[EM] Re: Burying and defection with the "defeat-droppers".

[James Green-Armytage]

>As far as I can tell from your website, with some
>beating about the bush, yes. If pressed as to which
>you think is the best plain ranked-ballot method for
>public political elections, I gather you reccomend
>using Winning Votes with either  Beat Path, Ranked
>Pairs or River.

	Yeah, so far that's what it looks like to me... I'm just not sure if I
really like any plain ranked methods...

>You say your Cardinal-Weighted Pairwise method is only
>"marginally preferable to Condorcet methods which only
>use ranking information".

	Yeah, okay, I changed that.

>In my opinion DD(WV)'s vulnerability to this type of 
>burial/defection sits very badly with its 0-info.
>random-fill incentive.

	Please don't worry about 0-info strategy. The 0-info case is unrealistic.
>
>"Weak Defection Resistance: If  winning candidate x is
>the CW and the FPW, and xy are a solid coalition with
>more than 2/3 of the votes; and afterwards  some
>ballots that rank y above x and z are changed so that
>z's ranking relative to x is raised while keeping y
>ranked above both; then if there is a new winner it
>cannot be y."

	I'm not sure that this will be useful... the if's just seem too large...
>
>"Weak Burial Resistance: If winning candidate x is the
>CW and FPW while z is the CL and FPL , and afterwards 
>some ballots that rank any y above x and z are changed
>so that 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."

	Again, I suspect that the if's are too large. We should be able to
protect CW's whether they are the plurality winner or not.
	I recently made a list of methods that I think are more burial-resistant
than DD(WV). If I was trying to define anti-strategy criteria for
Condorcet methods, I'd try to find good properties that these methods have
that other pairwise methods don't. It's hard to put it into criteria,
though, because it has so much to do with voter behavior.
>
>"CNTT,AV" (Smith,IRV) is in my view a good method that
>meets it.

	I'm not sure that Smith/IRV is a great method. Basically, whenever the
IRV winner differs from the CW, supporters of the IRV winner have carte
blanche to bury the CW and claim the election for their guy.
>
>Unfortunately, Raynaud(GL) fails this criterion.

	I'm still waiting for you to convince me that Raynaud is more strategy
proof than defeat dropping methods. 
	Assume that the three sincere defeats are A>B A>C and B>C. 
	In Raynaud, supporters of B need to make a fake C>A defeat which is the
strongest of the three. (If order of defeat strengths is CA > AB?BC... B
wins.)
	In defeat dropping, supporters of B need to make a fake C>A defeat so
that the A>B defeat is the weakest of the three. (If order of defeat
strengths is CA?BC > AB ... B wins.)
	So, which of these strategies is usually harder to pull off? Depends on
the situation, right? In my little 46-44-10 example, then the Raynaud
strategy would be much harder, because the one and only possible "C"
candidate does so poorly in sincere pairwise comparisons. However, I'd
expect that in most serious multicandidate scenarios there would be at
least one available "C" candidate such that B voters could make a fake C>A
defeat that was bigger than the other two... And I'm starting to imagine
the messy complications... No, I'm guessing that using Raynaud won't help
too much on the strategy front...

	So, if you accept my arguments against Smith/IRV and Raynaud, and you
don't trust DD(WV), why not subscribe to one of the anti-strategy methods?
http://fc.antioch.edu/~james_green-armytage/voting_methods/antistratsum.htm

my best,
James