[EM] Approval/Condorcet

[Forest Simmons]

I agree with Russ that Kevin's Approval Runoff method (eliminate lowest 
approval candidates until there is a CW) is a decent public proposal.

It would be interesting to compare that method with what I call TACF, 
Total Approval Chain Filling:

Proceeding from the highest approval candidate to the lowest approval 
candidate, fit as many as possible into a chain totally ordered by 
pairwise defeat.  The candidate that beats all of the others in this chain 
wins the election.

The two methods always agree when there are only three candidates, since 
they both pick the CW when there is one, and both eliminate the lowest 
approval candidate when there is no CW.

TACF always picks a member of the Banks set. It seems improbable that 
Kevin's version of Approval Runoff always picks from Banks.

Both methods are monotone and clone proof.

I think they both satisfy Independence from Pareto Dominated Alternatives, 
at least when approval ties are broken appropriately.

Bye For Now,

Forest