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<TITLE>Re: [Condorcet] Can we come to consensus?</TITLE>
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<DIV id=idOWAReplyText15227 dir=ltr><FONT size=2></FONT> </DIV>
<DIV dir=ltr><FONT size=2>Jeff wrote ...</FONT></DIV>
<DIV dir=ltr><FONT size=2></FONT><FONT size=2><BR>Now that we have presented a
few favorites and examined them, I hope we all<BR>at least understand each
other, even if we do not yet agree. It now looks<BR>like we have the
following:<BR><BR>* DMC has one ardent supporter and several contributors who
think it<BR>acceptable.<BR><BR>* Shulze (WV) is widely acceptable, already in
use, and hated by none.<BR><BR>* Smith//Approval is widely acceptable, but it
has a few detractors who<BR>sense burying.<BR><BR>I reply:</FONT></DIV>
<DIV dir=ltr><FONT size=2></FONT> </DIV>
<DIV dir=ltr><FONT size=2>Shulze and Smith//Approval have been around the
longest, so they are more widely known than DMC.</FONT></DIV>
<DIV dir=ltr><FONT size=2></FONT> </DIV>
<DIV dir=ltr><FONT size=2>But let's compare them head-to-head with
DMC.</FONT></DIV>
<DIV dir=ltr><FONT size=2></FONT> </DIV>
<DIV dir=ltr><FONT size=2>DMC is identical to Shulze when defeat strength is
measured by winning approval (instead of winning votes). The only
disadvantage of DMC in this comparison is that it requires an approval
cutoff. In all other ways, including ease of description, DMC
is as good or better than Shulze.</FONT></DIV>
<DIV dir=ltr><FONT size=2></FONT> </DIV>
<DIV dir=ltr><FONT size=2>In particular, because Shulze lacks approval
information it cannot take it into account. Because of this DMC tends
to pick a better winner than Shulze under zero-info sincere
voting.</FONT></DIV>
<DIV dir=ltr><FONT size=2></FONT> </DIV>
<DIV dir=ltr><FONT size=2>On the other hand, "winning approval" is a more robust
measure of defeat strength than "winning votes." Because of this fact,
Shulze is at least as vulnerable to strategical manipulation as DMC is. To
understand this better see the example I posted this morning to both
the Condorcet and the EM list. [It hasn't shown up yet on the Condorcet
list.]</FONT></DIV>
<DIV dir=ltr><FONT size=2></FONT> </DIV>
<DIV dir=ltr><FONT size=2>As in Smith//Approval the DMC winner always
comes from the Smith set. When the two methods choose different members of
the Smith set, DMC chooses the pairwise winner of the two, while Smith//Approval
chooses the one with the higher approval. So Smith//Approval favors
approval information over pairwise information compared to DMC.</FONT></DIV>
<DIV dir=ltr><FONT size=2></FONT> </DIV>
<DIV dir=ltr><FONT size=2>I would rather see plain old garden variety Approval
or Range(-1,0,1) than Smith//Approval, which seems like a cobbled together kluge
in comparison with DMC.</FONT></DIV>
<DIV dir=ltr><FONT size=2></FONT> </DIV>
<DIV dir=ltr><FONT size=2>Also, as has been pointed out, the Smith//Approval
winner X can lose pairwise to the Smith//Approval runner up Y.
In other words it can happen that in a runoff between the winner X and
the candidate Y who would have won had the winner dropped out, this
candidate Y would win.</FONT></DIV>
<DIV dir=ltr><FONT size=2></FONT> </DIV>
<DIV dir=ltr><FONT size=2>DMC is not afflicted by this problem.</FONT></DIV>
<DIV dir=ltr><FONT size=2></FONT> </DIV>
<DIV dir=ltr><FONT size=2>The perception that Shulze is more widely acceptable
than DMC may be an illusion due to the fact that members who have not weighed in
on this issue consider the 15 reasons to be so definitive as to
make the conclusion obvious.</FONT></DIV>
<DIV dir=ltr><FONT size=2></FONT> </DIV>
<DIV dir=ltr><FONT size=2>In my opinion the best
Condorcet proposal is DMC. I suspect that a majority of members
who have read the fifteen reasons would agree.</FONT></DIV>
<DIV dir=ltr><FONT size=2></FONT> </DIV>
<DIV dir=ltr><FONT size=2>However, if there is no simple ballot option for the
voters who don't want to rank the candidates, i.e. for those voters that would
rather delegate that task to their favorite, then in that
case Approval is a better public proposal.</FONT></DIV>
<DIV dir=ltr><FONT size=2></FONT> </DIV>
<DIV dir=ltr><FONT size=2>Peace,</FONT></DIV>
<DIV dir=ltr><FONT size=2></FONT> </DIV>
<DIV dir=ltr><FONT size=2>Forest</FONT></DIV>
<DIV dir=ltr><FONT size=2></FONT> </DIV>
<DIV dir=ltr><FONT size=2></FONT> </DIV>
<DIV dir=ltr><FONT size=2></FONT> </DIV>
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