[EM] This might be the method we've been looking for:

fsimmons at pcc.edu fsimmons at pcc.edu
Fri Dec 2 16:12:23 PST 2011


Here’s a method that seems to have the important properties that we have been worrying about lately:

(1)	For each ballot beta, construct two matrices M1 and M2:
In row X and column Y of matrix M1, enter a one if ballot beta rates X above Y or if beta  gives a top        
rating to X.  Otherwise enter a zero.
IN row X and column y of matrix M2, enter a 1 if y is rated strictly above x on beta.  Otherwise enter a 
zero.

(2)	Sum the matrices M1 and M2 over all ballots beta.

(3)	Let M be the difference of these respective sums
.
(4)	Elect the candidate who has the (algebraically) greatest minimum row value in matrix M.

Consider the scenario
49 C
27 A>B
24 B>A
Since there are no equal top ratings, the method elects the same candidate A as minmax margins 
would.

In the case 
49 C
27 A>B
24 B
There are no equal top ratings, so the method gives the same result as minmax margins, namely C wins 
(by the tie breaking rule based on second lowest row value between B and C).

Now for
49 C
27 A=B
24 B
In this case B wins, so the A supporters have a way of stopping C from being elected  when they know 
that the B voters really are indifferent between A and C.

The equal top rule for matrix M1 essentially transforms minmax into a method satisfying the FBC.

Thoughts?



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