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<p>Kevin,<br>
<br>
<blockquote type="cite">
<pre class="moz-quote-pre" wrap="">I would not like to see SFC as totally obsolete, since it was one of the motivating
criteria (along with MD and weak FBC) for my methods MDDA and MAMPO :)</pre>
</blockquote>
<br>
Inventing those methods was some achievement as a thought
experiment to demonstrate that certain criteria are mutually
compatible. <br>
<br>
But MDDA spectacularly fails the maximum-absurdity criterion
Mono-add-Plump, a very interesting fact that isn't mentioned on
its electowiki page.<br>
<br>
<a class="moz-txt-link-freetext" href="https://electowiki.org/wiki/Majority_Defeat_Disqualification_Approval">https://electowiki.org/wiki/Majority_Defeat_Disqualification_Approval</a><br>
<blockquote type="cite">
<h2
style="color: rgb(0, 0, 0); margin: 1em 0px 0.25em; padding: 0px; overflow: hidden; border-bottom: 1px solid rgb(162, 169, 177); font-size: 1.5em; font-weight: normal; font-family: "Linux Libertine", Georgia, Times, serif; line-height: 1.375; font-style: normal; font-variant-ligatures: normal; font-variant-caps: normal; letter-spacing: normal; orphans: 2; text-align: start; text-indent: 0px; text-transform: none; widows: 2; word-spacing: 0px; -webkit-text-stroke-width: 0px; white-space: normal; background-color: rgb(255, 255, 255); text-decoration-thickness: initial; text-decoration-style: initial; text-decoration-color: initial;"><span
class="mw-headline" id="Procedure">Procedure</span></h2>
<p
style="margin: 0.5em 0px; color: rgb(32, 33, 34); font-family: sans-serif; font-size: 14px; font-style: normal; font-variant-ligatures: normal; font-variant-caps: normal; font-weight: 400; letter-spacing: normal; orphans: 2; text-align: start; text-indent: 0px; text-transform: none; widows: 2; word-spacing: 0px; -webkit-text-stroke-width: 0px; white-space: normal; background-color: rgb(255, 255, 255); text-decoration-thickness: initial; text-decoration-style: initial; text-decoration-color: initial;">The
voter submits a ranking of the candidates. The candidates
explicitly ranked are considered<span> </span><i>approved</i><span> </span>by
that voter.</p>
<p
style="margin: 0.5em 0px; color: rgb(32, 33, 34); font-family: sans-serif; font-size: 14px; font-style: normal; font-variant-ligatures: normal; font-variant-caps: normal; font-weight: 400; letter-spacing: normal; orphans: 2; text-align: start; text-indent: 0px; text-transform: none; widows: 2; word-spacing: 0px; -webkit-text-stroke-width: 0px; white-space: normal; background-color: rgb(255, 255, 255); text-decoration-thickness: initial; text-decoration-style: initial; text-decoration-color: initial;">A
candidate is<span> </span><i>dominated</i><span> </span>if
more than half of the voters rank some other candidate
strictly above him.</p>
<p
style="margin: 0.5em 0px; color: rgb(32, 33, 34); font-family: sans-serif; font-size: 14px; font-style: normal; font-variant-ligatures: normal; font-variant-caps: normal; font-weight: 400; letter-spacing: normal; orphans: 2; text-align: start; text-indent: 0px; text-transform: none; widows: 2; word-spacing: 0px; -webkit-text-stroke-width: 0px; white-space: normal; background-color: rgb(255, 255, 255); text-decoration-thickness: initial; text-decoration-style: initial; text-decoration-color: initial;">All
dominated candidates are eliminated, unless this would
eliminate all the candidates.</p>
<p
style="margin: 0.5em 0px; color: rgb(32, 33, 34); font-family: sans-serif; font-size: 14px; font-style: normal; font-variant-ligatures: normal; font-variant-caps: normal; font-weight: 400; letter-spacing: normal; orphans: 2; text-align: start; text-indent: 0px; text-transform: none; widows: 2; word-spacing: 0px; -webkit-text-stroke-width: 0px; white-space: normal; background-color: rgb(255, 255, 255); text-decoration-thickness: initial; text-decoration-style: initial; text-decoration-color: initial;">Of
