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<div class="moz-cite-prefix">On 11/23/2016 10:59 AM, Kevin Venzke
wrote:<br>
<br>
<blockquote type="cite"><span style="font-size: 16px;"
id="yui_3_16_0_1_1479854184911_61103">Hmm, with a movable
cutoff MDDA already violates Plurality with three candidates.
Do you think symmetric-completion of the bottom can save it?</span></blockquote>
<br>
Yes.<br>
<br>
Something Toby Pereira wrote (9 Nov. 2016) regarding "Irrelevant
Ballots" got me thinking. The criterion I defined just talks about
ballots <br>
that plump for nobody, but there can also be a problem with
ballots that only vote nobodies below, say, equal-top.<br>
<br>
Under MDDA with symmetric completion only at the bottom, adding
ballots like that can wash away "majority-defeat"<br>
disqualifications and make the result less Condorcet-consistent.<br>
<br>
This has led me to think of a modification to fix this problem
that looks to be too good to be true, but so far I can't see how.<br>
<br>
*Voters submit rankings with an explicit approval cutoff. (I
prefer default placement to be just below candidates ranked below
no-one).<br>
<br>
On the ballots that have been symmetrically completed at the
bottom, find the smallest set S of candidate/s that
majority-strength pairwise<br>
beat all the outside-S candidates.<br>
<br>
Disqualify the outside-S candidate/s and delete all the ballots
that make no distinction among the inside-S candidates.<br>
<br>
Repeat as many times as possible. If at the end of this process
more than one candidate hasn't been disqualified, elect the<br>
one of those by normal MDDA (SC).*<br>
<br>
I am fearful that this might fail FBC and/or mono-raise, but I
can't (yet) see how it does.<br>
<br>
45: A>B>>C<br>
10: A=B<br>
40: B<br>
05: C<br>
<br>
100 ballots. After symmetrically completing at the bottom we get
A>B 47.5 - 42.5, A>C 75-25, B>C 95-5.<br>
<br>
Normal MDDA(SC) disqualifies only C and then elects the most
approved candidate, B.<br>
<br>
My suggested version first disqualifies C and then deletes the 5
C and 10 A=B ballots and then disqualifies B leaving A (the
CW)<br>
as the winner.<br>
<br>
What do you think?<br>
<br>
Chris Benham<br>
<br>
<br>
On 11/23/2016 10:59 AM, Kevin Venzke wrote:<br>
</div>
<blockquote cite="mid:1434287094.44562.1479860969145@mail.yahoo.com"
type="cite">
<div style="color:#000; background-color:#fff;
font-family:HelveticaNeue, Helvetica Neue, Helvetica, Arial,
Lucida Grande, sans-serif;font-size:12px">
<div id="yui_3_16_0_1_1479854184911_60274"><span><font size="3">Hi
Chris,</font></span></div>
<div class="qtdSeparateBR" id="yui_3_16_0_1_1479854184911_60273"><br>
<br>
</div>
<div class="yahoo_quoted" id="yui_3_16_0_1_1479854184911_60298"
style="display: block;">
<div id="yui_3_16_0_1_1479854184911_60297">
<div id="yui_3_16_0_1_1479854184911_60296">
<div dir="ltr" id="yui_3_16_0_1_1479854184911_60295"
style="font-family: HelveticaNeue, "Helvetica
Neue", Helvetica, Arial, "Lucida Grande",
sans-serif; font-size: 16px;"> <font
id="yui_3_16_0_1_1479854184911_60294" face="Arial"
size="2">
<hr id="yui_3_16_0_1_1479854184911_62295" size="1"> <b
id="yui_3_16_0_1_1479854184911_62869"><span
style="font-weight:bold;"
id="yui_3_16_0_1_1479854184911_62868">De :</span></b>
C.Benham <a class="moz-txt-link-rfc2396E" href="mailto:cbenham@adam.com.au"><cbenham@adam.com.au></a><br>
<b><span style="font-weight: bold;">À :</span></b>
Michael Ossipoff <a class="moz-txt-link-rfc2396E" href="mailto:email9648742@gmail.com"><email9648742@gmail.com></a> <br>
<b id="yui_3_16_0_1_1479854184911_62872"><span
style="font-weight: bold;"
id="yui_3_16_0_1_1479854184911_62871">Cc :</span></b>
EM <a class="moz-txt-link-rfc2396E" href="mailto:election-methods@lists.electorama.com"><election-methods@lists.electorama.com></a>;
Forest Simmons <a class="moz-txt-link-rfc2396E" href="mailto:fsimmons@pcc.edu"><fsimmons@pcc.edu></a><br>
<b><span style="font-weight: bold;">Envoyé le :</span></b>
Mardi 22 novembre 2016 10h51<br>
<b><span style="font-weight: bold;">Objet :</span></b>
Re: [EM] Trying to have CD, protect strong top-set,
and protect middle candidates too<br>
</font> </div>
<div class="y_msg_container"
id="yui_3_16_0_1_1479854184911_60302"><br>
<div id="yiv4410041191">
<div id="yui_3_16_0_1_1479854184911_60301">
<div class="yiv4410041191moz-cite-prefix"
