<html><body><div style="color:#000; background-color:#fff; font-family:times new roman, new york, times, serif;font-size:12pt"><div style="RIGHT: auto"><SPAN style="RIGHT: auto"><VAR id=yui-ie-cursor></VAR>They are quirky because of IIA. The papers on this are from the 1970's. Quote Wikipedia:</SPAN></div>
<div style="RIGHT: auto"><SPAN style="RIGHT: auto"></SPAN> </div>
<div style="RIGHT: auto"><SPAN style="RIGHT: auto">"The <B style="RIGHT: auto">Gibbard–Satterthwaite theorem</B>, named after <A title="Allan Gibbard" style="RIGHT: auto" href="http://fr.mg40.mail.yahoo.com/wiki/Allan_Gibbard"><FONT style="RIGHT: auto" color=#0645ad>Allan Gibbard</FONT></A> and <A title="Mark Satterthwaite" style="RIGHT: auto" href="http://fr.mg40.mail.yahoo.com/wiki/Mark_Satterthwaite"><FONT style="RIGHT: auto" color=#0645ad>Mark Satterthwaite</FONT></A>, is a </SPAN></div>
<div style="RIGHT: auto"><SPAN style="RIGHT: auto">result about the deterministic <A title="Voting system" href="http://fr.mg40.mail.yahoo.com/wiki/Voting_system"><FONT color=#0645ad>voting systems</FONT></A> that choose a single winner using only the preferences </SPAN></div>
<div style="RIGHT: auto"><SPAN style="RIGHT: auto">of the voters, where each voter ranks all candidates in order of preference. The Gibbard–Satterthwaite </SPAN></div>
<div style="RIGHT: auto"><SPAN style="RIGHT: auto">theorem states that, for three or more candidates, one of the following three things must hold for every </SPAN></div>
<div style="RIGHT: auto"><SPAN style="RIGHT: auto">voting rule:</div>
<OL>
<LI>The rule is dictatorial (i.e., there is a single individual who can choose the winner), or
<LI>There is some candidate who can never win, under the rule, or
<LI>The rule is susceptible to <A title="Tactical voting" href="http://fr.mg40.mail.yahoo.com/wiki/Tactical_voting"><FONT color=#0645ad>tactical voting</FONT></A>, in the sense that there are conditions under which a voter </LI></OL>
<div>with full knowledge of how the other voters are to vote and of the rule being used would have an incentive to vote in a manner that does not reflect his preferences. "</div>
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<div>I do wish we only posted in text. If I quote an html email as text I don't get any > symbols anymore to mark</div>
<div>what the other person said. And if I quote it as html, I have to supply my own indentation and still don't get </div>
<div>any marker next to the quoted text.</div>
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<div>Kevin</SPAN></div>
<div style="RIGHT: auto"><SPAN style="RIGHT: auto"></SPAN> </div>
<div style="RIGHT: auto"><SPAN style="RIGHT: auto"></SPAN> </div>
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<DIV class=hr style="BORDER-RIGHT: #ccc 1px solid; PADDING-RIGHT: 0px; BORDER-TOP: #ccc 1px solid; PADDING-LEFT: 0px; FONT-SIZE: 0px; PADDING-BOTTOM: 0px; MARGIN: 5px 0px; BORDER-LEFT: #ccc 1px solid; LINE-HEIGHT: 0; PADDING-TOP: 0px; BORDER-BOTTOM: #ccc 1px solid; HEIGHT: 0px" readonly="true" contenteditable="false"></DIV><B><SPAN style="FONT-WEIGHT: bold">De :</SPAN></B> David L Wetzell <wetzelld@gmail.com><BR><B><SPAN style="FONT-WEIGHT: bold">À :</SPAN></B> Jameson Quinn <jameson.quinn@gmail.com> <BR><B><SPAN style="FONT-WEIGHT: bold">Cc :</SPAN></B> election-methods@lists.electorama.com <BR><B><SPAN style="FONT-WEIGHT: bold">Envoyé le :</SPAN></B> Dimanche 19 février 2012 19h53<BR><B><SPAN style="FONT-WEIGHT: bold">Objet :</SPAN></B> [EM] élection de trois élection de trois<BR></FONT></DIV><BR>
<DIV id=yiv1159033145>It seems quite a few election rules get quirky in one way or the other with a 3-way competitive election.<BR><BR>That might be a point worth considering in the abstract in a paper or something.... why are 3-way single-winner elections quirky?
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<DIV>dlw<BR><BR>
<DIV class=yiv1159033145gmail_quote>On Sun, Feb 19, 2012 at 5:31 PM, Jameson Quinn <SPAN dir=ltr><<A href="mailto:jameson.quinn@gmail.com" target=_blank rel=nofollow ymailto="mailto:jameson.quinn@gmail.com">jameson.quinn@gmail.com</A>></SPAN> wrote:<BR>
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<DIV style="FONT-SIZE: 12pt">..., cuz the simple fact of the matter is that IRV works best with only 3 candidates. </DIV></DIV></DIV></DIV></BLOCKQUOTE>
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<DIV>2.5, actually.</DIV><SPAN class=yiv1159033145HOEnZb><FONT color=#888888>
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<DIV>Jameson </DIV></FONT></SPAN></DIV></BLOCKQUOTE></DIV><BR></DIV></DIV><BR>----<BR>Election-Methods mailing list - see <A href="http://electorama.com/em" target=_blank>http://electorama.com/em</A> for list info<BR><BR><BR></DIV></DIV></div></body></html>