[EM] Strategy-free criterion

[Closed Limelike Curves]

*or because it might violate my privacy." (Sorry for the incomplete
sentence.)

On Sat, Jun 22, 2024 at 3:31 PM Closed Limelike Curves <
closed.limelike.curves at gmail.com> wrote:

> Chris, sorry if I wasn't clear enough with this statement:
>
>> An equal-ranking isn’t a way to express indifference (or else equal-ranks
>> would never happen); it’s a way of pleading the fifth. Learng that a voter
>> refuses to say whether they prefer Bob or Bill provides an important piece
>> of information.
>
> In the United States, Americans have a constitutional right to refuse to
> answer any question they're asked by a police officer or other government
> official. This is guaranteed by the fifth amendment, and is intended to
> prevent forced confessions. This extends to guilty pleas, and someone who
> invokes this right is described as "pleading the fifth (amendment)".
>
> Someone who pleads the fifth, in response to an accusation of the crime,
> is saying "I refuse to provide this information, because it might be
> harmful to me, or because it might ."
>
> Here's an example of a realistic situation where this applies. Say we have
> a paired matchup where Donald Trump defeats Mitt Romney by 36%-29%, because
> most Republicans prefer Trump. Most Democrats truncate their ballots and
> refuse to rank either, which might hurt them: if they support Romney, he
> might defeat the Democratic candidate.
>
> In this situation, we have to work out what their opinions are. So, isn't
> it reasonable to say this isn't a real victory for Trump at all? It's
> perfectly reasonable—probable, even—that Romney is much more popular than
> he looks here, and the only reason Trump looks like he beats is because he
> has a small but extreme base of supporters. Similarly, what if some
> Alexandria Ocasio-Cortez voters bullet-vote for moral reasons or because
> they're overconfident in their chances of victory, and don't want to give a
> win away to a more moderate Democrat? Wouldn't it reasonable to infer that
> these AOC supporters, despite ranking all the viable candidates equally,
> *do* actually support Clinton as their second choice?
>
> On Mon, Jun 10, 2024 at 4:35 AM Chris Benham <cbenhamau at yahoo.com.au>
> wrote:
>
>> CLC,
>>
>> I assume no-one posts a ballot "intending to be irrelevant"  (and whether
>> they do or not I don't see as relevant).
>>
>> Normally I wouldn't expect irrelevant ballots to be literally "empty",
>> just containing no information about any of the remotely viable information.
>>
>> An equal-ranking isn’t a way to express indifference (or else equal-ranks
>> would never happen); it’s a way of pleading the fifth
>>
>>
>> What?
>>
>> Learning that a voter refuses to say whether they prefer Bob or Bill
>> provides an important piece of information.
>>
>> Which is?
>>
>> Learning a voter has cast a completely blank ballot is an extreme case,
>> where the ballot provides a very important piece of information: it means
>> the voter expects a participation failure, because a nonempty ballot
>> will hurt them.
>>
>>
>> But an empty one might "help" them ??  Hilarious.
>>
>> A rational response to this is to raise the threshold for a defeat,
>> because setting the bar for a defeat closer to 50% prevents cycles (and
>> therefore participation failures). In other words, these ballots are
>> *very* relevant.
>>
>>
>> Of course, you anonymous STAR Voting advocate.
>>
>> Chris B.
>>
>> On 7/06/2024 1:33 am, Closed Limelike Curves wrote:
>>
>> Yeah, MAMPO seems like it might behave more sensibly there.
>>
>> IIB doesn’t make sense to me outside of positional voting systems (which
>> trivially satisfy it). If an empty ballot was genuinely intended to be
>> irrelevant, the voter wouldn’t have cast it in the first place. An
>> equal-ranking isn’t a way to express indifference (or else equal-ranks
>> would never happen); it’s a way of pleading the fifth. Learning that a
>> voter refuses to say whether they prefer Bob or Bill provides an important
>> piece of information.
>>
>> Learning a voter has cast a completely blank ballot is an extreme case,
>> where the ballot provides a very important piece of information: it means
>> the voter expects a participation failure, because a nonempty ballot
>> will hurt them.
>>
>> A rational response to this is to raise the threshold for a defeat,
>> because setting the bar for a defeat closer to 50% prevents cycles (and
>> therefore participation failures). In other words, these ballots are
>> *very* relevant.
>>
>> On Thu, Jun 6, 2024 at 7:40 AM Chris Benham <cbenhamau at yahoo.com.au>
>> wrote:
>>
>>> Kevin,
>>>
>>> I would not like to see SFC as totally obsolete, since it was one of the motivating
>>> criteria (along with MD and weak FBC) for my methods MDDA and MAMPO :)
>>>
>>>
>>> Inventing those methods was some achievement as a thought experiment to
>>> demonstrate that certain criteria are mutually compatible.
>>>
>>> But MDDA spectacularly fails the maximum-absurdity criterion
