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As asked for: a link to SPPA paper presented at Chicago in April 2007.<br>
<a class="moz-txt-link-freetext" href="http://convention2.allacademic.com/one/mpsa/mpsa07/index.php?click_key=1&PHPSESSID=a6f3cb6bdfc80d157cec9e6b5ffc0add">http://convention2.allacademic.com/one/mpsa/mpsa07/index.php?click_key=1&PHPSESSID=a6f3cb6bdfc80d157cec9e6b5ffc0add</a><br>
IRV is the single winner method used as engine to determine the support
for each candidate in this case.<br>
<br>
Steve Eppley a écrit :
<blockquote cite="mid4769CFEA.3010700@alumni.caltech.edu" type="cite">
<pre wrap="">Hi,
It was not that I didn't read the rest of Stephane's earlier message.
It was his lack of clarity: His next example looked like he switched to
a different voting method, because his description of the tallying was
very different and he did not indicate he was using the same method
("Repetitive Condorcet (Ranked Pairs (Winning Votes)) Elimination.").
At this point, I will assume Stephane does not intend to provide a
definition of that voting method nor a link to it, and I don't have time
to hunt in older messages to see if it was defined once upon a time.
Regards,
Steve
-------------
Stéphane Rouillon wrote:
</pre>
<blockquote type="cite">
<pre wrap="">My advice to Steve is to read all an email before comments.
Cut-off were applied further building the counter-example in the part
he snipped...
Of course without cut-off, the original ordering method comes back.
"meaningless winners which could not get elected with SPPA in the end."
refers to the fact that the multiple-winner method will not
necessarily elect a candidate that received the most support
in a district. Again, it is a matter of considering an election as a
representative exercise and not as a battle.
Stéphane Rouillon
Steve Eppley a écrit :
</pre>
<blockquote type="cite">
<pre wrap="">Hi,
Stéphane's latest example (immediately below) is very different from
his earlier example that I quoted (further below) which he tallied
using a voting method he called "Repetitive Condorcet (Ranked Pairs
(Winning Votes)) Elimination." His earlier example had no "approval
cutoffs" and his latest example appears to have no connection to
Ranked Pairs or Condorcet. Thus he hasn't provided a basis for
claiming my comment was wrong.
My advice to Stéphane for when he sobers up (just joking) is to
reread his earlier example and then provide a clear definition of the
"Repetitive Condorcet (Ranked Pairs (Winning Votes)) Elimination"
method, or a link to its definition, so we will know what voting
method he was writing about. Based on the name he gave it and from
his earlier example, it appears (to me, at least) to be the method
that iteratively eliminates the candidate ranked last by MAM until
one remains.
The thrust of my comment was that since MAM satisfies Peyton Young's
LIIA criterion, it follows that MAM elects the same candidate as the
more complex voting method that iteratively eliminates the candidate
ranked last by MAM until one candidate remains. Was Stéphane
claiming this is wrong, when he wrote that my comment was wrong?
Second, I do not understand what he meant where he wrote,
"meaningless winners which could not get elected with SPPA in the
end." I suspect it is not relevant to the comment I made.
--Steve
---------------------------------
Stéphane Rouillon wrote:
</pre>
<blockquote type="cite">
<pre wrap="">First Steve's comment is wrong as shown below: A > B > C.
</pre>
<blockquote type="cite">
<pre wrap="">33: A > B | C
31: B > C | A
33: C | A > B
3: B | A > C
C is eliminated with 33 votes as support.
B is eliminated with 34 votes as support.
A is last eliminated but receives no rallying voters and finishes
with 33
votes as support.
B wins.
</pre>
</blockquote>
<pre wrap="">Second, as written before, scores or supports matter, not
meaningless winners which could not get elected with SPPA in the end...
S.Rouillon
Steve Eppley a écrit :
</pre>
<blockquote type="cite">
<pre wrap="">Hi,
Assuming I'm correctly understanding a voting method Stéphane
Rouillon used in a recent message (excerpted below), which he
called "Repetitive Condorcet (Ranked Pairs(Winning Votes))
elimination," it is unnecessarily complicated because it chooses
the same winner as Ranked Pairs(Winning Votes), which of course is
simpler.
Ranked Pairs(Winning Votes), also known as MAM, satisfies H Peyton
Young's criterion Local Independence of Irrelevant Alternatives
(LIIA). One implication of LIIA is that elimination of the
last-ranked candidate(s) does not change the ranking of the
remaining candidates.
By the way, a different criterion has been masquerading as LIIA in
Wikipedia. Peyton Young defined the real LIIA in his 1994 book
Equity In Theory And Practice (if not earlier).
--Steve
--------------------------------------
Stéphane Rouillon wrote:
-snip-
</pre>
<blockquote type="cite">
<pre wrap="">Let's try a counter-example:
3 candidates A, B, C and 100 voters.
Ballots:
35: A > B > C
33: B > C > A
32: C > A > B
Repetitive Condorcet (Ranked Pairs(winning votes) ) elimination
would produce
at round 1:
68: B > C
67: A > B
Thus ranking A > B > C
C is eliminated.
at round 2:
67: A > B is the ranking
B is eliminated
at round 3:
A wins.
</pre>
</blockquote>
<pre wrap="">-snip-
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