[EM] MMPO vs PC addendum

[James Green-Armytage]

James responding to Mike, on the subject of MMPO's LNHarm compliance...

Mike, you wrote:
>Amazingly, MMPO gives protection at both ends, so that you don't need to 
>rank someone over your favorite, but, in the other direction, you also
>have 
>no dis-incentive to extend your ranking as low as you want to.

	I have recently discussed this with Kevin.
	I argue that voters will have an indirect but strong incentive to
truncate, in order to deter what you call "offensive order reversal". 
	Mike, you and I have agreed in previous postings that the ability to
deter by truncation may be important to the strategic stability of WV
methods. (Indeed, you have used this as a primary argument for WV over
margins.) 
	If this counterstrategy is important to the stability of WV, it will be
equally important to the stability of MMPO. Thus, I argue that
counterstrategic truncation would probably be common in MMPO. If so,
MMPO's LNHarm compliance may be an empty victory in practice.

Sincerely,
James

A relevant quote from a message that I addressed to Kevin:
>	It is not always safe for voters to rank all preferences in MMPO. As in
>WV, truncation (equal ranking) can still be useful (arguably necessary in
>some cases) as a deterrent counterstrategy.
>http://fc.antioch.edu/~james_green-armytage/vm/define.htm#counterstrat	
>	If voters fail to use this strategy, they will sometimes be inviting a
>burying strategy against their preferred candidate.
>
>Example (sincere preferences)
>46 A>B>C
>44 B>A>C
>5 C>A>B
>5 C>A>B
>	The A>B>C voters should vote A>B=C, and the B>A>C voters should vote
>B>A=C. Otherwise it is possible for a burying strategy to undermine the
>A-B comparison.
http://lists.electorama.com/pipermail/election-methods-electorama.com/2005-May/016082.html