[EM] Proposal: Majority Enhanced Approval (MEA)

[Juho]

You seem to use implicit approval cutoff at the end of the ranked  
candidates (since you say "based on ranked ballots with truncations  
allowed"). How about using explicit cutoff? Would that take away  
something essential? I'd like the left wing voters rank also the right  
wing candidates and vice versa. Otherwise we might easily lose a  
sincere Condorcet winner.

Juho



On May 8, 2010, at 9:32 PM, fsimmons at pcc.edu wrote:

> I have a proposal that uses the same pairwise win/loss/tie  
> information that Copeland is based on, along with
> the complementary information that Approval is based on.  It’s a  
> simple and powerful Condorcet/Approval
> hybrid which, like Copeland, always elects an uncovered candidate,  
> but without the indecisiveness or clone
> dependence of Copeland.
>
> I used to call it UncAAO, but for better name recognition, I’m  
> changing the name to Majority Enhanced
> Approval (MEA).
>
> The method is extremely easy to understand once you get the simple  
> concept of covering.  Candidate X
> covers candidate Y if candidate X pairwise beats both Y and every  
> candidate that Y beats pairwise.
>
> MEA elects the candidate A1 that is approved on the greatest number  
> of ballots if A1 is uncovered.
> Otherwise it elects the highest approval candidate A2 that covers A1  
> if A2 is uncovered.  Otherwise it elects
> the highest approval candidate A3 that covers A2 if A3 is  
> uncovered.  Otherwise, etc. until we arrive at an
> uncovered candidate An, which is elected.
>
> MEA satisfies Monotonicity, Clone Independence, Independence from  
> Pareto Dominated Alternatives, and
> Independence from Non-Smith Alternatives, as well as all of 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) with the  
> greatest approval.  Elect the last
> candidate added to L.
>
> What other deterministic method (based on ranked ballots with  
> truncations allowed) satisfies all of these
> criteria?
>
> Forest
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