that safeguards are in use to ensure a fraud-free count. We've
discussed how that's possible, if the various parties have the opportunity
to image the paper ballots simultaneously, as each is shown.   (...paper
ballots printed out from voting machines, and examined by voters before
being deposited in a ballot-box)

Though the article defines the hybrids, the definitions are all brief, and
so I might as well state them here:

Woodall:

Do IRV until only one member of the initial Smith set remains. Elect hir.

In other words, repeatedly cross off from the rankings the candidate who
currently tops fewest rankings.

...until only one member of the initial Smith set remains un-crossed-off.
Elect hir.

[end of Woodall definition]

Benham:

Do IRV until there's a CW among the uneliminated candidates, looking only
at defeats among them. Elect that CW.

[end of Benham definition]

Smith//AV:

Do IRV among the members of the initial Smith set.

[end of Smith/AV definition]

Tideman:

Alternately eliminate the nonmembers of the current Smith set, and the
as-yet uneliminated candidate who is the uneliminated candidate highest
on fewest ballots. Elect the last uneliminated candidate.

[end of Tideman definition]

Michael Ossipoff
-------------- next part --------------
An HTML attachment was scrubbed...
URL: <http://lists.electorama.com/pipermail/election-methods-electorama.com/attachments/20130217/943efcc5/attachment.htm>