[EM] Trying to have CD, protect strong top-set, and protect middle candidates too
C.Benham
cbenham at adam.com.au
Fri Nov 18 21:18:31 PST 2016
On 11/19/2016 3:14 AM, Michael Ossipoff wrote:
> If the more embarrassing Mono-Raise failure doesn't give IRV any
> acceptance or enactment problem, then why should the less embarrassing
> Mono-Add-Plump failure of MDDTR give MDDTR an acceptance or enactment
> problem?
Because what you consider more or less "embarrassing" I am sure isn't in
accord with what most people would find unacceptably ridiculous.
> With MDDTR, if your plump for X makes X lose, it's because you added a
> ballot. It has nothing whatsoever to do with the fact that you voted
> favorably to X.
That's right. "You" should have found some way to vote for X without
adding a ballot. Unfortunately removing someone else's ballot when you
are in the
polling station is usually impossible or legally risky.
> Anyway, if IRV is so widely used and successful, then why would
> nonmonotonicity be a problem for MDDTR?
Because IRV has a traditional and (for many) intuitive algorithm, and a
solid "maximal" set of criterion compliances and MDDTR doesn't.
Earlier you attempted to ridicule my observation that MDDTR fails
Irrelevant Ballots Independence by suggesting that might indirectly
motivate a higher
turnout. Well, just as some might have an interest in promoting that
(for voters who'll ignore the competitive/viable candidates) so as to
wash away
an otherwise likely majority-defeat disqualification so would opposed
forces have an interest in doing the opposite.
In fact you could have post-election recriminations reminiscent of those
that were aimed at Nader and those who voted for him supposedly allowing
Bush to
win a few years ago. "Those idiots weren't even really interested in who
won, why didn't they just stay home?!" could be the lament.
Just the knowledge that a failure of Mono-add-Plump is theoretically
possible could reduce people's enthusiasm for voting and make it more
likely that those who like to vote by just plumping for their favourite
will stay home.
Whereas IRV doesn't just meet mono-add-plump. It also meet Mono-add-Top.
> C: Failing mono-add-plump is as stupid as a quasi-"intelligent" device
> can be, in a pure and starkly obvious way, and with the lamest
> possible excuse.
>
> The algorithm/device decides that X should win, and then receives some
> more ballots that contain nothing whatsoever but the pure and simple
> message:
> "You are right! X should win" and responds with the bizarre
> malfunction "I've changed my mind, Y should win" and offers the
> nonsensical excuse "Hey those
> extra ballots didn't just say that X should win. They also increased
> the total number of ballots!".
>
>
>> C: What (arguably) desirable properties (or criterion compliances)
>> are incompatible with meeting Mono-add-Plump?
>>
>> Mike: FBC, CD, & wv-like strategy are evidently require failing
>> Mono-Add-Plump, or having MMPO's Hitler-with-2-votes problem.
>>
>> With MDDTR, the price of FBC, CD & wv-like strategy is Mono-Add-Plump.
>
> C: There are methods that meet FBC and CD and mono-add-plump. So your
> proposition boils down to saying that it's worth giving up compliance
> with
> mono-add-plump just to gain "wv-like strategy".
Chris Benham
On 11/19/2016 3:14 AM, Michael Ossipoff wrote:
> I don't mean that IRV isn't ok. IRV's Mono-Raise failure doesn't
> bother me.
> Neither does MDDTR's Mono-Add-Plump failure.
>
> Voting's purpose is probabilistic anyway. You vote to improve the
> probability of a better outcome. The possible nonmonotonicity of IRV
> & MDDTR doesn't invalidate that.
>
> My point, in asking about when you make someone lose by raising hir
> from last place to 1st place, was just that IRV is popular and widely
> used. It's been used in Australia for a long time, and it's used in a
> fair number of cities in this country. ...and now has been adopted by
> the state of Maine.
>
> ...in spite of its Mono-Raise failure.
>
> If the more embarrassing Mono-Raise failure doesn't give IRV any
> acceptance or enactment problem, then why should the less embarrassing
> Mono-Add-Plump failure of MDDTR give MDDTR an acceptance or enactment
> problem?
>
> There of course have been objections to IRV, some valid, some not. But
> I haven't heard any of the IRV critics in the various cities complain
> about its nonmonotonicity. They object to implementation complexity.
