[EM] Symmetric ICT reformulation and exploration

Sat Nov 12 21:29:35 PST 2016

Yes, it would make sense, and be interesting for a voting-system reform
proposal to include CVT in its list of offered methods. Offer a complete
variety, and let the initiative committee &/or the public choose. The
addition of CVT would greatly broaden the variety. So the list could be:

Approval
Score
Bucklin
MDDTR
CVT

Actually, it might be best to include IRV, with a fair assessment of its
advantages & disadvantages, so that people won't think that IRV is being
prejudcially ignored, and so as to answer, in advance, any arguments from
FairVote.

Michael Ossipoff

On Sat, Nov 12, 2016 at 7:54 PM, Forest Simmons <fsimmons at pcc.edu> wrote:

> How about including CTV (Candidate Transfer Voting)?
>
> Ballots are Plurality style.
>
> If no candidate has a majority of votes, then the candidate with the
> fewest votes distributes hir votes among the other candidates. Transfers
> continue until some candidate has a majority.
>
> Under these rules the method is CD compliant.
>
> A slight tweak makes it harder to spoil the ballot:  If a voter marks
> several candidates, then hir vote is distributed equally (i.e.
> fractionally) among the marked candidates.
>
> I have found this idea to be easy to sell to people that like neither IRV
> nor Approval.  They don't like IRV because ranking is too much trouble for
> a method that fails FBC.  They don't like Approval because they don't want
> to think about whom they should approve beyond their Favorite.
>
> Under CVT you can vote Favorite-only or vote your Top set; it is very
> close to optimal either way.  No muss no fuss,
>
> Like Approval, CTV externalizes or side-steps most if not all of the
> standard academic paradoxes (Gibbard-Satterthwaite, Arrow, etc.)
>
> By making the transfer protocol less structured you can sidestep even the
> center squeeze objection.  For example you let the candidates transfer in
> any order that they like with the only limit being a time limit; after 72
> hours if no candidate has a majority of votes, then the candidate with the
> greatest number of votes so far is the winner. (It might be the candidate
> who can survive the longest on takeout.) There may or may not still be a
> de-facto center-squeeze problem in an election, but that is only a relic of
> the candidates' negotiation inadequacies, not a necessary feature of the
> method itself.
>
> The method has an history.  I don't know all of it, but Charles Dodgson
> (a.k.a. Lewis Carroll) recommended it as being the most practical method
> for public elections.
>
> [The method that goes by his name is a computationally NP-hard Condorcet
> method that he would never recommend for public elections.]
>
> One version or another of CTV is used all of the time in groups like
> corporation boards and parliaments that allow members to delegate their
> votes to proxies.
>
> In STV elections where the majority of voters copy rankings from party or
> candidate cards, there is no substantial difference except that CTV is many
> orders of magnitude simpler.
>
>
> *
> <http://r.search.yahoo.com/_ylt=A0LEV7pwsSdYUQoAsHUnnIlQ;_ylu=X3oDMTE0MTJtMWwwBGNvbG8DYmYxBHBvcwMxBHZ0aWQDRkZVSTNDMV8xBHNlYwNzcg--/RV=2/RE=1479025136/RO=10/RU=https%3a%2f%2fen.wikipedia.org%2fwiki%2fGibbard%25E2%2580%2593Satterthwaite_theorem/RK=0/RS=whh0fKkusSMUhWsgAOci_kDAPHg->*
>
> *
> <http://r.search.yahoo.com/_ylt=A0LEV7pwsSdYUQoAsHUnnIlQ;_ylu=X3oDMTE0MTJtMWwwBGNvbG8DYmYxBHBvcwMxBHZ0aWQDRkZVSTNDMV8xBHNlYwNzcg--/RV=2/RE=1479025136/RO=10/RU=https%3a%2f%2fen.wikipedia.org%2fwiki%2fGibbard%25E2%2580%2593Satterthwaite_theorem/RK=0/RS=whh0fKkusSMUhWsgAOci_kDAPHg->*
> .
>
>
> *
> <http://r.search.yahoo.com/_ylt=A0LEV7pwsSdYUQoAsHUnnIlQ;_ylu=X3oDMTE0MTJtMWwwBGNvbG8DYmYxBHBvcwMxBHZ0aWQDRkZVSTNDMV8xBHNlYwNzcg--/RV=2/RE=1479025136/RO=10/RU=https%3a%2f%2fen.wikipedia.org%2fwiki%2fGibbard%25E2%2580%2593Satterthwaite_theorem/RK=0/RS=whh0fKkusSMUhWsgAOci_kDAPHg->*
>
>
> *
