On Fri, Oct 12, 2012 at 9:09 PM, Jameson Quinn <[email protected]> wrote: > > > 2012/10/12 Michael Ossipoff <[email protected]> >> >> It's easily fixed. >> >> To the definition, after the line >> >> X beats Y iff (X>Y) + (X=Y)B > (Y>X) + (X=Y)T... >> >> insert: >> >> ...except that two candidates can't beat eachother. If the above line >> would have two candidates beat eachother, then one of them beats the >> other. The one that beats the other is the one who is ranked over the >> other on more ballots than vice-versa. >> > > So the only way this is different from Condorcet...
It doesn't differ from Condorcet. It is a Condorcet method. ...an improved one. Hence the name "Improved Condorcet". Improved Condorcet (including ICT, Symmetrical ICT as I now define it, and the previous Symmetrical ICT that didn't work) differs from unimproved Condorcet in regards to the two terms, in the above-quoted beat-condition, that are not present in unimproved Condorcet. ICT and Symmetrical ICT differ in that ICT doesn't use the "+(X=Y)B" term. To say it in a different way, Improved Condorcet differs from unimproved Condorcet by respecting the preferences, intent and wishes of an equal-top or equal-bottom ranking voter. I've justified that statement here at EM, but upon request I'll repeat the justification. > is if two candidates don't > beat each other in either direction? Not at all. See above, for the difference between improved and unimproved Condorcet.. But the difference between Symmetrical ICT as I define it now, and the previous Symmetrical ICT that didn't work, is in regards to situations where the above-quoted beat-condition says that X and Y both beat eachother. The previous Symmetrical ICT recorded them both as beaten thereby. Symmetrical ICT as I define it now doesn't label both candidates as beaten due to that beat-condition saying that they both beat eachother. Symmetrical ICT as I define it now has an exception-clause that follows that beat-condition. That clause specifies that two candidates can't beat eachother, and specifies which candidate beats the other when the beat-condition statement says that they both beat the other. By the way, I'm going to have to withdraw my claim that Symmetrical ICT as I now define it meets Later-No-Help. Because you can't make two unranked candidates beat eachother, I don't suppose LNHe is still complied with. But it's really as good as if it were. Though it doesn't strictly meet the letter of LNHe: When you don't rank two unacceptable candidates, you're still doing everything that you can to ensure that one of them will be beaten.If you rank one of them, you're only doing all that you can to ensure that a particular _one_ of them is beaten--the one that you didn't rank. But you're doing more to ensure that, if one of them is beaten, it will be the unranked one. ...and maybe the unranked one is the one who has more 1st rankings than do the acceptable candidates. That's why I withdraw the claim that Symmetrical ICT meets LNHe. But that involves information that you can't really know, and so strategic ranking of unacceptables won't be called-for. And, for one thing this isn't associated with a psychologically entrenched strategy-tendency like lesser-evil giveaway. For another thing, we're only talking about bottom-end strategy, which is much less important. But, in that regard, Symmetrical ICT guarantees something that unimproved Condorcet doesn't guarantee: By not ranking some two candidates, you're doing everything you can to ensure that one of those two will be beaten. In spite of LNHe-failure, there's really no need to rank unacceptable candidates in a u/e election. In contrast, unimproved Condorcet's u/a strategy calls for ranking the unacceptable candidates in reverse order of winnability, because otherwise you're not contributing to any of them being beaten by other unacceprables. Because that isn't needed in Symmetrical ICT, Symmetrical ICT has effectively as simple a u/a strategy as do Approval and Score. More so, really, because chicken dilemma is automatically avoided. But the important difference between improved and unimproved Condorcet is Improved Condorcet's FBC compliance and unimproved Condorcet's FBC failure. That's the most important property-gain with Improved Condorcet, in comparison to unimproved Condorcet. But ICT and Symmetrical ICT also automatically avoid the chicken dilemma nuisance. Because the chicken dilemma can keep you from supporting your 2nd choice, it's a nuisance that is more important than LNHe. As I've said, the chicken dilemma nuisance, though not an actual problem, is the nearest thing to a problem that Approval and Score have. Any rank method that doesn't get rid of the chicken dilemma doesn't improve significantly on Approval and Score. Therefore, there's no reason to bother wih any rank method that doesn't get rid of the chicken dilemma...and meet FBC. Summarizing the differences between Symmetrical ICT and unimproved Condorcet?: FBC, chicken dilemma, and the matter of whether or not you need to rank the unacceptable candidates in reverse order of winnabililty, as opposed to just not ranking any of them. (I"d like to clarify that, from now on, when I say "Symmetrical ICT", I'm referring to Symmetrical ICT as I define it now. I've recently asked the advocates of unimproved Condorcet (such as Beatpath, Ranked-Pairs, River, Goldfish, Kemeny, VoteFair, etc.) what advantages or desirable properties unimproved Condorcet has, that outweigh its disadvantages in comparison to ICT and Symmetrical ICT. I've also asked advocates of unimproved Condorcet what advantages or desirable properties it has that outweigh its disadvantages in comparison with Approval and Score. Of course the Condorcet Criterion is an answer to the latter question. But Condorcet Criterion compliance only means something if the worst strategy-needs are avoided, as they are in ICT and Symmetrical ICT. I suggest that unimproved Condorcet can't claim the Condorcet Criterion as an advantage, because unimproved Condorcet often won't have the benefit of the Condorcet Criterion, because many people will need to do other than rank sincerely. Approval's and Score's advantages in comparison to unimproved Condorcet are: FBC LNHe And, because of those, Approval and Score have the simplest and easiest u/a strategy: In Approval, rank the acceptable candidates, and none of the unacceptable candidates. In Score, top-rate the acceptables and bottom-rate the unacceptables. Mike Ossipoff ---- Election-Methods mailing list - see http://electorama.com/em for list info
