Warren, --- Warren Smith <[EMAIL PROTECTED]> a écrit : > MDDA *if* all votes are full rank orderings, is just the "Smith set" > and often yields a tied election. In fact often the Smith set is the entire > set of candidates. (In most of Australia full rank orderings - i.e. none > omitted - > are demanded by law.)
If everyone approves all the candidates, then yes, there will likely be a tie. But there is no connection with the Smith set. > This seems a severe problem with MDDA and probably is a good reason to prefer > "Deluxe MDDA" which will (in the limit of a large number of voters and with > some randomness) > generically not be tied, even with all voters expressing maximum information. > I'm not a fan of an explicit approval cutoff for MDDA, since it makes burial strategy risk-free unless your opponents also use burial strategy. > Properties of Deluxe MDDA: > It is fairly simply defined, though not as simple as range voting. > > Deluxe MDDA seems plainly monotonic in both senses (ranking and approval > thresh) simultaneously. > > It elects a Condorcet Winner if one exists. > > It refuses to elect a Condorcet loser. (Deluxe) MDDA doesn't satisfy Condorcet or Condorcet Loser. It only considers wins with more than half of the voters on the winning side. > It is generically untied. > > It is Clone-immune. (Deluxe) MDDA doesn't satisfy Clone Independence. If candidate A wins, it is possible that when A is replaced by a set of candidates in a cycle, the winner won't be in this set. >MDDA fails "add top". That is, if you add some identical honest votes ranking >A top, >that can harm A (e.g. by creating a Condorcet winner [who is not A] >who then wins, whereas previously there was a Condorcet cycle and A was the >winner >on approval counts). MMDA fails Mono-add-top because adding A-top votes could cause a lower-ranked candidate to lose a majority-strength loss, so that this candidate is the only one not disqualified. >Now this [mono-add-top failure] may not technically count as an FBC failure, >because >I daresay there >exists some way to rank A top and dishonestly order the remaining candidates, >which still leaves A the winner. True. Just rank the candidate (who would win with a sincere vote) last. > However, in practice, it may have a very similar >effect to FBC failure. I don't think so, because the problem is not caused by ranking A first. In this situation, lowering A is not helpful. Kevin Venzke ___________________________________________________________________________ Appel audio GRATUIT partout dans le monde avec le nouveau Yahoo! Messenger Téléchargez cette version sur http://fr.messenger.yahoo.com ---- Election-methods mailing list - see http://electorama.com/em for list info