> <http://r.search.yahoo.com/_ylt=A0LEV7pwsSdYUQoAsHUnnIlQ;_ylu=X3oDMTE0MTJtMWwwBGNvbG8DYmYxBHBvcwMxBHZ0aWQDRkZVSTNDMV8xBHNlYwNzcg--/RV=2/RE=1479025136/RO=10/RU=https%3a%2f%2fen.wikipedia.org%2fwiki%2fGibbard%25E2%2580%2593Satterthwaite_theorem/RK=0/RS=whh0fKkusSMUhWsgAOci_kDAPHg->*
>
>
>
>
>
> On Sat, Nov 12, 2016 at 2:41 PM, Michael Ossipoff <email9648742 at gmail.com>
> wrote:
>
>> I'd say that MDDTR is better, but I'd guess that Buckln might be more
>> likely to get enacted, because of its use-prededent, and because opponents
>> could use Mono-Add-Plump against MDDTR (and proponents might not have as
>> much media availabiliy to answer adequately).
>>
>> But a proposal should include all of the best possibilities:
>>
>> Approval
>> Score
>> Bucklin
>> MDDTR (re-named "Majority-Disqualification")
>>
>> Then, the initiative-proposal-committee, and the public, via polls &
>> focus-groups, would choose among those methods, for the initiative.
>>
>> I'd say that Approval's plain naturalness & obviousness, an its no-cost
>> implementation would make it the easiest & most easily enacted 1st reform
>> from Plurality.
>>
>> Michael Ossipoff
>>
>> On Sat, Nov 12, 2016 at 4:46 PM, Michael Ossipoff <email9648742 at gmail.com
>> > wrote:
>>
>>> I forgot to add Mono-Add-Plump to the advantages of Buclin over MDDTR.
>>> So it should say:
>>>
>>> Bucklin:
>>>
>>> * Mono-Add-Plump
>>>
>>> * Use-Precedence
>>>
>>> * Easier protection of the CWs
>>>
>>> MDDTR:
>>>
>>> *CD
>>>
>>> *LNHa
>>>
>>> * Precinct-Summabilty
>>>
>>> -----------------------------------------
>>>
>>> If Bucklin's easier protection is in question, then the comparison is
>>> especially more favorable to MDDTR.
>>>
>>> Michael Ossipoff
>>>
>>>
>>>
>>> On Sat, Nov 12, 2016 at 4:32 PM, Michael Ossipoff <
>>> email9648742 at gmail.com> wrote:
>>>
>>>> Yes, that 2/3 majority rule would avoid having to say:
>>>>
>>>> "(If each candidate has someone rated over hir by a majority, then the
>>>> winner is the most top-rated candidate.)"
>>>>
>>>> Tantalizingly greater simplicity, regrettably not workable, as you said.
>>>>
>>>> ICT would avoid the Mono-Add-Plump criticism, but at the cost of
>>>> truncation-vulnerability.
>>>> I'd rather have the Mono-Add-Plump criticism and truncation-proofness.
>>>>
>>>> The ICT wording you described comes closer to the brevity of MDDTR, but
>>>> MDDTR doesn't need a separate "beat" definition at all. ...just the use of
>>>> the already-understood majority.
>>>>
>>>> I suggested the 3-slot version of MDDTR because I felt that it should
>>>> be used only as an Approval-version, with the Middle rating reserved for
>>>> the special chicken-dilemma situation.   ...because I felt that MDDTR, with
>>>> its complete vulnerability to burial (like every pairwise-count method),
>>>> wouldn't be good as a rank-method.
>>>>
>>>> But maybe that should be reconsidered. Why would it be worse to rank
>>>> your inbetween candidates in order of preference, than to rate them all
>>>> together at middle?
>>>>
>>>> The burial-vulnerability, the fact that "wv-like" didn't mean as much
>>>> as I'd believed it did,  was such a disappointment that it at first made me
>>>> not appreciate the fact that MDDTR still has truncation-resistance. Burial
>>>> vulnerability isn't a complete disaster:
>>>>
>>>> For one thing, to bury the CWs, you have to know who is the CWs. And if
>>>> you know it, then the defending wing knows it too, because the same
>>>> predictive information is available to everyone.
>>>>
>>>> If the CWs is more  with your wing, and it's the opposite wing that
>>>> dislikes the CWs, and is likely to bury, you can prevent successful burial
>>>> by equal-top-ranking the CWs. That was pointed out a long time ago, as
>>>> general pairwise-count defensive strategy.
>>>>
>>>> You could protect the CWs in that way in Bucklin too. (in case people
>>>> might rank past the CWs).
>>>>
>>>> Of course the difference is that, in Buclin you & the others in your
>>>> wing can also just avoid ranking past the CWse (expected or evident CWs).
>>>>
>>>> MDDTR, and pairwise-count methods in general, don't have that
>>>> protection, and you only have the defensive strategy of equal-top-ranking
>>>> the CWse.
>>>>
