[EM] summary of Condorcet anti-strategy measures

[James Green-Armytage]

Dear election methods fans,
	Here is a brief list of measures that have been proposed so far with the
aim of curtailing Condorcet's vulnerability to the burying strategy. I
invite all participants to remind me of other proposals that fit in this
category, and to propose new methods with the same goal.

Iterative procedure:
	Ranked vote. Pairwise tally. Provisional completion method winner
declared. Up-down vote on provisional winner. If majority up, process is
complete. If majority down, begin again.
	Comments: This method is recommended for small groups, but unlikely to be
practical in a public election.
http://fc.antioch.edu/~james_green-armytage/voting_methods/iterative.htm

Candidate withdrawal option (CWO): 
	Ranked vote. Pairwise tally. Provisional completion method winner
declared. Non-winning candidates have the option of withdrawing from the
race and ordering a re-tally with their names deleted from the ballot.
	Comments: A simple method that is practical for public elections,
although some people tend to find it counterintuitive. It is possible that
CWO could produce a strange result in the event of a sincere cycle.
http://lists.electorama.com/pipermail/election-methods-electorama.com/2005-February/014703.html

AERLO/ATLO:
	AERLO (automatic equal ranking line option) allows a voter to specify
that all preferences between candidates ranked above a certain line should
be changed to equalities in the event of a majority rule cycle. ATLO
(automatic truncation line option) allows a voter to specify that all
preferences between candidates ranked below a certain line should be
changed to equalities in the event of a majority rule cycle.
http://en.wikipedia.org/wiki/Voting_system#Single_Winner_Variations

Strong/weak preference option (S/WPO):
	Voters can express both strong and weak preferences. The direction of
pairwise defeats are determined by both strong and weak preferences, and
the strength of pairwise defeats are determined only by strong preferences.
	Comments: Slightly more flexible variant on AERLO/ATLO.

Cardinal pairwise (aka cardinal-weighted pairwise or CWP):
	Voters rate candidates from 0-100. Separate rankings are optional
(otherwise they can be inferred from ratings). The directions of pairwise
defeats are determined by rankings information, and the strength of
pairwise defeats are determined by ratings information, according to the
procedure described in the links below:
http://fc.antioch.edu/~james_green-armytage/cwp13.pdf
http://fc.antioch.edu/~james_green-armytage/cwp13.htm
http://fc.antioch.edu/~james_green-armytage/cwp21.pdf
	Comments: I advocate this as the best single-winner method for public
elections, for two primary reasons. (1) It provides relatively strong
anti-strategic protection, without requiring the majority of voters to be
strategically sophisticated in order to defend against incursion. (2) I
claim that it provides a more meaningful resolution to sincere cycles than
strictly ordinal methods.

Approval-weighted pairwise (AWP):
	Similar to cardinal pairwise, but with a ranked ballot and an approval
cutoff rather than a continuous 0-100 cardinal scale.
http://lists.electorama.com/pipermail/election-methods-electorama.com/2004-June/013241.html
	Comments: Provides many of the benefits of cardinal pairwise, with a less
complex interface. Differs from AERLO/ATLO in that the two lines are the
same, and that voters do not have the option of omitting the line.

my best,
James Green-Armytage
http://fc.antioch.edu/~james_green-armytage/voting.htm