remaining candidates, the one approved by the most voters is
elected.</p>
<h2
style="color: rgb(0, 0, 0); margin: 1em 0px 0.25em; padding: 0px; overflow: hidden; border-bottom: 1px solid rgb(162, 169, 177); font-size: 1.5em; font-weight: normal; font-family: "Linux Libertine", Georgia, Times, serif; line-height: 1.375; font-style: normal; font-variant-ligatures: normal; font-variant-caps: normal; letter-spacing: normal; orphans: 2; text-align: start; text-indent: 0px; text-transform: none; widows: 2; word-spacing: 0px; -webkit-text-stroke-width: 0px; white-space: normal; background-color: rgb(255, 255, 255); text-decoration-thickness: initial; text-decoration-style: initial; text-decoration-color: initial;"><span
class="mw-headline" id="Criteria">Criteria</span></h2>
<p
style="margin: 0.5em 0px; color: rgb(32, 33, 34); font-family: sans-serif; font-size: 14px; font-style: normal; font-variant-ligatures: normal; font-variant-caps: normal; font-weight: 400; letter-spacing: normal; orphans: 2; text-align: start; text-indent: 0px; text-transform: none; widows: 2; word-spacing: 0px; -webkit-text-stroke-width: 0px; white-space: normal; background-color: rgb(255, 255, 255); text-decoration-thickness: initial; text-decoration-style: initial; text-decoration-color: initial;"><b>MDDA</b><span> </span>satisfies
the<span> </span><a
href="https://electowiki.org/wiki/Favorite_Betrayal_criterion"
class="mw-redirect" title="Favorite Betrayal criterion"
style="text-decoration: none; color: rgb(51, 102, 204); background: none; overflow-wrap: break-word;">Favorite
Betrayal criterion</a>,<span> </span><a
href="https://electowiki.org/wiki/Strategy-Free_criterion"
class="mw-redirect" title="Strategy-Free criterion"
style="text-decoration: none; color: rgb(51, 102, 204); background: none; overflow-wrap: break-word;">Strategy-Free
criterion</a>, the<span> </span><a
href="https://electowiki.org/wiki/Strong_Defensive_Strategy_criterion"
title="Strong Defensive Strategy criterion"
style="text-decoration: none; color: rgb(51, 102, 204); background: none; overflow-wrap: break-word;">Strong
Defensive Strategy criterion</a><span> </span>(and<span> </span><a
href="https://electowiki.org/wiki/Minimal_Defense_criterion"
title="Minimal Defense criterion"
style="text-decoration: none; color: rgb(51, 102, 204); background: none; overflow-wrap: break-word;">Minimal
Defense criterion</a>), and<span> </span><a
href="https://electowiki.org/wiki/Monotonicity_criterion"
class="mw-redirect" title="Monotonicity criterion"
style="text-decoration: none; color: rgb(51, 102, 204); background: none; overflow-wrap: break-word;">monotonicity</a>.</p>
<p
style="margin: 0.5em 0px; color: rgb(32, 33, 34); font-family: sans-serif; font-size: 14px; font-style: normal; font-variant-ligatures: normal; font-variant-caps: normal; font-weight: 400; letter-spacing: normal; orphans: 2; text-align: start; text-indent: 0px; text-transform: none; widows: 2; word-spacing: 0px; -webkit-text-stroke-width: 0px; white-space: normal; background-color: rgb(255, 255, 255); text-decoration-thickness: initial; text-decoration-style: initial; text-decoration-color: initial;">It
fails<span> </span><a
href="https://electowiki.org/wiki/Strategic_nomination"
title="Strategic nomination"
style="text-decoration: none; color: rgb(51, 102, 204); background: none; overflow-wrap: break-word;">Clone-Winner</a>,
the<span> </span><a
href="https://electowiki.org/wiki/Plurality_criterion"
title="Plurality criterion"
style="text-decoration: none; color: rgb(51, 102, 204); background: none; overflow-wrap: break-word;">Plurality
criterion</a>, the<span> </span><a
href="https://electowiki.org/wiki/Generalized_Strategy-Free_criterion"
title="Generalized Strategy-Free criterion"
style="text-decoration: none; color: rgb(51, 102, 204); background: none; overflow-wrap: break-word;">Generalized
Strategy-Free criterion</a>, the<span> </span><a
href="https://electowiki.org/wiki/Condorcet_criterion"
