[EM] MMPO has incentive for reversa l, but not compromise-reversal.
nkklrp at hotmail.com
Fri Jun 10 22:42:10 PDT 2005
* pro MMPO: 1. LNHarm, 2. zero compromising-reversal incentive
I replied (in part):
his renaming is incorrect.
I wasn't trying to rename your criterion.
No, you're just calling it by a different name :-)
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.
Then you just go ahead and do that, but understand that, when you talk about
compromise-reversal incentive, you're talking about favorite-burial, and
you're not talking about something that has anything to do with FBC.
"Compromise reversal incentive" is not another way of saying
"favorite-burial", and doesn't refer to what FBC is about.
As I pointed out before (apparently with no effect), "compromiise-reversal"
can be rewarded in MMPO. What isn't rewarded in MMPO is voting someone over
your favorite. So I'll tell you again what I told you yesterday:
compromise-reversal does not mean the same as "favorite-burial". But of
course you can talk about what you want. But when you talk about something
that I didn't talk about, then that can't be called a reply.
But of course no one says that you have to consider FBC important. Maybe it
doesn't matter to you if voters have strategic need to bury their favorite.
If not then of course no one has any reason to expect you to talk about FBC.
By the way, if you know of a method in which no one can ever benefit from
"compromise-reversal", one would hope that you would tell us about it.
In Approval it's possible to benefit from order-reversal that doesn't
involve one's favorite. It isn't likely, and it's been argued that its
likelilhood is low enough that it should be ignored. But in principle the
order-reversal benefit is there in Approval (and therefore in CR). And, as I
said, in MMPO.
Although the two concepts
are similar, they are not intended to be identical. I made this clear when
I first proposed the terminology.
Well, there are methods in which no one can benefit from favorite-burial,
but there aren't methods in which, even in principle, no one can benefit
I'd said (in two different parts of my posting):
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?
Sure: Say the method is MMPO, and you reverse your 2nd and 3rd choices,
voting your 3rd choice in 2nd place, and your 2nd choice in 3rd place.
Doing that can't benefit your 3rd choice, because ranking him/her equal to
your 2nd choice would have been enough to remove from him/her one
vote-against. But doing that _can_ keep your 2nd choice from beating your
Say that your 3rd choice is the candidate ranked over your 2nd choice by the
most voters. By voting your 3rd choice over your 2nd choice, you're adding
one vote-against to your 2nd choice's MMPO score. If you and one other
person do that, you could change the winner from your 2nd choice to your 1st
choice, if your 1st choice would have been the close runner-up, only one
point behind, had you not done that order-reversal.
Compromising strategy: Insincerely ranking an option higher in order to
decrease the probability that a less-preferred option will win.
No objection to that definition, which is clear enough. I just refer instead
to order-reversal, truncation, and equal ranking, where the order-reversal
and equal-ranking could, but needn't, be compromise as you define it. I say
it that way because, if it's compromise, it makes all the difference which
kind of compromise it is. I talk about different distinctions than you do.
And if it's done to protect the win of a CW, or to protect majority rule,
then I call it defensive. It's just a question of what someone wants to
express or emphasize, what distinctions they want to express. As I said,
they used to say that the Eskimos had a thousand words to distinguish
between different kinds of snow. Though it wasn't true, it demonstrates the
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?
If you're raising D above F, where D would sincerely be below F, that adds
to the number of people ranking D over F. If D is the candidate ranked over
F by the most people, then, by so doing, you've increased F's
unpreferredness score. If someone you like better than F was only one point
worse than F, and if you and one other person both add to F's
unpreferredness score, then you change the winner to someone you like
better, and are rewarded by the order-reversal.
But that isn't compromse, as you define it, because you aren't doing it to
make D win. You like D less than F, so you wouldn't want to change the
winner from F to D.
It's reversal, but it isn't compromise-reversal.
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?
It wouldn't be better for that purpose.
If you want to keep U from winning, why would you raise him/her in your
ranking? What you're doing in your example is lowering, or "burying" S. That
can stop S from winning in MMPO.
case, I am removing an opposition vote against T
, while maintaining my
opposition vote against U.
Not so. When you change to RTUS, you're no longer ranking S over U, and so
you could be making U win, if you're lowering his worst votes-against. If
only you do that, you could make a tie that U wins. If you and another voter
do that same reversal, you could change U from loser to winner.
I don't see how adding an opposition vote
against S will help my cause.
It will help you if, by adding a vote against S, you (and one other voter
doing the same thing) can make R win instead of S, where previously S was
the winner and R was the close runner-up. Changing from the sincere RSTU to
the insincere RTUS can accomplish that for you.
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
It wouldn't. You're not changing your pairwise votes against F, in either
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.
You would do ranking #2 if you wanted to help D. You would do ranking #3 if
you wanted to help D, B, & C.
Obviously helping D, B, or C could make A lose. So MMPO doesn't completely
protect your favorite from your strategy, but at least you don't vote
someone over your favorite.
Likewise in Approval or CR, helping lower choices could make your favorite
lose, though you don't vote them over your favorite.
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?
No _likely_ reason that I know of. If you want to help D win, you should
also want to help A and B. So your 3rd ranking is better than your 2nd one.
But that's just my first impression. If, improbably, you knew that if D
could win, it would be with an electorate that wouldn't make A winnable; but
that if B or C could win, it would be with an electorate in which A would be
winnable, then your 2nd ranking could be better than your 3rd one. That
answers the question quoted above. But that kind of specific detailed
knowledge about combinations of winnability doesn't sound at all likely, and
so I'd say that, in practice, there would be no reason to vote your 2nd
ranking instead of your 3rd one.
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
Yes, that sounds right. If I earlier said that MMPO can have
compromising-reversal incentive, then I should have just said that MMPO can
have reversal incentive. MMPO can have burying reversal incentive, as you
define "burying": lowering someone in order to keep him/her from winning.
("him/her" may seem awkward, but the unacceptable candidates aren't all
Of course, as I use the term "burying", it just means voting someone lower.
So I don't add anything to the ordinary meaning of "bury".
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