[EM] Who first proposed wv Condorcet

[MIKE OSSIPOFF]

Someone asked:

you wrote (25 Feb 2005):
>I know Mike Ossipoff advocates WV as opposed to WM for
>the completion of methods such as Ranked Pairs, Schulze,
>etc. Was he actually the first person to come up with
>the idea as the sentence above seems to imply?

Markus replied:

As far as I remember correctly, two different approaches
have been discussed at this mailing list.

First approach: Mike Ossipoff suggested that when a given
voter strictly prefers candidate A to candidate B then this
voter "approves" candidate A and "rejects" candidate B. In
the archives of this mailing list, Mike calls a candidate B
"majority rejected" or "majority beaten" when there is a
candidate A such that a majority of the voters strictly
prefers candidate A to candidate B. Mike always said that
"majority rejected" candidates shouldn't be elected.

In my opinion, this approach is very problematic because
it isn't clear how it can be generalized to other election
methods than MinMax.

I reply:

The name "Min-Max" is used to refer to several different methods. That means 
that it isn't a very useful name for a method. One of the methods often 
designated by "Min-Max" is PC, Plain Condorcet, a wv method. Maybe that's 
the Min-Max that Markus is referring to.

About applicability to methods other than PC, Markus has a point: Say the 
Smith set candidates all have majority defeats against eachother, but 
someone outside the Smith set has no majority defeat. Markus's majority 
beatpath is a way to define a kind of majority rule that avoids that 
problem. I have nothing against that.  In fact I posted here a definition of 
majority rule that's somewhat similar to Markus's majority beatpaths. There 
was some small difference, and when I posted my majority rule definition, I 
told why I prefer it to Markus's majority beatpaths.

I use my definition of majority rule as a supporting definition for my 
definition of defensive strategy.
(My definition of defensive strategy refers to majority rule).

I'll complete this reply, and then post my definition of majority rule 
later. Maybe immediately, maybe tomorrow. Hopefully no later than tomorrow.

Markus continues:

As far as I know, Mike still uses this approach. See e.g.:
http://lists.electorama.com/pipermail/election-methods-electorama.com/2004-May/013047.html

Second approach: The second approach says that when some
voters cast only a partial ranking (because of strategic
considerations or other reasons) then the effect of this
behaviour should be as small as possible.

I reply:

With wv Condorcet, truncation is less able to cause a majority rule 
violation, in the sense that we all mean "majority rule".

Markus continues:

For example, in 1997 I proposed the following criterion
("majority beatpath criterion"):

   "X >> Y" means that a majority of the voters strictly
   prefers candidate X to candidate Y.

   A "majority beatpath" from candidate X to candidate Y
   is an ordered set of candidates Z(1),...,Z(n) with the
   following properties:

      1. Z(1) is identical to X.
      2. Z(n) is identical to Y.
      3. Z(i) >> Z(i+1) for all i = 1,...,(n-1).

   If there is a majority beatpath from candidate A to
   candidate B and no majority beatpath from candidate B
   to candidate A, then candidate B must be elected with
   zero probability.

I reply:

My definition of majority rule is similar, but not identical, to that.

Markus continued:

As far as I remember correctly, it was me (and not Mike
Ossipoff) who suggested that "winning votes" should be
used for the Schulze method

I reply:

But he didn't ask who first defined the Schulze method. He asked who first 
proposed the wv Condorcet methods.

I'd proposed the wv Condorcet methods, and wv Condorcet methods were 
popular,  long before you joined EM, and long before you defined Schulze's 
method and made it a wv method.

Mike Ossipoff

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