class="mw-redirect" title="Condorcet criterion"
style="text-decoration: none; color: rgb(51, 102, 204); background: none; overflow-wrap: break-word;">Condorcet
criterion</a>, the<span> </span><a
href="https://electowiki.org/wiki/Smith_set"
title="Smith set"
style="text-decoration: none; color: rgb(51, 102, 204); background: none; overflow-wrap: break-word;">Smith
criterion</a>,<span> </span><a
href="https://electowiki.org/wiki/Participation_criterion"
title="Participation criterion"
style="text-decoration: none; color: rgb(51, 102, 204); background: none; overflow-wrap: break-word;">Participation</a>,
the<span> </span><a
href="https://electowiki.org/wiki/Majority_criterion"
title="Majority criterion"
style="text-decoration: none; color: rgb(51, 102, 204); background: none; overflow-wrap: break-word;">Majority
criterion for solid coalitions</a>, and<span> </span><a
href="https://electowiki.org/wiki/Later-no-harm_criterion"
title="Later-no-harm criterion"
style="text-decoration: none; color: rgb(51, 102, 204); background: none; overflow-wrap: break-word;">Later-no-harm</a>.</p>
<br class="Apple-interchange-newline">
</blockquote>
<br>
</p>
<pre
style="white-space: pre-wrap; color: rgb(0, 0, 0); font-style: normal; font-variant-ligatures: normal; font-variant-caps: normal; font-weight: 400; letter-spacing: normal; orphans: 2; text-align: start; text-indent: 0px; text-transform: none; widows: 2; word-spacing: 0px; -webkit-text-stroke-width: 0px; text-decoration-thickness: initial; text-decoration-style: initial; text-decoration-color: initial;">25: A>B
26: B>C
23: C>A
04: C
78 ballots (majority threshold = 40)
B>C 51-27, C>A 53-25, A>B 48-26. Implicit Approval scores: C 53, B 51, A 48.
All the candidates have a majority-strength defeat, so none are eliminated and the most approved candidate, C, wins.
Say we now add 22 ballots that all plump (i.e. bullet vote) for C:
25: A>B
26: B>C
23: C>A
26: C
100 ballots (majority threshold = 51)
B>C 51-49, C>A 75-25, A>B 48-26. Implicit Approval scores: C 75, B 51, A 48.
Now only B is without a "majority-strength defeat", so the winner changes from C to B.
Of course the method also fails Irrelevant Ballots Independence. If we now add 3 ballots that plump for X, the majority threshold rises to 52 and so C's majority-strength defeat goes away and C wins again by being the most approved candidate.
This demonstration of Mono-add-Plump failure doesn't apply to MAMPO, but that method would also fail Irrelevant Ballots Independence. It may be far less bad.
<a class="moz-txt-link-freetext" href="https://electowiki.org/wiki/Majority_Approval,_Minimum_Pairwise_Opposition">https://electowiki.org/wiki/Majority_Approval,_Minimum_Pairwise_Opposition</a>
<blockquote type="cite"><h2
style="color: rgb(0, 0, 0); margin: 1em 0px 0.25em; padding: 0px; overflow: hidden; border-bottom: 1px solid rgb(162, 169, 177); font-size: 1.5em; font-weight: normal; font-family: "Linux Libertine", Georgia, Times, serif; line-height: 1.375; font-style: normal; font-variant-ligatures: normal; font-variant-caps: normal; letter-spacing: normal; orphans: 2; text-align: start; text-indent: 0px; text-transform: none; widows: 2; word-spacing: 0px; -webkit-text-stroke-width: 0px; white-space: normal; background-color: rgb(255, 255, 255); text-decoration-thickness: initial; text-decoration-style: initial; text-decoration-color: initial;"><span
class="mw-headline" id="Procedure">Procedure</span></h2><p
style="margin: 0.5em 0px; color: rgb(32, 33, 34); font-family: sans-serif; font-size: 14px; font-style: normal; font-variant-ligatures: normal; font-variant-caps: normal; font-weight: 400; letter-spacing: normal; orphans: 2; text-align: start; text-indent: 0px; text-transform: none; widows: 2; word-spacing: 0px; -webkit-text-stroke-width: 0px; white-space: normal; background-color: rgb(255, 255, 255); text-decoration-thickness: initial; text-decoration-style: initial; text-decoration-color: initial;">The voter submits a ranking of the candidates. The candidates explicitly ranked are considered<span> </span><i>approved</i><span> </span>by that voter.</p><p