>>>> So, as regards protection of the CWs, Bucklin is better than the
>>>> pairwise-count methods. MDDTR's tradeoff-advantage is its CD.  ...in return
>>>> for being able to protect the CWs only by equal-top-ranking.
>>>>
>>>> Conditional Bucklin's and Conditional Approval's FBC failure is of a
>>>> different kind than Condorcet's FBC failure, it seems to me. With
>>>> Conditional Bucklin, the effectiveness of my equal-top-ranking isn't
>>>> diminished by the FBC failure. The FBC failure merely gives me a trick that
>>>> I could use, with sufficient predictive information, to gain advantage. Not
>>>> a problem. But the problem is that the serious overcompromiser would still
>>>> have incentive to rank Hillary alone at top, over the overompromiser's
>>>> favorite. So I guess I reluctantly have to not advocate Conditional Bucklin
>>>> or Conditional Approval.
>>>>
>>>> ...meaning that evidently Bucklin can't have CD, and MDDTR's CD is an
>>>> advantage for MDDTR over Bucklin.  So it's MDDTR's CD vs Bucklin's easier
>>>> protection of the CWs.
>>>>
>>>> All that time I was calling wv burial-deterrent, because of the
>>>> 3-candidate example, where deterrence is achieved by merely not ranking the
>>>> would-be buriers' candidate, I never considered a 4-candidate example.
>>>>
>>>> It's easy to make a 4-candidate example where, in wv (& in MDDTR), that
>>>> defense won't work: If B is the CWs, and the A voters are going to bury by
>>>> insincerely ranking C over B, then just add D, between B and C.
>>>>
>>>> The halfway point between D & C is of course way C-ward from the
>>>> median, and so D will have a majority against C, if voters are
>>>> uniformly-distributed. (...and probably could, with suitable
>>>> distance-relations, even if the voter-distribution is Gaussian).
>>>>
>>>> So, when the A voters make B majority-beaten, by ranking C over B, C
>>>> remains majority-beaten (by D), and so now everyone is majority-beaten, and
>>>> A wins if s/he's the most top-rated.
>>>>
>>>> I haven't looked at what it would take for A to win in wv, because I no
>>>> longer propose wv for official public political elections (or any where
>>>> offensive strategy is likely). That would be something for a wv advocate to
>>>> discuss.
>>>>
>>>> Maybe I should list, together, some relative advantages of Bucklin &
>>>> MDDTR:
>>>>
>>>> Bucklin:
>>>>
>>>> * Easier protection of the CWs (relevant if one of your inbetween might
>>>> be the CWs)
>>>>
>>>> * Use-precedence
>>>>
>>>> MDDTR:
>>>>
>>>> * CD
>>>>
>>>> * LNHa
>>>>
>>>> * Precinct-Summability
>>>>
>>>> ----------------------------------------------------------------
>>>>
>>>> As for Bucklin's easier protection of the CWs, I'm not entirely sure,
>>>> because there's some reason for the individual to rank all of the best
>>>> candidates (instead of only ranking down to the CWse), to improve,
>>>> somewhat, the probabiliy of electing one of them (but not as much as
>>>> equal-top-ranking them all). So I don't know if Bucklin's easier protection
>>>> of the CWs would materialize..
>>>>
>>>> Michael Ossipoff
>>>>
>>>>
>>>>
>>>>
>>>>
>>>>
>>>>
>>>> Michael Ossipoff
>>>>
>>>>
>>>>
>>>>
>>>>
>>>> Maybe a toss-up. Bucklin has the use-precedence advantage, but MDDTR
>>>> has the precinct-summability adantage. And I consider MDDTR's LNHa an
>>>> advantage too, when you don't have to hesitate to append less-liked
>>>> inbetweens to your ranking for fear that you'll help the beat better
>>>> candidaes.
>>>>
>>>> In Bucklin, when skipping is permitted, you could make sure that, above
>>>> some inbetween, you skip enough levels that the better candidates will have
>>>> enough rounds to accumulate the coalescing lower-choices that are coming to
>>>> them from other candidates' preferrers.
>>>>
>>>> In MDDTR, & maybe in Bucklin, I'd likely top-rate the CWse, along with
>>>> the very best of the strong top-set, even if s/he isn't really among those,
>>>> and even if I felt like down-rating some of that top-set a bit because of
>>>> some fault, or because of likely defection-inclination of their voters.
>>>>
>>>>
>>>>
>>>>
>>>>
>>>>
