EM list-- I'd like to make a few brief comments regarding the Tideman vs Schulze discussion. First I'd like to discuss Tideman vs IBCM & DCD, in terms of a standard suggested by Blake. Blake suggested that if A beats B pairwise, then A should be more likely to finish ahead of B in the output ranking than vice-versa. (I'd just say that A should be more likely to win). Another way of saying that is that if we're comparing 2 methods, then a method is more appealing if its winner usually beats the other method's winner. The winner by the method known as IBCM or DCD usually beats Tideman's winner when the 2 methods pick different winners. DCD, like Tideman, is a Cycle Condorcet method, which (when defeats are measured by how many support the defeat) meets BC and all the defensive strategy criteria. *** Blake & Markus were also discussing which method, Tideman or Schulze does the best job of not rewarding truncation. I agree with the person who said that it isn't desirable to punish truncation, because truncation is a reasonable & natural way to vote, and shouldn't be considered as being done as offensive strategy. But it shouldn't be rewarded. I don't have an opinion on whether Tideman or Schulze does better in that regard. Because they're both Cycle Condorcet methods, they both meet GSFC, and both avoid letting supporters of a nonmember of the sincere Smith set from stealing the election for their candidate by truncation when a majority rank a sincere Smith set member over their candidate. (if we measure defeats by votes-against--I'll abbreviate that "wv", for "winning votes", because that term is used here). But if defeats are measured by margin-of-defeat, then I suggest that it's a meaningless question whether Tideman or Schulze does better at not rewarding truncation. That's because Schulze(margins) & Tideman(margins) both reward truncation in the biggest way, letting it steal the election from a CW who is ranked over the truncators' candidate by a majority, when no one votes unfelt preferences. No Condorcet version will do that. (Recent discussion has shown that it's reasonable to limit "Condorcet" to wv methods). In other words, Schulze(wv), Tideman(wv), SSD(wv), SD(wv) and DCD(wv) wouldn't ever reward truncation in the blatant way that every Margins method will, including Schulze(margins) & Tideman(margins). Mike Ossipoff ______________________________________________________ Get Your Private, Free Email at http://www.hotmail.com
