[EM] Equal defeats in RP(m)?

[Blake Cretney]

On Tue, 01 May 2001 07:24:42 -0000
"MIKE OSSIPOFF" <nkklrp at hotmail.com> wrote:

> Someone has designated Ranked Pairs(margins), and so it's necessary
> to ask for a complete definition of it. In particular, how exactly
> does it deal with equal defeats, in all the kinds of situations
> in which they can occur and in all the procedural questions they can
> raise in an RP(m) count?
>
> Obvioiusly it would be inappropriate for that definition to be
> supplied after the ballots are posted.

I've been assuming that no specific tie-breaker is proposed for the
purposes of this election.  Unless I'm mistaken, that is the case for
most of the methods suggested.  For example, IRV, plurality, Approval,
etc.

Personally, I recommend the tiebreaker Zavist and Tideman give, and
which I described recently.  However, most of the people who will vote
have already voted, so it's a little late to add to the proposal.

I should point out that most cases of equal defeats won't affect the
result, and that it isn't hard to write a program which detects these
cases (or at least the common ones).  In fact, I've written such a
program.

---------------------------------------------------------------------
Blake Cretney   http://www.fortunecity.com/meltingpot/harrow/124/path

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. 
(B. T. Zavist & T. Tideman, "Complete independence  of clones in the 
ranked pairs rule", Social choice and welfare, vol 6, 167-173, 1989)