> They invalidly claim voting complexity. They invalidly complain
> because supposedly voting is supposed to be by Plurality. They
> repealed IRV in Burlington because of the elimination of a CWv. But
> none of the complaints that I've heard, in cities using it or
> considering IRV, have been about its nonmonotonicity.
>
> Why I say that Mono-Raise failure is more embarrassing:
>
> With MDDTR, if your plump for X makes X lose, it's because you added a
> ballot. It has nothing whatsoever to do with the fact that you voted
> favorably to X.
>
> With IRV, if raising X from bottom to top makes X lose, then X lost
> for no other reason than because you helped hir more.
>
> There are 2 kinds of nonmonotonicity:
>
> Did you make X lose _in spite of_ voting favorably for hir?
>
> or
>
> Did you make X lose _because_ you voted hir more favorably?
>
> Of those 2 kinds of nonmonotonicity the 2nd one is more of an
> embarrassment to the method. There, the method is more directly acting
> oppositely to your action.
>
> Maybe it could be said that the 2nd kind of nonmonotonicity is twice
> as embarrassing to the voting-system.
>
> Anyway, if IRV is so widely used and successful, then why would
> nonmonotonicity be a problem for MDDTR?
>
> I now feel that IRV's (mitigated) problem isn't an unusually high
> price for CD, isn't more than the "going rate" for CD. IRV & its
> derivatives are at the top of my ranking of method-merit for
> electorates who want &/or need ranking.
>
> Michael Ossipoff
>
>
>
>
>
>
>
> On Fri, Nov 18, 2016 at 1:23 AM, Michael Ossipoff
> <email9648742 at gmail.com <mailto:email9648742 at gmail.com>> wrote:
>
> Forest--
>
> You wrote:
>
>
> But MAI still fails FBC.
>
>
> Failing both FBC & CD isn't good.
>
>
> So to me the best proposal is ICA with default approval cutoff
> at truncation to help punish burial and truncation with an
> option to raise the cutoff to withstand a CD attack.
>
>
> But buriers or truncators could raise that approval cutoff too.
> Someone could bury X under Z without having to approve Z. That
> loses the deterrence that would exist if that burier had to
> approve Z in order to rank hir over someone, as would be so if
> ranking is counted as approval.
>
> So CD still comes at the cost of a lot less protection against
> burial, or, in ICT's case, trunction too.
>
> But that just means that it isn't _better_ than MDDTR in that
> regard. It doesn't mean that it's worse.
>
> And it doesn't have Mono-Add-Plump failure.
>
> So, the method has CD as MDDTR does, and trades
> truncation-proofness for Mono-Add-Plump.
>
> I value strategy protections more than embarrassment criteria.
> (But I realize that proposal-opponents can use embarrassment
> criteria criticisms, and that proponents aren't likely to be able
> to afford as much media time, to answer the criticisms.)
>
> [Replying farther down] :
>
>
>
> Here's my version (slightly different from the original):
>
> Candidate X strongly beats candidate Y iff
>
> the number of ballots on which X is ranked over Y is greater than
>
> the number of ballots on which Y is _/*ranked*/_ equal to or
> greater than Y.
>
> [Note Y is not ranked equal to X if Y is not ranked.]
>
> If not all of the candidates are strongly beaten, disqualify
> all of the ones who are.
>
> Elect the most approved qualified candidate.
>
> I think that this method has all of the good properties of
> MDDA with mono-add-plump to boot.
>
>
> I've only had a preliminary look at it, but it seems to me, right
> now, that the separate approval-cutoff that the voter can raise
> from the default spoils protection from burial & truncation.
>
>
> You wrote:
>
> We still need to explore MDDA with the half power truncation
> rule, since it would also satisfy mono-add-plump if I am not
> mistaken.
>
>
> Yes, it seems to me that a 1/2 power-truncation would get rid of
> the Mono-Add-Plump failure. If, by not ranking a certain 2
> candidates, you give them each at least half of a vote against
> eachother, that would bring Mono-Add-Plump compliance, it seems to me.
>
> So maybe it would avoid criticism of MDDA.
>
> But, if used with MDDTR, it would spoil CD.
