[EM] IRV completed pairwise-count example

MIKE OSSIPOFF nkklrp at hotmail.com
Mon Jul 1 18:45:17 PDT 2002

First of all, I call it pairwise-count, because "Condorcet" properly
applies to Condorcet's own proposals for solving circular ties.

IRV-completed pairwise-count has been proposed many times. Here's an

3 candidates: A, B, & C.

Sincere rankings:

40: ABC
25: BAC
35: CBA

Voted rankings:

40: A
25: BA
35: CB

The A voters, the ones who are in a position to make a strategic
circular tie, are also the ones who win that tie.

What does it take to keep A from winning? Truncation by the B voters
won't do it. The C voters could rank B equal to C, something that they
wouldn't have to do in the Condorcet(wv) versions. That's a general
pairwise-count defensive strategy that works against offensive truncation, 
but not against offensive order-reversal.

If the A voters used offensive order-reversal, as margins advocates
say they should, then the only defensive strategy that the C voters
have is to vote B over C.

IRV-completed pairwise-count doesn't offer any improvement over
the general pairwise-count defensive strategies. All the strategy
criticisms of pairwise-count methods, from Approval advocates and
IRV advocates, apply fully to IRV-completed pairwise-count, and to
the margins "Condorcet" versions.

The use of a pairwise-count methods gains compliance with Condorcet's
Criterion, but, as the example shows, Condorcet's Criterion isn't
worth a lot by itself.

Mike Ossipoff

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