[EM] m vs wv reply continued

[MIKE OSSIPOFF]

I'd said:

>In CSSD(wv), BeatpathWinner(wv), or Ranked-Pairs(wv),
>if X is in the sincere Smith set, and Y is not, and if a majority
>prefer X to Y, and vote sincerely, and if no one falsifies a preference,
>then Y can't win. Not even if someone flips a coin :-)

Rob LG replied:

Sure, if no one "falsifies a preference". Which means it's okay for them to
vote insincere ties (like A>B=C)

I reply:

It's ok with me, because it doesn't cause a problem in wv.

Rob continues:

but not to reverse (like A>C>B). But I'd say
voting A>B=C is insincere just as A>C>B is, if a little less extreme.
According to your definition, voting A>B=C isn't falsifying a preference

I reply:

Declining to vote a preference isn't falsifying a preference.

Rob LG continues:

, but
voting 50% A>B>C and 50% A>C>B is. And what if every voter is willing to 
vote
strategically (which is obviously the kind of case I'm most interested in)?
Your guarantees don't mention that case at all.

I reply:

Actually, they do. SDSC doesn't care how you vote. If a majority
prefer A to him, then they have a way of voting that will ensure
that your candidate will lose. No matter what strategy you use.

As I said, if a majority prefer someone to him, and rank that someone,
but don't rank your candidate, then your candidate can't win in
CSSD(wv), SSD(wv) or RP(wv), no matter what strategy you try. In
fact, attempting offensive order-reversal then will worsen your
outcome.

And even the person who's willing to vote strategically might
be willing to lower himself to some strategies (truncation), but
not others (offensive order-reversal against someone who is
trying to help his candidate [those are the only people offensive
order-reversal works against in wv] ).

Aside from the matter of pride in honesty, or compunction or
conscience, there's the matter of practicality. As I said before,
the fact that reversal could benefit someone doesn't mean that
it's a wise strategy. More about that when I return to the
game-theory subject that you brought up. Well, briefly, in
wv, there's no equilibrium in which offensive order-reversal
works, if an equilibrium is taken to mean a strategy configuration
from which no one player can gain by unilaterally changing his
strategy. That's true of the typical reversal-problem example
that I'll discuss when I return to that subject. Let me post a
more complete message about that before you reply about the
equilibria. By the way, my only study of game theory was an
introductory public library book, a long time ago; no university
textbooks on game theory. I realize that game theorists have
many kinds of equilibrium that they discuss. Of the equilibria that
do exist, there's on in which no one reverses a preference. More
about that later. Obviously I should also find out more about
the subject. But if someone already knows more about it, let them
apply it to wv & margins, and tell the results.

I'd said:

>Yes, I know that you think that, with wv, voters who'd otherwise
>have only truncated would order-reverse. Even if the necessary number
>of people were inclined to do that, which is really doubtful, it
>would carry a great danger of backfiring.

Rob LG replied:

Perhaps, but strategic reversal is no more dangerous in winning-votes than 
in
margins

I reply:

Wrong. In wv, if your intended victims defensively truncate,
your order-reversal will considerably worsen your outcome, compared
to what it would have been had you not reversed. In margins,
order-reversal will only be stopped by defensive order-reversal,
and there's no penalty to the order-reversers. So you can hardly
say that offensive order-reversal isn't more dangerous in margins
than in wv. Especially since everyone will know about the
campaign to organize the reversal strategy, and especially because
if some are sophisticated enough to try reversal strategy, others
will be sophisticated enough to make them sorry.

Rob LG continues:

I personally would vote sincerely in a Condorcet election
unless I could somehow be *really* sure that a reversal would be to my
advantage (except maybe for voting high ties if a winning-votes method were
used).

I reply:

It's ok with me if you vote high ties in wv. I often would too,
but I don't consider it a serious problem, and I told why.

You wouldn't reverse, and few people would. But you might truncate,
if you were short of time, or hadn't studied the candidates. wv
guarantees against that causing the majority rule violations
that margins can thereby cause.

At the risk of sounding like the IRV promoters, all nonprobabilistic
voting systems have strategy incentive of some kind. Even wv
does. But, as you said, we can minimize the magnitude of the problem,
and wv does that too. SFC, GSFC, WDSC, SDSC are about the
strategy problems that you _won't_ have in wv, but will have in
margins.

>If the insincere voting that you're referring to is ranking in
>different rank positions candidates whom you sincerely rate equally,
>do you really think that's important?

>Rob LG, if you'll check the introductory web-page for EM, it points
>out that it isn't productive to repeat refuted arguments. We've been
>over all this before.

Rob LG continues:

I don't see winning-votes's
handling of tied preferences as doing any good if the voters are informed, 
as
I've explained.

I reply:

You mean, if they're well-informed enough to know that they
could try offensive order-reversal. Aside from the repugnance of
that strategy, you yourself said that you wouldn't try it without
being sure that it would work. Aye, there's the rub. You'd be
taking a big chance. In fact, since everyone would know about
the reversal campaign in advance of the election, it would
be guaranteed to fail.


