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<p><font size="4"><br>
It is very difficult (if not impossible) to modify IRV without
causing it to lose some criterion compliance <br>
that a lot of its supporters like. This is part of the case
that it is in its way a good method, certainly compared<br>
to STAR. <br>
<br>
</font></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;"><font size="4">49 A
24 B
27 C>B|
Here, with the C>B voters extending their approval to B, the winner in this suggested
"approval-enhanced" method is B.
But plain IRV meets Later-no-Harm, which a lot of people like. In this example if the
24 B voters change to B>C (even without approving C) then the winner would change from B to C,
breaking LNHarm.
</font></pre>
<font size="4">
</font>
<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;"><font size="4">49 A
24 B>C
27 C>B|</font></pre>
<font size="4">
</font>
<p><font size="4">Now the new IRV winner is C and C also now
pairwise beats both the other candidates.<br>
<br>
I am sure that a more complicated example could be found that
demonstrates that it also fails Later-no-Help, so maybe Toby<br>
was right in calling this a "kludge" after all.<br>
<br>
Chris Benham<br>
</font><br>
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<blockquote type="cite">
<h1 style="color: rgb(0, 0, 0); font-family: "Times New
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initial; text-decoration-color: initial;">[EM]
Approval-enhanced IRV (take 2)</h1>
<b style="color: rgb(0, 0, 0); font-family: "Times New
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text-decoration-style: initial; text-decoration-color:
initial;">C.Benham</b><span style="color: rgb(0, 0, 0);
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initial; text-decoration-color: initial; display: inline
!important; float: none;"><span> </span></span><a
href="mailto:election-methods%40lists.electorama.com?Subject=Re%3A%20%5BEM%5D%20Approval-enhanced%20IRV%20%28take%202%29&In-Reply-To=%3C9fed1bfa-1ee8-cb6c-8e85-e394d3eb898f%40adam.com.au%3E"
title="[EM] Approval-enhanced IRV (take 2)"
style="font-family: "Times New Roman"; font-size:
medium; font-style: normal; font-variant-ligatures: normal;
font-variant-caps: normal; font-weight: 400; letter-spacing:
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text-transform: none; widows: 2; word-spacing: 0px;
-webkit-text-stroke-width: 0px; white-space: normal;">cbenham
at adam.com.au</a><br style="color: rgb(0, 0, 0); font-family:
"Times New Roman"; font-size: medium; font-style:
normal; font-variant-ligatures: normal; font-variant-caps:
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<i style="color: rgb(0, 0, 0); font-family: "Times New
Roman"; font-size: medium; font-variant-ligatures:
normal; font-variant-caps: normal; font-weight: 400;
letter-spacing: normal; orphans: 2; text-align: start;
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text-decoration-style: initial; text-decoration-color:
initial;">Mon Aug 21 09:36:20 PDT 2023</i><span style="color:
rgb(0, 0, 0); font-family: "Times New Roman";
font-size: medium; font-style: normal; font-variant-ligatures:
normal; font-variant-caps: normal; font-weight: 400;
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word-spacing: 0px; -webkit-text-stroke-width: 0px;
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text-decoration-thickness: initial; text-decoration-style:
initial; text-decoration-color: initial; display: inline
!important; float: none;"></span>
<p style="color: rgb(0, 0, 0); font-family: "Times New
Roman"; font-size: medium; 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;
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<ul style="color: rgb(0, 0, 0); font-family: "Times New
Roman"; font-size: medium; font-style: normal;
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<li><br>
</li>
</ul>
<hr style="color: rgb(0, 0, 0); font-family: "Times New
Roman"; font-size: medium; 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;
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<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;"><font size="4">This is I think more appealing and streamlined than my earlier version.
*Voter strictly rank from the top however many candidates they wish.
Also they can mark one candidate as the highest ranked candidate they
approve.
Default approval is only for the top-ranked candidate.
Determine the IRV winner.
On ballots that approve the IRV winner, approval for any candidate or
candidates ranked below the IRV winner is withdrawn.
Elect the pairwise winner between the (thus modified) approval winner
and the IRV winner.*
This works fine in the same way as the earlier version in the example
given to talk about Minimal Defense and Chicken Dilemma.
It is more Condorcet efficient than normal IRV, and meets (or comes close enough to meeting)
appropriately modified versions of the LNHs and Minimal Defense and Chicken Dilemma.
49 A (sincere might be A>B)
24 B (sincere might be B>C)
27 C>B
If the C voters B>A preference is strong they can by approving B avoid
regret for not Compromising.
Then the final pairwise comparison will be between B and A and B will win.
Chris Benham</font></pre>
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