>
> You wrote:
>
>
>
> I agree with Chris Benham that mono-add-plump failure would be
> fatal in a public proposal.
>
>
> What if you're going to rank X last in your ranking. With all the
> ballots, including yours, X will win. But then you move X to 1st
> place in your ranking, and that makes X lose.
>
> Would that be ok?
>
> Michael Ossipoff
>
>
> On Thu, Nov 17, 2016 at 2:12 PM, Michael Ossipoff
> <email9648742 at gmail.com <mailto:email9648742 at gmail.com>> wrote:
>
> I meant to ask: Did you say that MTRI doesn't pass FBC?
> How does FBC failure happen? In return for FBC, it should
> beat MDDTR at vulnerability to burial, and not be
> vulnerable to truncation.
>
> Anyway, anything you can tell me about the properties
> comparison between MTRI & MDDTR would be helpful.
>
> MIchael Ossipoff
>
> On Thu, Nov 17, 2016 at 5:05 PM, Michael Ossipoff
> <email9648742 at gmail.com <mailto:email9648742 at gmail.com>>
> wrote:
>
> For this method, MTRI, the procedural definition is
> more understandable than the recursive definition
> (though the recursive definition's brevity could be
> useful).
>
> So this is what I understand MTRI's procedural
> definition to be:
>
> 1. Order the candidates by their top-count score, with
> higher scores at top.
>
> 2. Switch the lowest pair of adjacent candidates whose
> lower candidate pair-beats the higher one.
>
> Repeat till there are no more pairs to switch. The
> highest candidate in the order at that time wins.
>
> -----------------------------------------------
>
> As a CD rank method, this method is a competitor of
> MDDTR. What are the property differences between MTRI
> & MDDTR?
>
> In particular, how does MTRI compare with MDDTR in
> regards to protection of a CWs against truncation &
> burial?
>
> Michael Ossipoff
>
>
> On Thu, Nov 17, 2016 at 2:55 PM, Forest Simmons
> <fsimmons at pcc.edu <mailto:fsimmons at pcc.edu>> wrote:
>
> On Thu, Nov 17, 2016 at 10:54 AM, Michael Ossipoff
> <email9648742 at gmail.com
> <mailto:email9648742 at gmail.com>> wrote:
>
> But wouldn't Smith//Approval, with approval
> cutoffs in the rankings, share MDDTR's
> burial-vullnerability?
>
> ...with, additionally, vulnerability to
> truncation, which MDDTR _doesn't_ have?
>
> And Smith//Approval trades MDDTR's FBC for
> Smith, which I consider an unfavorable trade.
>
>
> Perhaps make truncation the default approval
> cutoff, but let voters move it higher as an option:
>
> 45 C
> 30 A>B or A>>B
> 25 B
>
> Voting A>>B would be the chicken defense (where
> sincere is 25 B>A).
>
> Voting A>B would be the truncation defense (where
> sincere is 45 C>B).
>
> With this option, MDDA would be an FBC compliant
> method that is truncation and burial resistant as
> well as quasi CD compliant.
>
> Is there a way to modify MDDA to make it satisfy
> mono-add-plump?
>
> How about incorporating some form of power
> truncation. When you plump X and reduce the
> majority victory of Y over Z to a sub-majority, it
> would revert to a majority if you counted the
> common truncation of Y and Z against each other as
> even half a point.
>
> Btw, in case you didn't see it, one of my new
> favorite non-FBC methods is Most Approved
> Immune(MAI): Elect the most approved immune candidate.
>
> This means elect the most approved candidate X
> that is unbeaten pairwise by the candidate that
> would win (recursively) if the method were applied
> to the same ballot set with X disqualified or
> withdrawn.
>
> It is the simplest approval based rank method that
> confers immunity from second place complaints on
> its winners.
>
> It is quasi CD compliant if voters can specify
> their approval cutoffs above the truncation level
> when they want to.
>
> A top rank version of this method is fully CD
> compliant:
>
> Elect the Most Top Ranked Immune candidate. (MTRI)
>
> In other words elect the most top ranked candidate
> X that is unbeaten pairwise by the candidate that
> would win (recursively) if the method were applied
> to the same ballot set with X disqualified or
> withdrawn.
>
> Forest
>
>
>
>
>
>
>
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