id="yui_3_16_0_1_1479854184911_60300"><span
style="font-size: 16px;"
id="yui_3_16_0_1_1479854184911_60845">On
11/22/2016 9:25 AM, Michael Ossipoff wrote:</span><br
clear="none">
<br id="yui_3_16_0_1_1479854184911_60832"
clear="none">
<span style="font-size: 16px;"
id="yui_3_16_0_1_1479854184911_60843">>>With
</span><font id="yui_3_16_0_1_1479854184911_60876"
size="3">MDDTR, if your plump for X makes hir
lose, it's because you added a ballot. It has
nothing whatsoever to do with the fact that the
new ballot plumped for X.<br>
>>Your ballot made X lose in spite of the
fact that it was a plump for X, not because it
was a plump for X.<br>
>>But in IRV, when you make X lose by
raising hir from last place to 1st place, that
raising of X was the only thing that you did,
and it is the reason why X lost.</font></div>
<div class="yiv4410041191moz-cite-prefix"
id="yui_3_16_0_1_1479854184911_60300"> <font
id="yui_3_16_0_1_1479854184911_61028" size="3">><br
clear="none">
<span id="yui_3_16_0_1_1479854184911_60840">>That
"distinction" is meaningless and completely
useless. The idea that adding a ballot is
"something you did" that rates a mention is
ridiculous.</span></font></div>
<div class="yiv4410041191moz-cite-prefix"
id="yui_3_16_0_1_1479854184911_60300"
style="font-family: HelveticaNeue, "Helvetica
Neue", Helvetica, Arial, "Lucida
Grande", sans-serif;"><font size="3"><br>
</font></div>
<div class="yiv4410041191moz-cite-prefix"
id="yui_3_16_0_1_1479854184911_60300"
style="font-family: HelveticaNeue, "Helvetica
Neue", Helvetica, Arial, "Lucida
Grande", sans-serif;"><font
id="yui_3_16_0_1_1479854184911_60874" size="3">I'm
not sure about this specific example but I think
this kind of distinction could be a useful
defense. For IRV I might argue that a mono-raise
failure happens not just from raising the winner
but also <i
id="yui_3_16_0_1_1479854184911_62253">lowering</i> some
other, incidental candidate. The reason
mono-raise failures are offensive is that
supposedly the voter has done nothing but aid
the preexisting winner. But at least in IRV i</font><span
style="font-size: 16px;"
id="yui_3_16_0_1_1479854184911_60873">t is not
so clear as that.<br clear="none">
<br clear="none">
<blockquote type="cite"
id="yui_3_16_0_1_1479854184911_60311"><span
class="yiv4410041191"> </span></blockquote>
>Regarding MDDA, symmetrically completing
the ballots only at the bottom and having a
moveable approval cutoff fixes its failures of
Mono-add-Plump<br clear="none">
>and Plurality and Irrelevant Ballots
Independence and in my opinion makes it a
good/acceptable method.</span></div>
<div class="yiv4410041191moz-cite-prefix"
id="yui_3_16_0_1_1479854184911_60300"
style="font-family: HelveticaNeue, "Helvetica
Neue", Helvetica, Arial, "Lucida
Grande", sans-serif;"><span style="font-size:
16px;"><br>
</span></div>
<div class="yiv4410041191moz-cite-prefix"
id="yui_3_16_0_1_1479854184911_60300"
style="font-family: HelveticaNeue, "Helvetica
Neue", Helvetica, Arial, "Lucida
Grande", sans-serif;" dir="ltr"><span
style="font-size: 16px;"
id="yui_3_16_0_1_1479854184911_61103">Hmm, with
a movable cutoff MDDA already violates Plurality
with three candidates. Do you think
symmetric-completion of the bottom can save it?</span></div>
<div class="yiv4410041191moz-cite-prefix"
id="yui_3_16_0_1_1479854184911_60300"
style="font-family: HelveticaNeue, "Helvetica
Neue", Helvetica, Arial, "Lucida
Grande", sans-serif;" dir="ltr"><span
style="font-size: 16px;"><br>
</span></div>
<div class="yiv4410041191moz-cite-prefix"
id="yui_3_16_0_1_1479854184911_60300"
style="font-family: HelveticaNeue, "Helvetica
Neue", Helvetica, Arial, "Lucida
Grande", sans-serif;" dir="ltr"><span
style="font-size: 16px;"
id="yui_3_16_0_1_1479854184911_62843">For
whatever interest it may be, I calculated the
"DNA" for the method you describe and got the
exact same 343-digit code as for ICA(explicit).
That's the first time I've hit a method I
already had...<br clear="none">
<br clear="none">
Chris Benham<br clear="none">
</span></div>
<div class="yiv4410041191moz-cite-prefix"
id="yui_3_16_0_1_1479854184911_60300"
style="font-family: HelveticaNeue, "Helvetica
Neue", Helvetica, Arial, "Lucida
Grande", sans-serif;"><span style="font-size:
16px;"><br>
</span></div>
</div>
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