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

[Michael Ossipoff]

Ok, maybe you're right, &  maybe, among Smith methods, Smith//Approval does
the best, in terms of choosing from the most top-sets.

In fact maybe, compared to other rank methods in general,  it does best by
that standard.

I was comparing it to other rank-methods by a standard based on CWs (only
indirectly related to top-sets), ignoring the Approval in Smith//Approval.

Thanks for pointing that out. ...pointing out something I'd missed.

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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>
>
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