Re: [EM] MMPO(IA>MPO) (was IA/MMPO)
Hi Forest, I should say, it seems I went too far in describing the "potential approval winner set" idea. That idea is only descriptive for the ordinary Plurality criterion that is based on strict first preferences (because you can assume that the approvals for those candidates would still be there under an Approval election). While the "IA>=MPO" criterion is (I would say) sound, it is a bit harder to defend along the same lines, because the MPO could come from a candidate ranked relatively low. > De : Forest Simmons >thanks for the insights and suggestions. It's kind of you to suggest my name, >Jameson, but I would rather something more descriptive similar to "the >potential approval winner set" of Chris and Kevin or more public relations >friendly like the Democratically Acceptable Set. My original motivation (that >eventually led to IA/MPO as an approximate solution) was to find a candidate >most likely to win two approval elections in a row (going into the second >election as front runner) without a change in sincere voter preferences, but >with an opportunity to adjust their ballot approval cutoffs. > And also maintain monotonocity and/or FBC, I suppose? Otherwise, it wouldn't be so hard. > >Personally, I still prefer IA-MPO over MMPO[IA>=MPO] because of the superior >participation properties, but I recognize the importance of the Majority >Criterion in public proposals. Ironically, in reality Approval satisfies the >ballot version of the Majority Criterion, while IA-MPO does not, yet in the >face of disinformation or other common sources of uncertainty IA-MPO is at >least as likely to elect the actual majority favorite as Appoval is. > Well personally, I would want to keep the IAMPO name but apply it to MMPO[IA>=MPO] since the latter is not pronounceable. Or else maybe a name for the set is really needed. It's up to you of course. But, I don't really like marketing-oriented names like DMC. I feel like you'll end up in situations where you have to answer e.g. "what is DMC and why is it good" while never using the D, the M, or the C in your answer because they're not really that relevant to the concept. Too bad, that appealing yet descriptive names are so hard to find. Kevin Venzke Election-Methods mailing list - see http://electorama.com/em for list info
[EM] Chicken Dilemma--To whom is it a problem?
Someone at EM (when he was more honest?) said that the chicken dilemma is voting-systems' most intractable problem. But others here say or imply that it won't be a problem. Sure, if you're a committed advocate of Beatpath, and if Beatpath is vulnerable to chicken dilemma, then you're going to have strong incentive to believe that there won't be a chicken dilemma, even with vulnerable methods. I mean, Beatpath and RP are so perfect when FBC isn't needed, and when there isn't a chicken dilemma, you oh so strongly need to believe that ther won't be one. Now, I'm not saying that there are no groups that, if they were a mutual majority, wouldn't have chicken dilemma (but I' not saying that that there are). What we surely can all agree on is that at least _some_ groups of people would have chicken dilemma. ...due to dishonesty, fickleness, distrust, antagonism, perceived enmity, etc. Ok, that's enough to say that there will be chicken dilemma in our public political elections. So much for that question. I'll even be more specific. I've been told that I shouldn't be specific. The progressives, as a group, have plenty of mutuial antagonism, animosty, anger, distrust, and perceived enmity among eachother, as a group. So, say we were using a voting system vulnerable to chicken dilemma, and say the progressves, together, have a mutual majority. Would they be able to benefit from their mutual majority? They woudn't have a chance. ...unless they used good anti-defection strategy. That's a lot to ask. So it's for the progressives that I want freedom from chicken dilemma. Oh, what's that? We should't say that? Yeah, I've been criticized for emphsizing voting system reform for progressives, instead of for Democrats and Republicans too :-) You want to assure Democrats that a (or your?) voting system reform would help the Democrats, and you want to assure the Republicans that it would help the Republicans. Well, feel free to try that scam if you want to, if lying doesn't bother your conscience. With better voting system, the Republocrats would be all finished. In fact, without the Republocrats already having voted out of office, there won't ever _be_ a better voting system. So, will getting rid of the chicken dilemma benefit anyone other than the progressives? Frankly, my dear, I don't give a damn. Michael Ossipoff Election-Methods mailing list - see http://electorama.com/em for list info
Re: [EM] MMPO(IA>MPO) (was IA/MMPO)