style="margin: 0.5em 0px; color: rgb(32, 33, 34); font-family: sans-serif; font-size: 14px; font-style: normal; font-variant-ligatures: normal; font-variant-caps: normal; font-weight: 400; letter-spacing: normal; orphans: 2; text-align: start; text-indent: 0px; text-transform: none; widows: 2; word-spacing: 0px; -webkit-text-stroke-width: 0px; white-space: normal; background-color: rgb(255, 255, 255); text-decoration-thickness: initial; text-decoration-style: initial; text-decoration-color: initial;">The<span> </span><i>score</i><span> </span>for candidate<span> </span><i>X</i><span> </span>against candidate<span> </span><i>Y</i><span> </span>is equal to the number of voters ranking<span> </span><i>X</i><span> </span>above<span> </span><i>Y</i>. The<span> </span><i>max score</i><span> </span>of candidate<span> </span><i>X</i><span> </span>is the largest score of any other candidate against<span> </span><i>X</i>.</p><p
style="margin: 0.5em 0px; color: rgb(32, 33, 34); font-family: sans-serif; font-size: 14px; font-style: normal; font-variant-ligatures: normal; font-variant-caps: normal; font-weight: 400; letter-spacing: normal; orphans: 2; text-align: start; text-indent: 0px; text-transform: none; widows: 2; word-spacing: 0px; -webkit-text-stroke-width: 0px; white-space: normal; background-color: rgb(255, 255, 255); text-decoration-thickness: initial; text-decoration-style: initial; text-decoration-color: initial;">If nobody is approved by more than half of the voters, then the candidate approved by the most voters is elected.</p><p
style="margin: 0.5em 0px; color: rgb(32, 33, 34); font-family: sans-serif; font-size: 14px; font-style: normal; font-variant-ligatures: normal; font-variant-caps: normal; font-weight: 400; letter-spacing: normal; orphans: 2; text-align: start; text-indent: 0px; text-transform: none; widows: 2; word-spacing: 0px; -webkit-text-stroke-width: 0px; white-space: normal; background-color: rgb(255, 255, 255); text-decoration-thickness: initial; text-decoration-style: initial; text-decoration-color: initial;">Otherwise, the candidate with the lowest max score, who is approved by more than half of the voters, is elected.</p></blockquote>
Chris B.
</pre>
<br class="Apple-interchange-newline">
<br>
<div class="moz-cite-prefix">On 2/06/2024 7:23 am, Kevin Venzke
wrote:<br>
</div>
<blockquote type="cite"
cite="mid:344899313.1038074.1717278810434@mail.yahoo.com">
<pre class="moz-quote-pre" wrap="">Hi all,
When I test for SFC compliance the rule on cast votes is that if there is no
majority over A, and A has a majority over B, then B can't win.
This is kind of a flip side of MD / SDSC because, if you were forced to explain MD
in terms of a graph of majority-strength defeats, it would say that if A has a
majority over B and B doesn't have a majority over anyone, then B can't win.
MD basically says that if there are two frontrunners and everyone truncates their
less liked frontrunner, then the worse frontrunner won't win. If this property
doesn't hold, it means the majority has done something to stop the method from
"seeing" their majority, which is surely that they ranked other candidates above
the preferred frontrunner. So MD is mostly about compromise incentive.
SFC is probably going to be about truncation. When a method fails it, most likely
it's because the majority gave the election away to a less liked compromise choice.
For example:
20 C>A>B
35 A>B
5 B
40 D
Here B is the implicit approval winner, but by SFC B should not win, because it
means it was not safe for the A voters to rank B.
I would not like to see SFC as totally obsolete, since it was one of the motivating
criteria (along with MD and weak FBC) for my methods MDDA and MAMPO :)
Kevin
votingmethods.net
</pre>
</blockquote>
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