[EM] SARA voting: easier-to-describe MAS
C.Benham
cbenham at adam.com.au
Tue Oct 25 19:48:16 PDT 2016
You mean "disqualified" like all other Condorcet methods?
Chris Benham
On 10/26/2016 9:05 AM, Michael Ossipoff wrote:
> Oops! Smith//Approval is disqualified by its FBC failure
>
> Michael Ossipoff
>
> On Tue, Oct 25, 2016 at 2:55 PM, Michael Ossipoff
> <email9648742 at gmail.com <mailto:email9648742 at gmail.com>> wrote:
>
> But MMPO's Weak CD remains as an advantage, because the chicken
> dilemma can be a nuisance in Approval.
>
> So MMPO isn't completely ruled out.
>
> Michael Ossipoff
>
> On Oct 25, 2016 9:40 AM, "C.Benham" <cbenham at adam.com.au
> <mailto:cbenham at adam.com.au>> wrote:
>
> On 10/25/2016 4:47 AM, Michael Ossipoff wrote:
>
>> When sincerely-voted Approval chooses differently from
>> Condorcet, it's choosing socially better.
>>
>> (Jameson wrote):
>>
>> But even if they do win under honesty, they will probably
>> lose under "semi-honest offensive strategy" (SHOS) in which
>> the stronger wing truncates the CW to equal-bottom.
>>
>> (endquote)
>>
>> In rank methods, we've been calling that offensive truncation.
>>
>> In Approval, I don't regard it as an offensive strategy at
>> all. In Approval, the middle CWs doesn't need support from
>> both sides, as s/he does in general pairwise-count methods.
>>
>> The larger wing isn't the one that needs the CWs, if you're
>> after the best particular candidate you can get. But you're
>> talking about a strategy problem that shouldn't concern
>> voters in Approval.
>>
>
> Mike,
>
> Given my selection of quotes above, I find your negativity on
> Smith//Approval (very similar to Max Covered Approval) a bit
> inconsistent.
>
> A couple of somewhat relevant questions:
>
> (1)How often is a sincere Condorcet winner who is supported by
> the smallest of three factions of voters the Approval winner?
>
> (2) How often is the Approval winner not in the Smith set?
>
> And so what is wrong with Condorcet//Approval?
>
>> Jameson:-In Condorcet systems, the CW wins under honesty by
>> definition. But under SHOS, any CD-compliant method gets the
>> wrong answer.
>>
>> Mike: No. In wv, a CWs isn't vulnerable to truncation. S/he
>> still wins. ...the right answer in such a method.
>>
>
> But Winning Votes isn't a "CD-compliant method" .
>
> Jameson wrote:
>
>> Support Accept Reject Abstain voting works as follows:
>>
>> * Voters can support, accept, reject, or abstain on each
>> candidate. Default is abstain.
>> * Call a candidate "acceptable" if they are rejected by 50%
>> or less and supported or accepted by over 25%. If any
>> candidates are acceptable, eliminate all who aren't.
>> * Give remaining candidates 2 points for each "support", 1
>> point for each "accept", and half a point for each
>> "abstain". Highest points wins.
>>
>>
> I still hate default being anything other than
> bottom/"reject", and the "25%" figure looks arbitrary.
>
> With the default rule as it is, it looks like the method fails
> Mono-add-Plump.
>
> Say the winner X has a lower point score than some other
> candidate Y that is barely rejected by over 50%. Then adding
> some ballots that do nothing
> but "support" X could raise the 50% threshold enough so that
> now Y is no longer eliminated and wins.
>
> Chris Benham
>
>
>>
>> On Oct 23, 2016 8:21 AM, "Jameson Quinn"
>> <jameson.quinn at gmail.com <mailto:jameson.quinn at gmail.com>> wrote:
>> >
>> > Center squeeze occurs in 3-candidate election when the CW
>> is the plurality loser.
>>
>> So it refers to a special case of the problem of the
>> defensive strategy needed to protect the CWs's win.
>>
>> Certainly, in IRV, Benham, & Woodall, the main problem is
>> when a middle Cws has the smallest faction.
>>
>> And, in other pairwise-count methods, when I test for
>> truncation or burial vulnerability, I use such an example,
>> because it seems more favorable to finding vulnerability.
>>
>> But a CWs can lose without being smallest, and I don't make a
>> distinction about that except that it's part of the
>> problem-examples in IRV, Benham, and Woodall.
>>
>> You wrote:
>>
>> There are different levels of the problem, characterized by
>> the level of strategy necessary for the CW to win:
>>
>> (endquote)
>>
>> Sure. I was saying that with wv strategy, truncation from one
>> side can't take the win from the CWs. ...& that the CWs's
>> voters can deter burial by mere plumping.
>>
>> No need for the non-offensive wing to vote any less than
>> sincerely in methods with wv strategy.
>>
>> As you know, that isn't so with other Condorcet versions or
>> general pairwise-count methods.
>>
>> (You wrote):
>>
>> >
>> > -In systems like IRV or plurality, in order for the CW to
>> win even under honesty, the weaker of the two wings must
>> betray their sincere favorite.
>>
>> (endquote)
>>
>> Well, it isn't so much the size of the wing factions. It's
>> more a matter of which wing candidate is preferred by the
>> CWs's voters.
