[EM] Woodall's criteria (a list, including methods)

[Kevin Venzke]

These are the criteria Woodall uses.  I omitted the ones (such as Clone-Loser
and Mono-Add-Plump) which all of our methods meet.

Plurality (winner's non-last rankings must >= others' first rankings)
Majority (including sets of candidates)
four Condorcet criteria (Condorcet and Smith, and a weaker form of each)
Clone-Winner
Mono-Raise (ordinary monotonicity)
Mono-Add-Top
Mono-Remove-Bottom
Participation
Mono-Raise-Delete (raise and truncate)
Mono-Sub-Plump (replace some ballots with bullet votes)
Later-no-Help
Later-no-Harm
Symmetric-Completion.

FPP is said to meet all but Majority, Condorcet, and Clone-Winner.

Approval meets all but Majority, Condorcet, Later-no-Harm, and SC.

IRV meets Plurality, Majority, Clone-Winner, Mono-Add-Top, both LNH criteria,
and SC.

Tideman(WV) is charted as meeting Plurality, Majority, two of the Condorcet
criteria (though Woodall seems to be mistaken about the failed ones), Clone-Loser,
and Mono-Raise.

Tideman(m) is the same, but fails Plurality and meets Symmetric-Completion.
Woodall has it passing all Condorcet criteria (and is no doubt correct about
that).

Approval-Elimination Runoff ("AER;" Woodall calls it "Approval AV") is the same 
as WV except it lacks the Condorcet criteria.

Descending Acquiescing Coalitions ("DAC") meets everything except for the
Condorcet criteria, Later-No-Harm, and Symmetric-Completion.

Descending Solid Coalitions ("DSC") is the same, but gains Later-No-Harm,
and loses Later-No-Help, Mono-Raise-Delete, and Mono-Sub-Plump.


In chart form, if you can view it in Courier ("X" means "yes"):

pmccmmmpmmlls
X   XXXXXXXXX fpp
X  XXXXXXXX   approval
XX X X    XXX irv
XXXXX         wv
 XXXX       X margins
XX XX         aer
XX XXXXXXXX   dac
XX XXXXX   X  dsc

I hope this information may be of interest.


Kevin Venzke
stepjak at yahoo.fr


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