[EM] Markus reply

[Russ Paielli]

Markus Schulze markus.schulze-at-alumni.tu-berlin.de |EMlist| wrote:
> Dear Russ,
> 
> I interpret Mike Ossipoff's "Strategy-Free Criterion" (SFC)
> and "Generalized Strategy-Free Criterion" (GSFC) as follows:
> 
> "X >> Y" means that a majority of the voters strictly prefers
> candidate X to candidate Y.
> 
> SFC: Suppose (1) A >> B and (2) the partial individual
> rankings can be completed in such a manner that candidate A
> is a Condorcet candidate. Then candidate B must be elected
> with zero probability.

I think you are trying to convert what I call a "Mike-style" criterion 
into a "normal" criterion. Let me repeat a portion of what I wrote 
yesterday:

-------------------------------------------------

What we have here, it seems to me, is confusion cause by a failure to 
distinguish between two fundamentally different classes of criteria. 
Consider the basic voting process. It starts with the voters' true 
preferences, then the votes are cast, then the votes are tallied and the 
winner is determined:

true preferences --> votes cast --> winner determined

Let's call the process represented by the first arrow the "voting 
strategy" and the process represented by the second the "tally rules."

All voting system criteria that I have ever seen, excluding those that 
originated with Mike, involve the tally rules only. They consider only 
the votes cast and make no reference whatsoever to the true preferences 
of the voters.

At some point Mike came along and changed the paradigm fundamentally, 
probably without ever explaining that he was doing so. Naturally, this 
causes confusion. To minimize the confusion, I suggest we distinguish 
between "normal" criteria and "Mike-style" criteria.

--------------------------- end of repeated text

You seem to be trying to interpret SFC in terms of the tally rules only, 
but you can't do that because, unlike "normal" criteria, it involves the 
voting strategy too.

In your interpretation of SFC above, I think your supposition 2 should 
actually be part of the result. Here is my attempt at it:

SFC: Suppose A >> B. Then partial individual rankings can be completed 
in such a manner that no preferences are reversed and candidate B must 
be elected with zero probability.

--Russ