>>
>> That's why I've been saying that IRV is fine for you if
>> you're majority-favored.
>>
>> If the CWs's voters transfer the other way, then you aren't
>> in a mutual-majority, and then, for you, IRV is then no
>> better than Plurality.
>>
>> Many of us have been explaining that to Rob Richie for the
>> past 30 years or so.
>>
>> > -In systems like approval and score, the CW may or may not
>> win under "honesty" (however defined). Arguably, if they do
>> not, they should not.
>>
>> (endquote)
>>
>> Correct. When sincerely-voted Approval chooses differently
>> from Condorcet, it's choosing socially better.
>>
>> Sure, not choosing the CWs got IRV repealed in Burlington.
>>
>> Not electing the CWs results in a majority who'd prefer a
>> different result.
>>
>> But I think IRV was repealed for more than that:
>>
>> Approval let's people protect the CWs, without
>> favorite-burial, if that were what they want to do. ...and
>> I suggest that it isn't, because electing from your top-set
>> is usually more important than electing the best particular
>> individual candidate you can.
>>
>> CWs protection is more for rank methods, which are about
>> choosing _among_ your top-set, to elect the best particular
>> candidate you can.
>>
>> (But see my earlier post yesterday, about that.)
>>
>> If you have a top-set, then, by definition, electing from it
>> is the important thing.
>>
>> Approve (only) your top-set.
>>
>> (More about that in my post yesterday)
>>
>> But, if it turned out to be really important to avoid having
>> a majority who'd prefer a different result, then that could
>> be a reason for voters in Approval to slightly modify their
>> voting to avoid approving past the expected CWs (CWse).
>> ...though that would lower your Pt.
>>
>> When approving your top-set, you'd just stop short of
>> approving past the CWse.
>>
>> Yesterday, too, I spoke of the possibility of your
>> wing-faction having a social agreement to that effect.
>>
>> What you're saying doesn't contract what I've been saying.
>>
>> (You wrote):
>>
>> But even if they do win under honesty, they will probably
>> lose under "semi-honest offensive strategy" (SHOS) in which
>> the stronger wing truncates the CW to equal-bottom.
>>
>> (endquote)
>>
>> In rank methods, we've been calling that offensive truncation.
>>
>> In Approval, I don't regard it as an offensive strategy at
>> all. In Approval, the middle CWs doesn't need support from
>> both sides, as s/he does in general pairwise-count methods.
>>
>> The larger wing isn't the one that needs the CWs, if you're
>> after the best particular candidate you can get. But you're
>> talking about a strategy problem that shouldn't concern
>> voters in Approval.
>>
>> (You wrote):
>>
>> The defensive strategies that work are for the weaker wing to
>> give the CW near-top score, and/or the CW faction to give the
>> stronger wing near-bottom score.
>>
>> (endquote)
>>
>> Both, if people are trying for the best candidate they can
>> get. Then obviously the smaller wing should support the CWs,
>> and the CWs's voters should plump.
>>
>> But I don't suggest that goal for Approval, for the reasons
>> stated above, & in earlier posts.
>>
>> > -In Condorcet systems, the CW wins under honesty by
>> definition. But under SHOS, any CD-compliant method gets the
>> wrong answer.
>>
>> No. In wv, a CWs isn't vulnerable to truncation. S/he still
>> wins. ...the right answer in such a method.
>>
>> With burial, a potentially successful buial can succeed or
>> fail, depending on whether the CWs's voters plump. Either
>> way, the CWs doesn't win.
>>
>> (You wrote):
>>
>> ; the strategy is effective if the CW faction plumps, and
>> backfires if the CW faction cooperates with the weaker wing.
>> Note that even a strategy backfire here is not in my opinion
>> a "good" result; because the strategy has some chance of
>> winning, it will be sometimes attempted. Strategic backfire
>> is a good thing if it discourages the strategy, but a bad
>> thing if it actually occurs.
>>
>> Yes, that's what makes Condorcet at least a bit questionable.
>> ...especially with the possibility of the perpetual burial
>> fiasco.
>>
>> But it can probably be argued that, with rank methods' goal
>> of getting the best individual candidate you can get, wv
>> strategy improves on Bucklin, because, even if people
>> misjudge who the CWs is, and so hir voters don't plump, the
>> mere threat of plumping could be enough to deter burial,
>> because the would-be buriers don't have better information
>> than the defenders have.
>>
>> > -In most basic Bucklin systems, the CW faction must
>> defensively plump to counteract SHOS.
>>
>> Yes, in Bucklin, if you aren't majority-favored, and if you
>> rank sincerely, and if the CWs's voters don't plump, then
>> that can result in the election of someone in your bottom-set.
>>
>> (You wrote):
>>
>> > -In a system like SARA, in most cases, even if the CW does
>> not defensively plump, the weaker wing can give enough
>> support to the CW to protect them from SHOS, without having
>> to rate them equal-top. (If the CW is only barely a CW, the
>> weak wing may have to rate equal-top for a successful defense
>> in this case. However, I think that very tightly-balanced
>> situations like this are not a large concern.)
>>
>> (endquote)
>>
>> That makes me sit up & take notice, because such an
>> improvement on Bucklin strategy, while keeping FBC, would be
>> major, & could outweigh the lack of CD enough to compete with
>> the best methods.
>>
>> Michael Ossipoff
>>
>>
>
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