[EM] FBC, center squeeze, and CD
C.Benham
cbenham at adam.com.au
Tue Nov 8 08:46:40 PST 2016
On 11/8/2016 8:14 AM, Michael Ossipoff wrote:
> I should re-state the definition of MDDTR, because we haven't
> discussed it for a while.
>
> Ii don't know who introuced MDDTR. Who introduced it?
I think you did. There was a 3-slot MDDA:
http://wiki.electorama.com/wiki/Majority_Defeat_Disqualification_Approval
> MDDTR:
>
> Voters can rank as many or as few candidates as they want to.
I surprised you aren't proposing that it use 3-slot rating ballots.
The method obviously has a horrible strong random-fill incentive.
Chris Benham
> I should re-state the definition of MDDTR, because we haven't
> discussed it for a while.
>
> Ii don't know who introuced MDDTR. Who introduced it?
>
> MDDTR stands for Majority Defeat Disqualification, Top Ratings.
>
> MDDTR:
>
> Voters can rank as many or as few candidates as they want to.
>
> Equal rankings allowed.
>
> 1. Disqualify any candidate who has a majority pairwise defeat, unless
> everyone has one.
>
> 2. The winner is the un-disqualified candidate top-ranked by the most
> voters.
>
> [end of definition]
>
> MDDTR meets FBC & CD, an has wv-like stratgy.
>
> The cost for that is that MDDTR fails Mono-Add-Plump. I've discussed
> what that is no worse than IRV's failure of Mono-Raise. If IRV can be
> popular in spite of Mono-Raise failure, and its favorite-burial need,
> then MDDTR's Mono-Add-Plump failure shouldn't have its importance &
> badness exaggerated.
>
> IRV is popular here. Then there's no reason why MDDTR couldn't or
> shouldn't be at least as popular.
>
> Michael Ossipoff
>
>
>
> On Mon, Nov 7, 2016 at 4:32 PM, Michael Ossipoff
> <email9648742 at gmail.com <mailto:email9648742 at gmail.com>> wrote:
>
>
> Chris--
>
> You suggested that Mono-Add-Plump failure is worse than Mono-Raise
> failure because people care more about their favorites, and
> because Mono-Raise failure is simpler.
>
> 1. Caring about favorites:
>
> a) So you're saying that Mono-Raise failure can't happen when
> someone sincerely moves their favorite to top?:
>
> IRV:
>
> 31: A
> 2: B>A (sincere is A)
> 29: B>C
> 30: C>A
>
> 1st round totals:
>
> A = 31
> B = 29 + 2 = 31
> C = 30
>
> C is eliminated & transferss to A
>
> Now A has a 61 majority and wins.
>
> But then the 2 B>A voters decide to sincerely raise A to top:
>
> 33: A
> 29: B
> 30: C
>
> B gets eliminated, and transfers to C.
>
> Now C has a 59 majority and wins.
>
> b) You care about favorite? What about when you need to rank
> Comprmise over favorite to keep worst from winning? We're all
> familiar with that. In Burlington, the Republicans didn't do that,
> and their failure to favorite-bury elected their last choice.
>
> Yes, this isn't a monotonicity failure, but you used caring about
> Favorite as an advantage of IRV's Mono-Raise failure over MDDTR's
> Mono-Add-Plump failure. But obviously IRV has a bigger problem for
> Favorite. ...the reason why IRV was repealed in Burlington.
>
> So please, let's not use caring about Favorite as a reason to
> prefer IRV with its Mono-Raise failure
> & its favorite-burial need, to MDDTR's Mono-Add Plump failure.
>
> 2. Simplicity:
>
> What could be simpler than your need, in IRV, to bury your
> favorite to help Compromise beat Worst:
>
> Sincere:
>
> 40: C
> 25: B>C
> 35: A>B
>
> A voters vote sincerely, and B, the CWv, gets eliminated &
> transfers to C. C wins because the A voters didn't favorite-bury.
>
> Strategic:
>
> 40: C
> 25: B>C
> 35: B>A (sincere is A>B)
>
> Now B wins.
