[EM] SARA voting: easier-to-describe MAS

[Michael Ossipoff]

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>
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> 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> 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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>> info
>>
>>
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