>As for flipping coins, that of course would most likely have no
>effect in a public election, as the coin-flips and the resulting
>AB votes would tend to cancel out.

Rob LG continues:

Exactly. Under winning-votes, a bunch of voters voting half A>B>C and half
A>C>B will get the same result as if they had all voted A>B=C under margins.

I reply:

When it comes to the matter of whether or not they succeed in
making a strategic circular tie, yes, they have the same
effectiveness for doing that. But whereas margins truncation is
a slamdunk, wv offensive order-reversal will probably only gain
them a worse result than if they hadn't done it, unless everyone
else is out-to-lunch--because wv order-reversal has a simple,
easy countermeasure that imposes a penalty, unlike margins.

Rob LG continues:

If they benefit from the insincerity, then winning-votes's guarantees are
rendered ineffective.

I reply:

Wrong. Even if they could conceivably  benefit, they probably
won't, and will probably regret it. When they find that out,
and you say that they'll find out the strategic facts, then they
won't be trying it, and SFC & GSFC's benefits will be had.

Rob LG continues:

Winning-votes works only when voters are stupid enough
not to realize that they have just as many strategic options as under 
margins

I reply:

No, they can realize that they could offensively order-reverse,
and that doesn't mean that they will. You've been given a number
of reasons for that, including the fact that it will surely
backfire, since everyone will know about it, due to the
big public campaign needed to organize it.

Rob LG continues:

in fact, they have more, since margins allows no equivalent to 
winning-votes's
A=B>C.

I reply:

No 2 methods have exactly the same strategies. Ok, let them
vote A=B>C. They won't steal an election from a CW, in that way,
or cause the majority rule violations that margins lets happen.
If someone gains some advantage in the event of special kinds
of natural circular ties, that isn't important to me. If it's
important to you, you could do the same, and it would tend to
cancel out.

Rob LG said:

I pointed out how winning-votes shares every single
strategic problem that margins has when voters aren't ignorant

I reply:

So if voters aren't ignorant of the offensive order-reversal
strategy, but find that it only worsens their outcome, for the
reasons that I've described, you call that sharing margins'
strategy problems, even though stealing the election is more
difficult to prevent in margins, and the attempt is undeterred.

Rob LG continues:

, and noted that
*any* ranked-ballot method will have serious strategy problems when the
electorate is well-informed and there is no sincere Condorcet winner.
I reply:

But margins lets sincere CWs lose to truncation, and lets
truncation cause big majority rule violations and defensive
strategy problems, under conditions where it's avoidable and
won't happen in wv.

Rob LG continues:

Mike is comforted by the fact that winning-votes methods make it easier to
protect a sincere Condorcet winner when no voter reverses strategically. I'm
not.

I reply:

That's because you believe that offensive reversal will be
rampant. But consider what I've said in this message about that.

Rob LG continues:

He wants to prevent offensive "truncation".

I reply:

Well, I don't want truncation to steal elections, violate
majority rule, and cause unnecessary drastic strategy dilemmas.

Rob LG continues:

But as I've explained, a
voter could make his offensive "truncation" just as effective
(game-theoretically equivalent) under winning-votes as under margins, 
whether
by randomization or coordination.

I reply:

There's a big difference, when margins truncation needs
drastic defensive strategy to prevent its harm, likewise
margins order-reversal, and neither is deterred by margins;
and truncation has no effect in wv, and offensive order-reversal
is easily thwarted, and carries a penalty.

That doesn't sound so "equivalent" to me. In what way is it
"game theory equivalent"? When examined by game theory too,
the methods strategy situations are drastically different.

Margins has a much more complicated payoff matrix, because there
are so many more strategies, even for the simple 3-candidate
example in which some would protect the CW and others would
steal its win. In margins, protecting the CW and majority rule
depends on drastic defensive strategies not needed in wv.

Rob continued:

But if you agree with me that
winning-votes is actually "easy to get around", then margins makes more 
sense

I reply:

Depends on what you call "easy". Trying order-reversal instead
of truncation, and having it result in a worse outcome than if
you hadn't tried it, doesn't sound to me like an easy way to
get around the loss of margins' easy truncation election-steal.

Besides, the truncation that will cause the big majority rule
violations in margins needn't even be strategically-intended.
Most of it will be lazy. Those nonstrategic truncators aren't
going to find another strategy to replace truncation when their
innocent nonstrategic truncation no longer causes margins'
majority rule violations.

Rob continues:

,
being better at social utility and arguably more intuitive for the voter.

I reply:

SU similations aren't as reliable as you seem to believe. The
meaningfulness of their results depends on the accuracy of the
model. Models have been very simple.

Mike Ossipoff


_________________________________________________________________
Send and receive Hotmail on your mobile device: http://mobile.msn.com