[EM] " Weak Burial Resistance" criterion

[Chris Benham]

James,
I've given some more thought  to coming up with a
criterion that distinguishes methods that use IRV as
the most decisive stage (like Woodall's CNTT,AV aka
Smith,IRV and  CDTT,IRV), as being more resistant to 
Burying than Condorcet  methods like the
defeat-droppers, Raynaud (all versions) and SCRIRVE.

"If  x is the CW (and wins), and on more than 1/3 of
the ballots ranked  above y and z; and afterwards on
some of the ballots that rank y above x and x not
below z, z's ranking relative to x is raised while
keeping y ranked above them both, then if there is a
new winner it cannot be y."

This could be called  the "Weak Burial Resistance"
criterion, and of course is highly reminiscent  of 
your excellent in-defence-of-IRV  "Dominant Mutual
Third" criterion.

On Sun.Apr.10, you wrote a similar idea:

"In IRV, if candidate X is the sincere Condorcet
winner, and more than 1/3 of the voters rank X in
first place, then I think that no strategic
manipulation will be possible, in that no set of
voters can gain mutual advantage by changing the
winner to someone else. (You can probably generalize
this from one candidate to a set of candidates, which
I earlier defined as a "dominant mutual third" set.) 
I don't think that many pairwise methods share this
property. So that would be a new problem,right? 
A sincere Condorcet winner with more than 1/3 of the
first choice vote would no longer be totally safe from
strategic manipulation."


Chris  Benham

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