[EM] more Condorcet mythology and other information

[Warren Smith]

>Benham: Moulin's proof (by Schulze)
--WDS: Thank you.  (I had already put this proof, credited to Schulze,
in my own paper last year, with his permission.)
I note that this proof works regardless of
whether rank-equalities are permitted in the Condorcet ballots.
It shows voting honestly can hurt you (versus not voting at all)
in every Condorcet system.

>Ritchie:
Strategy in Condorcet... order reversal?

--WDS:
There seems to be the idea in either Ritchie's or other minds
that, if you allow equalities in rankings in a Condorcet voting systems 
(and/or, handle them via "winning votes")
then "order reversal" will not be required of a strategic voter.

I believe that idea is false.  I suspect that in every Condorcet system, whether
rank-equalities are allowed or not, and whether "winning-votes" are used or not,
there are election situations where you (a voter or co-feeling small bloc
of voters) must cast a vote which
is fully-dishonest about one or more orderings, i.e in which you say A>B
when you honestly feel B>A.  If you do not do this in your vote,
then you get a worse election winner.

One way to set up such a situation (which should work against most of
the Condorcet systems discussed on EM) is this.
You honestly feel A>C>the other candidates.
If you do nothing or vote honestly, then C will be the Condorcet winner.
If you vote A>the others>C  then C will no longer be
the Condorcet winner allowing A to win.
If you rank the others EQUAL to C then C will still be the Condorcet winner.

>Ossipoff: ...elections in which equal ranking is disallowed. Of course
no one is proposing such a version of Condorcet.
--WDS: Tideman in his 2006 book recommends exactly that.
Just because the most recent and important book in an area recommends something, does 
that mean  that Ossipoff should retreat one iota from his stance that "no one" does?


>WDS: In IEVS, presently, equal rankings are forbidden in rank-order
>methods.
>M.Ossipoff: which (like Warren's other assumptions) makes the results
meaningless.
>WDS: I do not agree I ever made any "assumption" here.
>M.O.: If you didn't assume or believe the premises you based your simulation
on, then even you must not have believed that your simulation's results
would have any relevance to real-world elections. Shall we call them
simulation-premises instead of assumptions then, to avoid any
speculation  about what you were thinking? ...if your simulation
is based on counterfactual premises, then its results won't mean anything.

--WDS: I did not make this "assumption." I did not "base my simulation
on" it.  I did not make these "premises."  I did not make these
"simulation-premises."  It would indeed be good if you avoided
speculation about what I think.  Or even worse, what everybody thinks.
If you must make such speculations, please label them as speculations, not
as certainties.

Warren D Smith
http://rangevoting.org