[EM] Mike: does MM(po) have compromising-reversal incentive??

[James Green-Armytage]

James replying to Mike, on the subject of compromising-reversal incentive
in MM(po)...

James:
>* pro MMPO: 1. LNHarm, 2. zero compromising-reversal incentive
Mike:
>his renaming is incorrect. 

	I wasn't trying to rename your criterion. You're welcome to talk about
FBC. But when I compare methods, I prefer not to talk about FBC, but
rather about compromising-reversal incentive. Although the two concepts
are similar, they are not intended to be identical. I made this clear when
I first proposed the terminology.
http://lists.electorama.com/pipermail/election-methods-electorama.com/2004-March/012515.html

>What could be called "compromising 
>reversal" can profit you in MMPO, if the candidate ovewr whom you raise
>your 
>compromise isn't your favorite. 
...
>Compromising reversal can profit a voter in MMPO, when 
>the candidate over whom the compromise is raised isn't one's favorite.

	That's interesting. Are you sure that there is compromising-reversal
incentive in MMPO? I can't see how. Can you give an example where
compromising-reversal is more effective than compromising-compression? 

Definitions:
Compromising strategy:  Insincerely ranking an option higher in order to
decrease the probability that a less-preferred option will win. 
Compromising-reversal: A compromising strategy that involves insincerely
reversing the order of two candidates on the ballot. 

	For example, if my sincere preferences are B>D>F, a compromising-reversal
strategy would be to vote D>B>F in order to decrease F’s chances of
winning. This also applies if I rank other candidates above, below, or in
between B, D and F, e.g. changing A>B>C>D>E>F>G to A>D>B>C>E>F>G in order
to decrease F's chances of winning.
	If I am raising D on the ballot to decrease the chance that F will win,
in MMPO, how could order-reversal help this cause in a way that equal
ranking could not?

Example 1: sincere preferences R>S>T>U. Why could R>T>U>S be better than
R>S=T>U in terms of decreasing the chances that U will win? In either
case, I am removing an opposition vote against T, while maintaining my
opposition vote against U. I don't see how adding an opposition vote
against S will help my cause.

Example 2: sincere preferences A>B>C>D>E>F>G. Why could A=D>B>C>E>F>G be
better than A=B=C=D>E>F>G in terms of decreasing the chances that F will
win? In either case, I am removing my opposition votes against D, while
maintaining my opposition votes against F.
	It's true that the second strategy allows me to keep some opposition
votes against B and C. But if I'm willing to compromise by removing
opposition to D, with the intent of electing D, why would I be unwilling
to remove opposition to candidate whom I like better than D?

	It seems to me that for any possible compromising-reversal strategy in
MMPO, there is a compromising-compression strategy that is just as
effective. Hence, it seems that MMPO has no compromising-reversal
incentive.
	
>
James:
>slightly less vulnerable to burying-compression strategies
Mike:
>
>Translation: Truncation (?)

	Burying strategies that use truncation or equal ranking. These
definitions are on my web site and on electowiki.
http://fc.antioch.edu/~james_green-armytage/vm/define.htm#strategy
http://wiki.electorama.com/wiki/Tactical_voting

Sincerely,
James
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