[EM] What are some simple methods that accomplish the following conditions?

[C.Benham]

Kevin,

When I wrote my last message I was probably under-estimating the chance 
of the burial strategy
succeeding even when all those who prefer the target candidate to the 
buriers' candidate place
their approval cutoffs between them.  So I only had in mind the scenario 
where two big factions
both use (rank but not approve) the same presumed sure loser to bury 
against each other.

You didn't address my question as how big you think that fraction should 
be. Forest suggested it
should only be 1/2.

I still think that the chance that burial strategy will either succeed 
or disastrously backfire is very
small.  My idea is to have the runoff triggered only in very bad 
situations which might otherwise
have people calling for the method to be scrapped, so that buriers don't 
often have an easy option
to repair the damage caused by their strategy backfiring.

> If the voted CW turns out to not be your candidate, you would have had 
> a second chance at the win by voting instead to deny CW status to that 
> candidate.

Only if the voted CW is less than half as approved as the AW and only if 
the AW is your candidate, plus you have the "penalty" of having to vote 
again.

Chris Benham

On 12/06/2019 10:00 am, Kevin Venzke wrote:
> Hi Chris,
>
> Le dimanche 9 juin 2019 à 21:20:34 UTC−5, C.Benham 
> <cbenham at adam.com.au> a écrit :
> >Kevin,
> >
> >So to be clear the possible "complaint" some voters might have (and 
> you think we should take seriously) is "We lied
> >and the voting method
> >(instead of somehow reading our minds) believed us".
> A burial strategy has two scenarios that could give rise to a 
> complaint. One is where burial succeeds. In that case the voters who 
> complain aren't the ones who buried. The other scenario is where 
> burial backfires. In that case it is, I guess, possible that actually 
> *all* voters were using burial. So you may argue that they don't have 
> a valid complaint. But implicit to my concerns is the premise that the 
> voters are behaving rationally under the incentives of the method. If 
> a method produces arbitrary results given rational voters then it will 
> be hard to retain it. I think if it happens even once it will be a 
> problem.
>
> >
> >So therefore it is good to have a less expressive ballot because that 
> reduces the voter's opportunities to tell stupid
> >lies and if the method
> >is simple enough then maybe also the temptation for them to do so.
>
> You're making it sound as though a simpler ballot just tricks people 
> into not lying. Expressiveness isn't the point. The reason three-slot 
> C//A (or implicit etc.) deters burial is that there is far more risk 
> in trying it. It is highly likely to backfire no matter what other 
> voters do. "Low expressiveness" of the ballot doesn't guarantee this 
> and isn't a prerequisite for it either.
>
> >
> >But I've thought of a patch to address your issue.  We could have a 
> rule which says that if the winner's approval
> >score is below some fixed
> >fraction of that of the most approved candidate, then a second-round 
> runoff is triggered between those two
> >candidates.  What do you
> >think of that? What do you think that fraction should be?
>
> I think there is some confusion here between what my issue is, and the 
> voter complaints you asked about. While I think voters will be unhappy 
> with a ruined election, ruining it is what reduces the burial 
> incentive. If the risk outweighs the benefit then people won't do it. 
> (That's an assumption.) This patch seems to remove the risk while 
> leaving the benefit unchanged. Burial will ultimately do nothing, 
> except to sometimes move the win from the CW to the AW. But that makes 
> the potential gain even clearer: If the voted CW turns out to not be 
> your candidate, you would have had a second chance at the win by 
> voting instead to deny CW status to that candidate. If the voted CW 
> *is* your candidate, then you're no worse off for using burial.
>
> Kevin
>
> On 10/06/2019 9:57 am, Kevin Venzke wrote:
> Hi Chris,
>
>> >>I don't think it's ideal if burying X under Y (both disapproved) 
>> can only backfire when Y is made the CW.
>> >>
> >Why is that?  
>
> Because I think if voters decide to attempt to prevent another 
> candidate from being CW, via insincerity, there should be risks to 
> doing that. Of course there is already some risk. But if you "knew" 
> that a given candidate had no chance of being CW then there would be 
> nothing to lose in using that candidate in a burial strategy.
>
> >The post-election complaint (by any of the voters) would be .. what?
>
> For either a successful burial strategy, or one that backfires and 
> elects an arbitrary candidate, I think the possible complaints are 
> clear. Maybe someone would argue that a backfiring strategy proves the 
> method's incentives are just fine. But that wouldn't be how I see it. 
> I think if, in actual practice, it ever happens that voters calculate 
> that a strategy is worthwhile, and it completely backfires to the 
> point that everyone would like the results discarded, then that method 
> will probably get repealed.
>
> >
> >If you don't allow voters to rank among their unapproved candidates then arguably you 
> are not even trying to elect the sincere CW.