OK, then could we call it the "First-level-strategic Approval Winner set" or the 1SAW set for short? I suspect better names are possible, but I can't think of one. As an aside: I think exploring good ranked methods like this is worthwhile from a theoretical point of view. But from a practical perspective, I suspect that this kind of thing will always be too complicated to explain to voters. That's why I prefer things like MAV (using a Bucklin-like motivation) or SODA (whose rules, though they aren't simple, at least "make sense" and give each candidate a clear approval score at each step, with the highest final approval winning). Second aside: a while back I gave an example which purported to show that SODA was not monotonic, but I missed a (rationally dominant) way to get the right result on that example within the SODA framework; so at the present, I strongly believe that SODA is (rationally) monotonic after all, and in fact I'm working on a proof. Jameson. 2013/10/14 Forest Simmons > Kevin and Jameson, > > thanks for the insights and suggestions. It's kind of you to suggest my > name, Jameson, but I would rather something more descriptive similar to > "the potential approval winner set" of Chris and Kevin or more public > relations friendly like the Democratically Acceptable Set. My original > motivation (that eventually led to IA/MPO as an approximate solution) was > to find a candidate most likely to win two approval elections in a row > (going into the second election as front runner) without a change in > sincere voter preferences, but with an opportunity to adjust their ballot > approval cutoffs. > > Remember when we were looking at DMC from various points of view? One was > to think of the DMC winner as the beats all candidate relative to the set P > of candidates that were not doubly defeated, i.e. not defeated both > pairwise and in approval by some other candidate. In other words each > member of P defeats pairwise every candidate with greater approval. The > approval winner, the DMC winner, the Smith\\Approval winner, and the lowest > approval candidate that covers all higher approval candidates, etc. are > some of the members of P. > > Also, no member of P has greater MPO than IA (assuming we are talking > about Implicit Approval in the definition of P). So every member of P has > a fair chance at winning MMPO[IA>=MPO], although the winner is not > guaranteed to come from P. The main advantage of MMPO[IA>=MPO] over > MMPO(P) is that the former satisfies the FBC while the latter does not. > > For the record, here's why the entire set P survives step one: > > Let X be a member of P, and let Y be a candidate whose pairwise opposition > against X is maximal, i.e. is MPO(X). If IA(Y) is greater than IA(X), then > (by definition of P) X beats Y pairwise, and so X is ranked above Y more > than MPO(X), the number of ballots on which Y is ranked over X. In other > words, in this case X is ranked on more ballots than the number MPO(X), i.e > IA(X)>MPO(X). If IA(Y) is no greater than IA(X), then MPO(X) is no greater > than IA(X), since MPO(X) is no greater than IA(Y). Since the cases are > exhaustive and in neither case is MPO(X) greater than IA(X) we are done. > > Personally, I still prefer IA-MPO over MMPO[IA>=MPO] because of the > superior participation properties, but I recognize the importance of the > Majority Criterion in public proposals. Ironically, in reality Approval > satisfies the ballot version of the Majority Criterion, while IA-MPO does > not, yet in the face of disinformation or other common sources of > uncertainty IA-MPO is at least as likely to elect the actual majority > favorite as Appoval is. > > We need Chris to search for the chinks in the armor of these methods. > Where are you Chris? > > Forest > > > > > > > > > On Sun, Oct 13, 2013 at 10:02 AM, Kevin Venzke wrote: > >> Hi Forest, >> >> I read your first message: At first glance I think the new method (elect >> the MMPO winner among those candidates whose IA>=MPO) is good. It doesn't >> seem to gain SFC, which is actually reassuring, that this might be a >> substantially different method from others. It seems like it is mainly an >> MMPO tweak (since the MMPO winner usually will not be disqualified) with >> corrections for Plurality and SDSC/MD. >> >> Off the top of my head I can't see that anything is happening that would >> break FBC. >> >> >> > De : Forest Simmons >> >À : Kevin Venzke >> >Cc : em >> >Envoyé le : Samedi 12 octobre 2013 13h58 >> >Objet : Re: MMPO(IA>MPO) (was IA/MMPO) >> > >> > >> >Kevin, >> > >> >In the first step of the variant method MMPO[IA >= MPO] (which, as the >> name suggests, elects the MMPO candidate from among those having at least >> as much Implicit Approval as Max Pairwise Opposition) all candidates with >> greater MPO than IA are eliminated. >> > >> >I have already shown that this step does not eliminate the IA winner. >> Now I show that this step does not eliminate the Sm
Re: [EM] MMPO(IA>MPO) (was IA/MMPO)