>>>> On Sat, Nov 12, 2016 at 2:56 PM, Forest Simmons <fsimmons at pcc.edu>
>>>> wrote:
>>>>
>>>>> Perhaps we could modify (non-symmetric) ICT in order to have a less
>>>>> wordy definition of "strongly beat."
>>>>>
>>>>> Candidate X *strongly beats* candidate Y iff  X is preferred over Y
>>>>> on more ballots than Y is* ranked* equal to or above X.
>>>>>
>>>>> All strongly beaten candidates are disqualified unless that would
>>>>> disqualify all of them.
>>>>>
>>>>> Elect the qualified candidate ranked top on the most ballots.
>>>>>
>>>>> This definition makes it slightly harder for X to strongly beat Y than
>>>>> in standard ICT, because all equal rankings have to be overcome, not only
>>>>> those at the top.
>>>>>
>>>>> But it changes nothing in our standard CD examples, because in those
>>>>> examples there are no equal rankings (only equal truncations, which don't
>>>>> contribute to the strongly beat definition).
>>>>>
>>>>> It should preserve the FBC and perhaps even introduce a stronger
>>>>> property: if some candidate X is raised to the level of the winner on some
>>>>> ballots, then the winner is unchanged unless the new winner is X.
>>>>>
>>>>> I see the wisdom in saying "disqualified" instead of "eliminated."  If
>>>>> we said "eliminated," then some people would wrongly think that "favorite"
>>>>> refers to the highest among the remaining candidates (after their original
>>>>> favorite was stricken from the ballot).
>>>>>
>>>>> Also a comment about three slot methods in general:
>>>>>
>>>>> With three slots it is impossible for every candidate to be eliminated
>>>>> by a two-thirds majority.  So the following method would be even simpler to
>>>>> define in the context of 3 slot ballots:
>>>>>
>>>>> Elect the favorite candidate who is not beaten by a two-thirds
>>>>> majority.
>>>>>
>>>>> Of course, for all practical purposes that would be the same as "elect
>>>>> the candidate ranked top on the greatest number of ballots," which doesn't
>>>>> satisfy the CD criterion.
>>>>>
>>>>>
>>>>> On Sat, Nov 12, 2016 at 9:07 AM, Michael Ossipoff <
>>>>> email9648742 at gmail.com> wrote:
>>>>>
>>>>>> Yes, but ICT defines "beat" in a wordier way, that people hear as
>>>>>> complicated.
>>>>>>
>>>>>> For people who are into voting-systems, I can say "majority-beaten",
>>>>>> & they know what I mean...that I'm talking about pairwise defeats.
>>>>>>
>>>>>> So, here's how I'd define 3-Slot MDDTR, to the public:
>>>>>>
>>>>>> You rate each candidate as  "Top", "Middle", or "Bottom". If you
>>>>>> don't rate someone, that counts as rating hir at Bottom.
>>>>>>
>>>>>> The winner is the most    favorite candidate who doesn't have anyone
>>>>>> rated over hir by a majority.
>>>>>>
>>>>>> (If everyone has someone rated over hir by a majority, then the
>>>>>> winner is the most favorite candidate.)
>>>>>>
>>>>>> (end of definition)
>>>>>>
>>>>>> I'd just call it " Majority Disqualification".
>>>>>>
>>>>>> Michael Ossipoff
>>>>>> On Nov 11, 2016 4:39 PM, "Forest Simmons" <fsimmons at pcc.edu> wrote:
>>>>>>
>>>>>>> You wrote in part ...
>>>>>>>
>>>>>>> >Another advantage that it has over 3-Slot ICT is that 3-Slot MDDTR
>>>>>>> has a much >simpler definition:
>>>>>>>
>>>>>>> >The winner is the most favorite candidate who isn't majority-beaten.
>>>>>>>
>>>>>>> Three slot ICT could be defined in the same way;
>>>>>>>
>>>>>>> Elect the most favorite candidate who isn't strongly beaten.
>>>>>>>
>>>>>>> Neither definition tells what to do when every candidate is beaten
>>>>>>> (majority beaten or strongly beaten, respectively).  But that is just a
>>>>>>> detail of the definition that doesn't have to be mentioned immediately.
>>>>>>>
>>>>>>> Here's a more complete definition that works in both cases:
>>>>>>>
>>>>>>> Eliminate all candidates that are {majority, strongly} beaten unless
>>>>>>> that would eliminate all candidates.  Elect the most favorite among the
>>>>>>> remaining.
>>>>>>>
>>>>>>> So ordinary ICT and MDDTR are equally easy to define.  It's a matter
>>>>>>> of which has the best properties.
>>>>>>>
>>>>>>
>>>>>
>>>>
>>>
>>
>
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