> >Instead you are just modifying Approval to make it a lot more Condorcet-ish.
>
> Not an unfair statement. If you require voters to have that much 
> expressiveness then you can't use implicit.
>
> To me, the motivation for three-slot C//A(implicit) is partly about 
> burial, partly about method simplicity, partly about ballot 
> simplicity. C//A(explicit) retains 1 of 3. (Arguably slightly less for 
> the Smith version.) Possibly it has its own merits, but they will 
> largely be different ones.
>
> >
> >A lot of voters like relatively expressive ballots. I think that is one of the reasons why 
> Approval seems to be a lot less popular than IRV.
>
> I have no *inherent* complaints about the ballot format of explicit 
> approval plus full ranking.
>
> Kevin
>
>
>
>
> Le jeudi 6 juin 2019 à 21:03:19 UTC−5, C.Benham <cbenham at adam.com.au> 
> <mailto:cbenham at adam.com.au> a écrit :
>
>
> Kevin,
>
>> Specifically should "positional dominance" have the same meaning 
>> whether or not the method has approval in it?
>
> If the voters all choose to approve all the candidates they rank, then 
> yes.  (For a while I was wrongly assuming that Forest's suggested
> default approval was for all ranked-above-bottom candidates, but then 
> I noticed that he specified that it was only for top voted candidates).
>
> One of my tired examples:
>
> 25: A>B
> 26: B>C
> 23: C>A
> 26: C
>
> Assuming all the ranked candidates are approved, C is by far the most 
> approved and the most top-voted candidate.
> Normal Winning Votes (and your idea 2 in this example) elect B.
>
>> I will go easy on these methods over failing MD, because it happens 
>> when some of the majority don't approve their common candidate.
>
> For me this this type of ballot avoids the Minimal Defense versus 
> Chicken Dilemma dilemma, rendering those criteria inapplicable.
>
> 48: A
> 27: B>C
> 25: C
>
> The problem has been that we don't know whether the B>C voters are 
> thinking "I am ranking C because above all I don't want that evil A
> to win" or  "My C>A preference isn't all that strong, and I think that 
> my favourite could well be the sincere CW, and if  C's supporters rank
> B above A then B has a good chance to win. But if they if they create 
> a cycle by truncating I'm not having them steal it".
>
> With the voters able to express explicit approval we no longer have to 
> guess which it is.
>
>> I don't think it's ideal if burying X under Y (both disapproved) can 
>> only backfire when Y is made the CW.
>>
> Why is that?  The post-election complaint (by any of the voters) would 
> be .. what?
>
> If you don't allow voters to rank among their unapproved candidates 
> then arguably you are not even trying to elect the sincere CW.
> Instead you are just modifying Approval to make it a lot more 
> Condorcet-ish.
>
> A lot of voters like relatively expressive ballots. I think that is 
> one of the reasons why Approval seems to be a lot less popular than IRV.
>
> Chris Benham
>
> On 6/06/2019 5:34 pm, Kevin Venzke wrote:
> Hi Chris,
>
> I've been short on time so I don't actually have much thought on any 
> of the methods, even my own.
>
> I suppose Idea 2 is the same as Schwartz-limited MinMax(WV) if nobody 
> submits disapproved rankings. I'm not sure if it makes sense to reject 
> the method over that. Specifically should "positional dominance" have 
> the same meaning whether or not the method has approval in it? As a 
> comparison, I will go easy on these methods over failing MD, because 
> it happens when some of the majority don't approve their common candidate.
>
> I would have liked to simplify Idea 2, but actually Forest's eventual 
> proposal wasn't all that simple either. As I wrote, if you add "elect 
> a CW if there is one" it can become much simpler, so that it isn't 
> really distinct from Idea 1. I actually tried pretty hard to present 
> three "Ideas" in that post, but kept having that problem.
>
> I posted those ideas because I thought Forest posed an interesting 
> challenge, and I thought I perceived that he was trying to fix a 
> problem with CD. That said, I am not a fan of 
> Smith//Approval(explicit). If all these methods are basically the same 
> then I probably won't end up liking any of them. I don't think it's 
> ideal if burying X under Y (both disapproved) can only backfire when Y 
> is made the CW.
>
> Kevin
>
>
> Le mercredi 5 juin 2019 à 21:26:23 UTC−5, C.Benham 
> <cbenham at adam.com.au> <mailto:cbenham at adam.com.au> a écrit :
>
> Kevin,
>
> I didn't comment earlier on your "idea 2".
>
> If there no "disapproved rankings" (i.e. if the voters all approve the 
> candidates they rank above bottom),
> then your suggested method is simply normal  Winning Votes, which I 
> don't like because the winner can
> be uncovered and positionally dominant or pairwise-beaten and 
> positionally dominated by a single other
> candidate.
>
> On top of that I don't think it really fills the bill as "simple".  
> Approval Margins (using Sort or Smith//MinMax
> or equivalent or almost equivalent algorithm) would be no more complex 
> and in my opinion would be better.
>
> I would also prefer the still more simple Smith//Approval.
>
> What did you think of my suggestion for a way to implement your idea 1?
>
>
> Chris
>


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