[EM]

[MIKE OSSIPOFF]

>, 14 Mar 2001 00:18:36 -0000
>"MIKE OSSIPOFF" <nkklrp at hotmail.com> wrote:
>
> > You probably know this already, but it's often said that, if
> > the important output is an ordering of the candidates, then
>Tideman's
> > method is best. If considerations about the output ranking are
> > more important than SSD's or BeatpathWinner's advantages.
>
>I find it rather peculiar to imagine that the best ordering of the
>candidates doesn't put the best candidate at the top.  That seems to
>be what you're saying.

We've been over this amply on EM. To some people, for some purposes, certain 
consistency
properties of the overall output ordering are more important than
the advantages of SSD & BeatpathWinner in regards to the 1st choice.
But that could only be important if the important output of the voting
system were a complete output ranking, and if we wanted it to have
the consistency properties that Blake & Steve Eppley have described
for Tideman.


>
> > A brief wording of Tideman:
> >
> > Drop the strongest defeat that's the weakest defeat in a cycle.
> > Repeat till there are no cycles. At that time, any candidate with
> > no undropped defeats wins.
>
>My preferred definition is as follows:
>
>Ranked Pairs gives the ranking of the options that always reflects
>the majority preference between any two options, except in order to
>reflect majority preferences with greater margins.
>
>I suspect Mike prefers his definition.  I suspect arguing the point
>would be futile.

It would be futile & silly to argue about which of 2 valid definitions
we prefer. If your definition doesn't really define the same method
that Tideman's instruction defines, that would be another matter.

It isn't so much a matter of what I or you prefer. I too looked for
a briefer, simpler definition like the one you wrote above. I don't
know of one that's valid. Besides, your definition sounds more like
a statement of goals than an instruction. Your definition doesn't
say anything about the number of defeats that are dropped. I don't know
if your definition is a correct definition of Tideman's method. I'll
comment later or tomorrow if at that time I can say for sure.

>
> > [end of definition]
> >
> > I've heard that Tideman can become a bit awkward when pairwise ties
> > & equal defeats are likely, which is how it is when there aren't
> > lots of voters.
>
>I'd have to know exactly what is meant here in order to respond.
>Writing an implementation is made much more difficult by the
>possibility of ties, but I've already written an implementation.

Norm can tell you more about that.

>
> > The preferred version of Tideman's method on this list is the
> > version that measures the strength of a defeat by the support of
> > that defeat--the number of people voting for that pairwise defeat.
> > Defeat-support, as opposed to margins (defeat support minus defeat
> > opposition). Tideman himself used margins. Defeat-support gives us
> > compliance with important strategy criteria.
>
>I prefer margins as well.  It's important to recognize that just
>because Mike posts a lot, this doesn't make his views official.

Thank you for telling us that important thing to recognize. But,
whereas you call your website an EM resource, I've never said that
my views are official. However, I do believe that I speak for a majority
of Condorcetists on this list when I say that a majority prefer
defeat-support rather than margins.

As for my statement about strategy criteria, I don't know how "official"
would apply to that. Our choice of criteria depends on what standards we
value, and I there aren't "official" standards. The standards of
majority rule & getting rid of the lesser-of-2-evils problems are
very widely agreed-on, but I'm not saying you're wrong if you don't
value those standards.


>
>I've created a web page that argues for margins:
>http://www.fortunecity.com/meltingpot/harrow/124/path/inc.html
>
> > I believe that, when considerations related to an output ordering
> > aren't the most important, BeatpathWinner, and its equivalent,
> > Cloneproof SSD, and SSD, are more preferred on this list.
>
>At least he's undecided on this point.

Norm, Markus, and I have said we prefer BeatpathWinner/Cloneproof SSD
to Tideman. You alone prefer Tideman. Steve Eppley has left the list,
for the time being at least. With Steve, it's 3 to 2. Without Steve
it's 3 to 1, among those who have expressed a preference on EM.

Likewise, you're the only one who advocates on EM or at a website, for
margins, as opposed to defeat-support.

I'd actually be interested to
>know how others feel.

Yes, that's why I suggested that the demonstration poll be about
voting systems.

My general impression is that most active
>posters to the list aren't even interested in this debate, but I could
>be wrong.

You, I, Norm, and Markus have expressed opinions on those 2 issues on
EM.

>>Also, unless you're Mike Ossipoff, please call Tideman's method
>"Ranked Pairs".  That's the name Tideman himself gave the method.

I wouldn't have thought that what name to use is important enough to
beg about.

Mike Ossipoff

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