<div dir="ltr">There is a theory that later-no-harm is not desirable, and satisfying participation proper may not be desirable either by similar logic.<div><br></div><div>I'm not certain about Mono-Add-Top. Alternative smith fails monotonicity; although by adding a ballot that ranks X strictly above all candidates, X (winner) would necessarily have a larger plurality first-vote than Y. If Y is in the Smith set already, it has fewer plurality first-votes than X, and retains this going down the rounds, so ranking X first should keep it ahead of Y in the elimination order.</div><div><br></div><div>You can add a ballot that ranks only X and removes candidate Z from the Smith set, strengthening Y and causing Y to defeat X. To me, this seems unlikely; or, rather, it seems unlikely to matter in practice. You'll find that X has to be strong enough with voters to be in the running anyway, so your best bet is to vote—and if you keep casting ballots that rank X above everyone else, X is eventually going to become the majority winner. These are anomalies along the way.</div></div><br><div class="gmail_quote"><div dir="ltr">On Thu, Aug 9, 2018 at 1:51 PM Kevin Venzke <<a href="mailto:stepjak@yahoo.fr">stepjak@yahoo.fr</a>> wrote:<br></div><blockquote class="gmail_quote" style="margin:0 0 0 .8ex;border-left:1px #ccc solid;padding-left:1ex"><div><div style="font-family:Helvetica Neue,Helvetica,Arial,sans-serif;font-size:16px"><div style="font-family:Helvetica Neue,Helvetica,Arial,sans-serif;font-size:16px"><div></div>
<div>Note that Condorcet methods aren't necessarily Smith-efficient. (For example, plain minmax methods, or</div><div>"Condorcet//Approval".) At least one Condorcet method satisfies mono-add-top, but Smith methods, in my</div><div>opinion, probably can't.</div><div><br></div><div>I don't think it's worth worrying about Participation too much. Satisfying Participation seems to greatly</div><div>constrain what kinds of logic a method can use. And the people who advocate methods that satisfy Participation</div><div>probably aren't so dedicated to that aspect in particular.</div><div><br></div><div>Kevin</div><div><br></div><div><br></div>
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Le jeudi 9 août 2018 à 12:13:12 UTC−5, John <<a href="mailto:john.r.moser@gmail.com" target="_blank">john.r.moser@gmail.com</a>> a écrit :
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<div><div id="m_8516043519999097208ydp2304d169yiv1280737514"><div dir="ltr"><br><br><div class="m_8516043519999097208ydp2304d169yiv1280737514gmail_quote"><div dir="ltr">On Thu, Aug 9, 2018 at 12:43 PM Arthur Wist <<a href="mailto:arthur.wist@gmail.com" rel="nofollow" target="_blank">arthur.wist@gmail.com</a>> wrote:<br></div><blockquote class="m_8516043519999097208ydp2304d169yiv1280737514gmail_quote" style="margin:0px 0px 0px 0.8ex;border-left:1px solid rgb(204,204,204);padding-left:1ex">Hi,<br>
<br>
I suspect you didn't receive the below email since Markus Schulze<br>
elected to not copy you onto his response. I've decided to thus foward<br>
it to you.<br>
<br>
Kind regards,<br>
<br>
<br>
Arthur Wist<br>
<br>
<br>
---------- Forwarded message ----------<br>
From: Markus Schulze <<a href="mailto:markus.schulze8@gmail.com" rel="nofollow" target="_blank">markus.schulze8@gmail.com</a>><br>
Date: 7 August 2018 at 18:41<br>
Subject: Re: [EM] Schulze Method shortcut<br>
To: <a href="mailto:election-methods@electorama.com" rel="nofollow" target="_blank">election-methods@electorama.com</a><br>
<br>
<br>
Hallo,<br>
<br>
> The Schulze method elects from the Schwartz set using a beatpath<br>
> algorithm. The usual explanation is incredibly complex, and complexity is<br>
> undesirable but often necessary. Would this method be equivalent?<br>
><br>
> 1. Eliminate all candidates not in the Schwartz set.<br>
> 2. If there is one candidate left, elect that candidate.<br>
> 3. Exclude the pairwise race with the smallest win margin.<br>
> 4. Repeat.<br>
><br>
> Tideman's Alternative Schwartz is this, except #3 eliminates the candidate<br>
> with the fewest first-rank votes. I am leaning toward Tideman's<br>
> Alternative Schwartz or Smith for their simplicity and resistance to<br>
> tactical voting and nomination.<br>
<br>
(1) The best possible election method according to the underlying heuristic<br>
of instant-runoff voting will always be instant-runoff voting. Therefore,<br>
I don't think that any supporter of instant-runoff voting will be convinced<br>
by a hybrid of Condorcet voting and instant-runoff voting.<br>
<br>
(2) The Schulze method satisfies monotonicity and reversal symmetry.<br>
Instant-runoff voting and Tideman's alternative methods violate<br>