Kevin and Jameson, thanks for the insights and suggestions. It's kind of you to suggest my name, Jameson, but I would rather something more descriptive similar to "the potential approval winner set" of Chris and Kevin or more public relations friendly like the Democratically Acceptable Set. My original motivation (that eventually led to IA/MPO as an approximate solution) was to find a candidate most likely to win two approval elections in a row (going into the second election as front runner) without a change in sincere voter preferences, but with an opportunity to adjust their ballot approval cutoffs. Remember when we were looking at DMC from various points of view? One was to think of the DMC winner as the beats all candidate relative to the set P of candidates that were not doubly defeated, i.e. not defeated both pairwise and in approval by some other candidate. In other words each member of P defeats pairwise every candidate with greater approval. The approval winner, the DMC winner, the Smith\\Approval winner, and the lowest approval candidate that covers all higher approval candidates, etc. are some of the members of P. Also, no member of P has greater MPO than IA (assuming we are talking about Implicit Approval in the definition of P). So every member of P has a fair chance at winning MMPO[IA>=MPO], although the winner is not guaranteed to come from P. The main advantage of MMPO[IA>=MPO] over MMPO(P) is that the former satisfies the FBC while the latter does not. For the record, here's why the entire set P survives step one: Let X be a member of P, and let Y be a candidate whose pairwise opposition against X is maximal, i.e. is MPO(X). If IA(Y) is greater than IA(X), then (by definition of P) X beats Y pairwise, and so X is ranked above Y more than MPO(X), the number of ballots on which Y is ranked over X. In other words, in this case X is ranked on more ballots than the number MPO(X), i.e IA(X)>MPO(X). If IA(Y) is no greater than IA(X), then MPO(X) is no greater than IA(X), since MPO(X) is no greater than IA(Y). Since the cases are exhaustive and in neither case is MPO(X) greater than IA(X) we are done. Personally, I still prefer IA-MPO over MMPO[IA>=MPO] because of the superior participation properties, but I recognize the importance of the Majority Criterion in public proposals. Ironically, in reality Approval satisfies the ballot version of the Majority Criterion, while IA-MPO does not, yet in the face of disinformation or other common sources of uncertainty IA-MPO is at least as likely to elect the actual majority favorite as Appoval is. We need Chris to search for the chinks in the armor of these methods. Where are you Chris? Forest On Sun, Oct 13, 2013 at 10:02 AM, Kevin Venzke wrote: > Hi Forest, > > I read your first message: At first glance I think the new method (elect > the MMPO winner among those candidates whose IA>=MPO) is good. It doesn't > seem to gain SFC, which is actually reassuring, that this might be a > substantially different method from others. It seems like it is mainly an > MMPO tweak (since the MMPO winner usually will not be disqualified) with > corrections for Plurality and SDSC/MD. > > Off the top of my head I can't see that anything is happening that would > break FBC. > > > > De : Forest Simmons > >À : Kevin Venzke > >Cc : em > >Envoyé le : Samedi 12 octobre 2013 13h58 > >Objet : Re: MMPO(IA>MPO) (was IA/MMPO) > > > > > >Kevin, > > > >In the first step of the variant method MMPO[IA >= MPO] (which, as the > name suggests, elects the MMPO candidate from among those having at least > as much Implicit Approval as Max Pairwise Opposition) all candidates with > greater MPO than IA are eliminated. > > > >I have already shown that this step does not eliminate the IA winner. > Now I show that this step does not eliminate the Smith\\IA winner either: > > > >Let X be the Smith candidate with max Implicit Approval, IA(X), and let Y > be a candidate that is ranked above X on MPO(X) ballots. There are two > cases to consider (i) Y is also a member of Smith, and (ii) Y is not a > member of Smith. > > > > > >In both cases we have MPO(X) is no greater than IA(Y), because Y is > ranked on every ballot expressing opposition of Y over X. > > > > > >Additionally in the first case IA(Y) is no greater than IA(X) because X > is the Smith\\IA winner. So in this case MPO(X) is no greater than IA(X) > by the transitive property of "no greater than." > > > > > >In the second case, X beats Y pairwise since X is in Smith but Y is not. > This entails that X is ranked above Y on more ballots than Y is ranked > above X. In other words, X is ranked on more ballots than MPO(X). > Therefore IA(X) > MPO(X), > > > > > >In sum, in neither case is the Smith\\IA winner X eliminated by the first > step in the method MMPO[IA>=MPO]. > > > > > >We see as a corollary that step one never eliminates a (ballot) Condorcet > Winner. In particular, it does not eliminate a (ballot) m
[EM] Properties & their justification. Conditions.