>
> That's as simple as it gets. Let's not say that MDDTR's look-bad
> criterion-failurle is simpler than IRV's serious favorite-burial need.
>
> Yes, I'm talking about a problem that isn't a monotonicity
> problem. But its at least as simple as MDDTR's Mono-Add-Plump
> problem, and is worse because it's a practical strategy problem
> that makes people need to favorite-bury.
>
> Michael Ossipoff
>
>
> By sincerely raising A to top, you made A lose.
>
>
>
>
>
>
>
>
> On Mon, Nov 7, 2016 at 2:48 AM, Michael Ossipoff
> <email9648742 at gmail.com <mailto:email9648742 at gmail.com>> wrote:
>
>
>
> On Sun, Nov 6, 2016 at 11:24 PM, C.Benham <cbenham at adam.com.au
> <mailto:cbenham at adam.com.au>> wrote:
>
> On 11/7/2016 6:07 AM, Michael Ossipoff wrote:
>> ...someone could say. "You didn't just favor X. You added
>> a ballot, thereby spoiling a majority. It has nothing to
>> do with the fact that you voted for X. You could have
>> plumped for any of various candidates, and the effect
>> would have been exacsly the same."
>
> "Someone" could /say/ that, but it wouldn't make any sense.
>
>
> But how so?
>
>
>> But you can't say anything like that to to explain why X
>> lost when I raised hir in my ranking. In that instance,
>> making the ballot-set more favorable to X is the _only_
>> thing that I'm doing.
>
> Increasing the turnout is generally regarded as a good
> thing. If the method used was one of the mono-raise
> failing methods I like (such as IRV and Benham), I would say:
>
> "Unfortunately it isn't possible for voting methods to
> have every desirable property (because some of those
> properties are mutually incompatible), and this method
> economises
> by not meeting mono-raise.
>
>
> Exactly. The more properties, important desirable ones, a
> method provides, the more of a cost there is, in terms of
> "embarrassment criteria", "could-look-bad".
>
> So it's a matter of what you're getting in terms of the
> "could-look-bad", and whether that could-look-bad could be bad
> in a practical way. As you suggested, MMPO's
> "Hitler-with-2-votes" would be bad news, and, as you
> suggested, is more than a "look-bad".
>
> But the Mono-Raise failure of Benham, Woodall & IRV is only a
> could-look-bad. It never bothered me, and never stopped me
> from saying good thins about those methods.
>
> Likewise the lesser look-bad of MDDTR, when it fails
> Mono-Add-Plump.
>
> MDDTR meets FBC & CD, and it has wv-like strategy.
>
> ...the same advantages that MMPO has.
>
> ...at the cost of Mono-Add-Plump.
>
> You like IRV, Benham & Woodall. Lots of people here love IRV.
> I don't reject those methods, though they aren't my main
> proposals, because of FBC, and the fact that there's nothing
> the CWs's voters can do to protects hir from losing, and the
> fact that Benham & Woodall are pairwise-count methods very
> vulnerable to pairwise-count offensive strategy, and innocent,
> nonstrategic truncation.
>
> If you aren't majority-favored, the elimination of the CWs is
> disadvantages for you. But, in Bucklin, sometimes it might not
> be known who the CWs is, and s/he might not defenseiveliy
> plump, and so s/he (& you too) lose anyway, even though it
> isn't IRV. I don't know that the Bucklin failure that I just
> described will be rarer than the IRV failure that I just
> described. And IRV brings some big advantages for people who
> are majority-favored...MMC, CD, LNHa, LNHe.
>
> If your candidate is big enough to eliminate the CW, then
> s/he's big enough that s/he's fairly well-known, and that CW's
> voters would know something about hir, and would be unlikely
> to reject hir & transfer the other way when s/he's close
> enough to what you want that you'd prefer to elect hir.
>
> So I don't reject IRV--I just don't emphasize it as a proposal.
