[EM] FBC, center squeeze, and CD

[Michael Ossipoff]

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>
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 why IRV was repealed in Burlington.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>
> wrote:
>
>>
>>
>> On Sun, Nov 6, 2016 at 11:24 PM, C.Benham <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> 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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