For votinig-systems, properties are really important. That should be obvious. What else is important in choosing among voting-systems? At such time as any voting-system may be proposed to the public, it would obviously be necessary to tell its properties. Especiallly its purported advantages in terms of properties. ...what properties make it better than other methods. The importance of that can't be overstressed. But what's really been missing from EM discussion has been the _justification_ of claims about the desirability of properties. You know, that must really be the basis of voting-system comparisons.It has to start with justifications or explanations regarding claims about the desirability of properies. That's been missing at EM. But it isn't the only thing that's been missing at EM (aside from good manners): Methods are proposed and compared at EM, without any mention of the conditions for which the methods are proposed or offered. I've specified and defined two kinds of conditions: Current conditions, and Green scenario. I've defined them briefly in my post before this one, but I've defined them and explained them more thorougly in previous posts. That's for public political elections. For organizational elections and polls, I've posted about other conditions-distinctiona as well. Conditions make all the difference, regarding the need for particular propertes. Comparison of method-merits, based on properties, and the justification of properties' desirability, really must be based on a specification of the conditions for which those properties are important, and for which those methods are recommended. These considerations have been present in my comments, discussion and recomendations Michael Ossipoff Election-Methods mailing list - see http://electorama.com/em for list info
[EM] Ranking of Greeen-scenario methods.
Merit ranking of methods, for the Green scenario: 1. Woodall 2. Benham 3. AIRV (defined below) 4. IRV 5. Beatpath, RP, Approval, Score AIRV (Approval-IRV): Same as IRV, except allows equal ranking (at least for 1st place), and all the candidates currently sharing top position in a ranking are regarded as topping that ranking. [end of AIRV definition] As for why Woodall and Benham are ranked highest, and why Woodall is above Benham, it's for reasons stated in my previous post, and others before that. AIRV is the next best thing. Though IRV's failure of the Condorcet Criterion (CC) can make a strategy situation, sincere voting can still be justified. The chicken dilemma, to which Beatpath & RP are subject, can't be ignored. When it exists, strategy is needed. The chicken dilemma is worse than IRV's CC failure. Hence Beatpath's and RP's rank-postion below that of IRV. Approval, Score, Beatpath & RP are ranked equally at the bottom of that list of methods (but above those not ranked), because FBC, though not needed in the Green scenario, never really stops being somewhat desirable. If there were still a favorite-burial incentive for Beatpath, then Approval would be better than Beatpath. If there were no chicken dilemma, Beatpath & RP would probably be the very best. ...but chicken dilemma will be common in public political elections. I once wrote to some Beatpath-using organizations, offering Woodall and Benham (but especially Schwartz-Woodall), because of freedom from chicken dilemma. I was told that their organizations didn't have chicken dilemma. That's good. If they don't have the chicken dilemma, then Beatpath/CSSD is probably the best choice for those organizations. That gives me reason to be glad that I introduced wv Condorcet, pointed out some advantages of it, and offered Beatpath/CSSD to organizations. Comparing Beatpath, SSD, and RP: Beatpath and CSSD are equivalent. In public political elections, with many voters and no pairwise ties, Beatpath, CSSD and SSD are equivalent. In comparison to Ranked-Pairs (RP), Beatpath is easier to program, and somewhat faster to compute (though computation time for Beatpath or RP will be negligible with modern computers). But RP is incomparably more briefly-defined, and therefore easier to propose. And its rule-justification is clearer and more obvious. As a proposal for public elecions, the considerations in the paragraph before this one are more important. But, for many organizations, the considerations in the paragraph before that are more important, explaining why it is Beatpath/CSSD that those organizations use. A detail: It is said that CSSD stands for Cloneproof SSD. And it now does, and that's fine. But when I named CSSD, I meant "Committee SSD", because in small committees, where there can be pairwise-ties, that's where CSSD and SSD can differ, and where CSSD has an advantage over SSD. Anyway, Beatpath/CSSD, SSD, and RP, are disqualified, by the chicken dilemma, from public political elections, though they're probably the best for organizations that are sure that they don't have chicken dilemma. Election-Methods mailing list - see http://electorama.com/em for list info