>
> Anyway, as I said, lots of people here love IRV, and its
> Mono-Raise failure doesn't seem to hurt its popularity. You
> like IRV, and its Mono-Raise failure doesn't put you off from
> it. I agree with you on that.
>
> And, for the same reason, we needn't & shouldn't be put off by
> MDDTR's Mono-Add-Plump failure.
>
>
>
> But generally speaking people care most about their favourites
>
>
> True.
>
> , and IRV meets not only mono-add-plump but also
> mono-add-top. It's true that after the election
> some of losing candidate X's supporters could complain "If
> we hadn't top-ranked X, then X would have won" but that is
> unlikely to be noticed and of course isn't
> true of all (or anything like all) of X's supporters. So
> the X supporters as a whole could complain "If we had been
> well informed and coordinated we could have
> used a mixed strategy (with not all of us voting the same
> way) and elected X."
>
> But if voters accept the method as fair and legitimate
> then that "complaint" won't be taken seriously or get much
> sympathy.
>
>
> ...as with MDDTR.
>
>
> Just as no quasi-intelligent device should be so "stupid"
> as to be confused by the very simple and spectacular MMPO
> failure example, neither should it be
> confused by the very very simple mono-add-plump scenario.
>
>
> ...or the fact that in IRV you can make someone lose by
> ranking them higher?
>
>
> What (arguably) desirable properties (or criterion
> compliances) are incompatible with meeting Mono-add-Plump?
>
>
> FBC, CD, & wv-like strategy are evidently require failing
> Mono-Add-Plump, or having MMPO's Hitler-with-2-votes problem.
>
> With MDDTR, the price of FBC, CD & wv-like strategy is
> Mono-Add-Plump. That's a very small price, arguably less than
> IRV's Mono-Raise failure (though I note that you mentioned
> that Mono-Add-Plump is about a favorite).
>
> Michael Ossipoff
>
>
> Chris Benham
>
>
>> Ok, thanks, Chris, for settling that matter. I guess we
>> have to reluctantly give up Conditional Bucklin.
>>
>> But it would have been strategically great!
>>
>> Now, here's a question on a related topic:
>>
>> Say I arrive at the polling-place late. Before I arrive X
>> is winning. I show up & plump for X, and that causes X to
>> lose.
>>
>>
>> ...is that worse than if I raise X in my ranking, and
>> that causes X to lose?
>>
>> If so, why?
>>
>> It seems to me that the latter is worse than the former.
>>
>> I if show up late and plump for X, I'm doing two things:
>> I'm adding a ballot, and I'm voting that ballot in a way
>> that clearly should favor X.
>>
>> If i angrily complain, "Hey, how come, when I arrived and
>> plumped for X, that made X lose??!"
>>
>> ...someone could say. "You didn't just favor X. You added
>> a ballot, thereby spoiling a majority. It has nothing to
>> do with the fact that you voted for X. You could have
>> plumped for any of various candidates, and the effect
>> would have been exacsly the same."
>>
>> But you can't say anything like that to to explain why X
>> lost when I raised hir in my ranking. In that instance,
>> making the ballot-set more favorable to X is the _only_
>> thing that I'm doing.
>>
>> So plainly violating Mono-Raise is worse than violating
>> Mono-Add-Plump.
>>
>> Michael Ossipoff
>>
>>
>>
>> On Sun, Nov 6, 2016 at 10:27 AM, C.Benham
>> <cbenham at adam.com.au <mailto:cbenham at adam.com.au>> wrote:
>>
>> The example I just posted of "IBIFA with an
>> anti-defection device" failing FBC I'm afraid also
>> works for both Mike's suggested
>> "Conditional Bucklin" and Forest's suggested
>> "TopMiddleBottom".
>>
>> 20: F=C >>B
>> 07: F > C=B (or, for the sake of Forest's method
>> suggestion, F >> C=B)
>> 25: B
>> 48: W
>>
>> All three of these methods elect W, but if the 20 F=C
>> >> B voters change their rating of F from Top to
>> Middle or Bottom
>> then the winner changes to B.
>>
>> Chris Benham
>>
>>
>>
>
>
>
>
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