One reason why voting-system discussion doesn't get anywhere is because people are only trying to justify their pre-existing positions. Speaking for myself, I don't want to be like that. That isn't genuine discussion.
Sure, the clone-independent properties of such methods as Beatpath have some value, and, for fairness, one should look at what would have to be traded in order to get such properties as Clone-Independence, MMC, etc. Then, it would desirable to compare, without prejudice, the desirability of what would be lost in the trade to what would be gained in the trade. Most likely, Improved Condorcet could be used with any Condorcet completion (any solution for when there isn't exactly one unbeaten candidate). Kevin proposed Approval, which gives the method ICA.. Chris proposed top-count, because it meets CD, which gives the method that I call ICT. But Improved Condorcet could be used (at top end, or at both top and bottom ends) with any other Condorcet completion too. For instance _maybe_, if IC were completed with Beatpath, SSD or Ranked-Pairs, FBC could be kept, and CD would merely be traded for Clone-Independence and maybe MMC, Smith, Condorcet-Loser, etc. I don't know how many of the desirable properties of Symmetrical ICT and Beatpath or Ranked-Pairs could thereby be retained. At one time when I looked at Smith, it seemed to me that it was incompatible with FBC. If that's correct, then, since Ranked-Pairs and Beatpath meet Smith, then it couldn't just be a matter of trading CD for Ranked-Pairs or Beatpath advantages--FBC would be lost in the trade as well, and that would be entirely unacceptable. But since, right now, I'm not sure about that incompatibility, it could be worth considering whether it would be worthwhile, for example, to trade CD for Clone-Independence. Would it be a good trade? Kristofer's arguments should be considered. He doesn't like the Approval strategy that a non-clone-independent method can have in a clone situation. He called it "manual DSV" and recommended actual DSV instead. For one thing, as I said, DSV has strategy too. It seems to me that its strategy was like that of TUC(wv). Aside from that, where to start, regarding the desirability of the trade? What Kristofer is saying is that, when ICT doesn't improve on Approval, it has Approval strategy. If so, then ICT can be called an improvement on Approval. One reason why voting-system discussion doesn't get anywhere is because people are only trying to justify their pre-existing positions. Speaking for myself, I don't want to be like that. That isn't genuine discussion. Sure, the clone-independent properties of such methods as Beatpath have some value, and, for fairness, one should look at what would have to be traded in order to get such properties as Clone-Independence, MMC, etc. Then, it would desirable to compare, without prejudice, the desirability of what would be lost in the trade to what would be gained in the trade. Most likely, Improved Condorcet could be used with any Condorcet completion (any solution for when there isn't exactly one unbeaten candidate). Kevin proposed Approval, which gives the method ICA.. Chris proposed top-count, because it meets CD, which gives the method that I call ICT. But Improved Condorcet could be used (at top end, or at both top and bottom ends) with any other Condorcet completion too. For instance _maybe_, if IC were completed with Beatpath, SSD or Ranked-Pairs, FBC could be kept, and CD would merely be traded for Clone-Independence and maybe MMC, Smith, Condorcet-Loser, etc. I don't know how many of the desirable properties of Symmetrical ICT and Beatpath or Ranked-Pairs could thereby be retained. At one time when I looked at Smith, it seemed to me that it was incompatible with FBC. If that's correct, then, since Ranked-Pairs and Beatpath meet Smith, then it couldn't just be a matter of trading CD for Ranked-Pairs or Beatpath advantages--FBC would be lost in the trade as well, and that would be entirely unacceptable. But since, right now, I'm not sure about that incompatibility, it could be worth considering whether it would be worthwhile, for example, to trade CD for Clone-Independence. Would it be a good trade? Kristofer's arguments should be considered. He doesn't like the Approval strategy that a non-clone-independent method can have in a clone situation. He called it "manual DSV" and recommended actual DSV instead. For one thing, as I said, DSV has strategy too. It seems to me that its strategy was like that of TUC(wv). Aside from that, where to start, regarding the desirability of the trade? What Kristofer is saying is that, when ICT doesn't improve on Approval, it has Approval strategy. If so, then ICT can be called an improvement on Approval. Improving on Approval is easier said than done. Kristofer would like to get rid of Approval's strategy need. The problem is that, when we do that, we tend to get worse strategy needs. If CD can be gained, without making anything worse than Approval, then we have a net gain. It could be argued that, in my chicken dilemma examples, the old Approval bad-example, if A and C are cloned, and the A voters and C voters split their vote among the clones, then, ICT won't benefit from its CD compliance, and the B voters can successfully defect. Yes, but they'd still have to know that B has the most top-votes (regardless of whether that's because of clones and split vote among the A voters and the C voters). Likewise, for successful burial strategy, the B voters would need to know that too. So I suggest that ICT retains uniquely powerful deterrence against defection and burial. If we compare ICT to ordinary Beatpath, the difference is between, at worst, Approval strategy, and the more drastic strategy-need of Beatpath. But I was discussing the trade of CD for Clone-Independence. But I suggest that the chicken dilemma is worse than ordinary Approval strategy. That suggests that the trade is unfavorable. So far, I haven't been limiting the discussion to u/a elections. When we specifically discuss u/a elections, the conclusions become more obvious and clear-cut: I suggest that our official public elections, at least for state and national office, are always u/a elections. Let me repeat the u/a strategy of the methods we're discussing: Approval: Approve all of the acceptables, and none of the unacceptables. Score: Top-rate all of the acceptables. Bottom-rate all of the unacceptables. ICT: Top-rank the acceptables. Rank the unacceptables below top, in reverse order of winnability. Beatpath: Beatpath bottom-end: Rank the unacceptables below the acceptables, in reverse order of winnability. Beatpath top-end: Unknown. I guess try to top-rank the acceptables most likely to win, and rank the other unacceptables below top. Symmetrical ICT: Top-rank the acceptables. Bottom-rank the unacceptables. (That's like Approval strategy. Approval strategy is the best that you can get, except for gaining CD compliance) Symmetrical IC-Beatpath: Maybe the same as Symmetrical ICT, if FBC isn't lost. But CD is lost, and the chicken dilemma is retained. That looks like a net loss, in comparison to SICT. Since the best you can get is Approval strategy anyway, the Approval strategy that non-clone-independent methods can have in clone situations isn't a loss. Mike Ossipoff ---- Election-Methods mailing list - see http://electorama.com/em for list info