[EM] Uncovered set methods (Re: How close can we get to the IIAC)

[Kristofer Munsterhjelm]

fsimmons at pcc.edu wrote:

> By the way, (contrary to Marcus' confusion) UncAAO does satisfy  Monotonicity,
> Clone Independence, IDPA, and Independence from Non-Smith Alternatives, as well
> as the following:
> 
> 1.  It elects the same member of a clone set as the method would when restricted
> to the clone set.
> 
> 2.  If a candidate that beats the winner is removed, the winner is unchanged.
> 
> 3.  If an added candidate covers the winner, the new candidate becomes the new
> winner.
> 
> 4.  If the old winner covers an added candidate, the old winner still wins.
> 
> 5.  It always chooses from the uncovered set.
> 
> 6.  It is easy to describe:  Initialize L to be an empty list.  While there
> exists some alternative that covers every member of L,  add to L the one (from
> among those) ranked on the greatest number of ballots.  Elect the last candidate
> added to L. 
> 
> What other deterministic method (based on ranked ballots with truncations
> allowed) satisfies all of these criteria?

River is the only (other) method I know of that meets Monotonicity, 
clone independence, IPDA, and independence from non-Smith alternatives. 
It's "simple" (affirm defeats that do not create a cycle or a 
branching), but as for whether it meets the other criteria, I do not know.

River also satisfies something Jobst called "independence of strongly 
dominated alternatives", which is stronger than IPDA. It's defined here: 
http://lists.electorama.com/pipermail/election-methods-electorama.com/2004-October/014018.html