>>> Mono-add-Plump, a very interesting fact that isn't mentioned on its
>>> electowiki page.
>>>
>>> https://electowiki.org/wiki/Majority_Defeat_Disqualification_Approval
>>>
>>> Procedure
>>>
>>> The voter submits a ranking of the candidates. The candidates explicitly
>>> ranked are considered *approved* by that voter.
>>>
>>> A candidate is *dominated* if more than half of the voters rank some
>>> other candidate strictly above him.
>>>
>>> All dominated candidates are eliminated, unless this would eliminate all
>>> the candidates.
>>>
>>> Of remaining candidates, the one approved by the most voters is elected.
>>> Criteria
>>>
>>> *MDDA* satisfies the Favorite Betrayal criterion
>>> <https://electowiki.org/wiki/Favorite_Betrayal_criterion>, Strategy-Free
>>> criterion <https://electowiki.org/wiki/Strategy-Free_criterion>, the Strong
>>> Defensive Strategy criterion
>>> <https://electowiki.org/wiki/Strong_Defensive_Strategy_criterion> (and Minimal
>>> Defense criterion
>>> <https://electowiki.org/wiki/Minimal_Defense_criterion>), and
>>> monotonicity <https://electowiki.org/wiki/Monotonicity_criterion>.
>>>
>>> It fails Clone-Winner <https://electowiki.org/wiki/Strategic_nomination>,
>>> the Plurality criterion
>>> <https://electowiki.org/wiki/Plurality_criterion>, the Generalized
>>> Strategy-Free criterion
>>> <https://electowiki.org/wiki/Generalized_Strategy-Free_criterion>, the Condorcet
>>> criterion <https://electowiki.org/wiki/Condorcet_criterion>, the Smith
>>> criterion <https://electowiki.org/wiki/Smith_set>, Participation
>>> <https://electowiki.org/wiki/Participation_criterion>, the Majority
>>> criterion for solid coalitions
>>> <https://electowiki.org/wiki/Majority_criterion>, and Later-no-harm
>>> <https://electowiki.org/wiki/Later-no-harm_criterion>.
>>>
>>>
>>> 25: A>B
>>> 26: B>C
>>> 23: C>A
>>> 04: C
>>>
>>> 78 ballots (majority threshold = 40)
>>>
>>> B>C 51-27,   C>A 53-25,   A>B 48-26.  Implicit Approval scores: C 53,  B 51, A 48.
>>>
>>> All the candidates have a majority-strength defeat, so none are eliminated and the most approved candidate, C, wins.
>>>
>>> Say we now add 22 ballots that all plump (i.e. bullet vote) for C:
>>>
>>> 25: A>B
>>> 26: B>C
>>> 23: C>A
>>> 26: C
>>>
>>> 100 ballots (majority threshold = 51)
>>>
>>> B>C 51-49,   C>A 75-25,   A>B 48-26.  Implicit Approval scores: C 75,  B 51, A 48.
>>>
>>> Now only B is without a "majority-strength defeat", so the winner changes from C to B.
>>>
>>> Of course the method also fails Irrelevant Ballots Independence. If we now add 3 ballots that plump for X, the majority threshold rises to 52 and so C's majority-strength defeat goes away and C wins again by being the most approved candidate.
>>>
>>> This demonstration of Mono-add-Plump failure doesn't apply to MAMPO, but that method would also fail Irrelevant Ballots Independence. It may be far less bad.
>>> https://electowiki.org/wiki/Majority_Approval,_Minimum_Pairwise_Opposition
>>>
>>> Procedure
>>>
>>> The voter submits a ranking of the candidates. The candidates explicitly ranked are considered *approved* by that voter.
>>>
>>> The *score* for candidate *X* against candidate *Y* is equal to the number of voters ranking *X* above *Y*. The *max score* of candidate *X* is the largest score of any other candidate against *X*.
>>>
>>> If nobody is approved by more than half of the voters, then the candidate approved by the most voters is elected.
>>>
>>> Otherwise, the candidate with the lowest max score, who is approved by more than half of the voters, is elected.
>>>
>>>
>>> Chris B.
>>>
>>>
>>>
>>> On 2/06/2024 7:23 am, Kevin Venzke wrote:
>>>
>>> Hi all,
>>>
>>> When I test for SFC compliance the rule on cast votes is that if there is no
>>> majority over A, and A has a majority over B, then B can't win.
>>>
>>> This is kind of a flip side of MD / SDSC because, if you were forced to explain MD
>>> in terms of a graph of majority-strength defeats, it would say that if A has a
>>> majority over B and B doesn't have a majority over anyone, then B can't win.
>>>
>>> MD basically says that if there are two frontrunners and everyone truncates their
>>> less liked frontrunner, then the worse frontrunner won't win. If this property
>>> doesn't hold, it means the majority has done something to stop the method from
>>> "seeing" their majority, which is surely that they ranked other candidates above
>>> the preferred frontrunner. So MD is mostly about compromise incentive.
>>>
>>> SFC is probably going to be about truncation. When a method fails it, most likely
>>> it's because the majority gave the election away to a less liked compromise choice.
>>> For example:
>>>
>>> 20 C>A>B
>>> 35 A>B
>>> 5 B
>>> 40 D
>>>
>>> Here B is the implicit approval winner, but by SFC B should not win, because it
>>> means it was not safe for the A voters to rank B.
>>>
>>> I would not like to see SFC as totally obsolete, since it was one of the motivating
>>> criteria (along with MD and weak FBC) for my methods MDDA and MAMPO :)
>>>
>>> Kevinvotingmethods.net
>>>
>>>
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