monotonicity and reversal symmetry. Therefore, monotonicity and<br>
reversal symmetry cannot be used anymore as arguments against<br>
instant-runoff voting.<br>
<br></blockquote><div><br></div><div>IRV tends to squeeze out candidates with weak first-rank votes but strong second-rank votes.</div><div> </div><blockquote class="m_8516043519999097208ydp2304d169yiv1280737514gmail_quote" style="margin:0px 0px 0px 0.8ex;border-left:1px solid rgb(204,204,204);padding-left:1ex">
(3) Promoting a hybrid of Condorcet voting and instant-runoff voting<br>
will make the audience believe that there is a fundamental problem<br>
when there is no Condorcet winner and that every possible way to solve<br>
a situation without a Condorcet winner necessarily contains arbitrary<br>
decisions. However, election methods like the Schulze method solve<br>
situations without a Condorcet winner in a consistent manner without<br>
having to step outside their underlying heuristic, without having to<br>
resort to some other method, and without having to sacrifice<br>
compliance with important criteria.<br>
<br></blockquote><div><br></div><div>Condorcet methods are Smith-efficient: they identify a particularly-suitable set of candidates meeting a sort of mutual majority criteria (strong support overall) and elect from that. When that set is exactly one candidate, it is the Condorcet candidate.</div><div><br></div><div>Because these attempt to identify a strong candidate instead of a "winner" (someone with a certain number of votes—the most, a majority, or a quota), they can have some difficulty finding a resolution. That is to say: the strongest candidate defeats all others; yet that candidate may not exist, and so you find a set of such strong candidates.</div><div><br></div><div>Each underlying heuristic, thus, is designed to identify a particular strong candidate—a "winner"—in a way which elects from this set of strong candidates. They're influenced in different ways (best ranking overall versus most broad acceptance or whatnot; one method even attempts to change the fewest votes to elect the candidate "closest to being the Condorcet candidate").</div><div><br></div><div>This decision is, itself, an arbitrary one: you select one of these voting systems based on how you feel about picking one of multiple eligible suitors. Score voters would probably lean toward Schulze more than Ranked Pairs because Schulze does something more akin to finding the candidate with the best marginal utility instead of the strongest rankings.</div><div><br></div><div> Any ISDA method effectively throws out non-Smith candidates. Doing so explicitly is thus similar in theory to using any so-called Condorcet method. Tideman's Alternative Smith, for example, might find the plurality first-rank loser (which IRV eliminates) is a strong candidate in the Smith set, and second rank on many non-Smith-first-rank ballots, thus eliminating some other Smith candidate first. This can lead to that candidate winning.</div><div><br></div><div>Alternative Smith <i>is</i> an underlying heuristic; while any ISDA method like Schulze is effectively "eliminate all non-Schwartz candidates and apply this heuristic" because the heuristic eliminates all non-Schwartz candidates. The same is true of Ranked Pairs and other ISDA methods. Schulze and Ranked Pairs have much-more-complex heuristics than Alternative Smith.</div><div><br></div><blockquote class="m_8516043519999097208ydp2304d169yiv1280737514gmail_quote" style="margin:0px 0px 0px 0.8ex;border-left:1px solid rgb(204,204,204);padding-left:1ex">
(4) "I am leaning toward Tideman's Alternative Schwartz or Smith<br>
for their simplicity and resistance to tactical voting and nomination."<br>
I don't see why Tideman's alternative methods are supposed to be more<br>
resistant to tactical voting and nomination.<br></blockquote><div><br></div><div>It inherits that from IRV.</div><div><br></div><div><a href="http://www.votingmatters.org.uk/ISSUE29/I29P1.pdf" rel="nofollow" target="_blank">http://www.votingmatters.org.uk/ISSUE29/I29P1.pdf</a><br></div><div><br></div><div> </div><blockquote class="m_8516043519999097208ydp2304d169yiv1280737514gmail_quote" style="margin:0px 0px 0px 0.8ex;border-left:1px solid rgb(204,204,204);padding-left:1ex">
Markus Schulze<br>
<br>
----<br>
Election-Methods mailing list - see <a href="http://electorama.com/em" rel="nofollow" target="_blank">http://electorama.com/em</a> for list info<br>
</blockquote></div></div></div>----<br>Election-Methods mailing list - see <a href="http://electorama.com/em" rel="nofollow" target="_blank">http://electorama.com/em </a>for list info<br></div>
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