Chris Benham chrisjbenham at optusnet.com.au
Mon Mar 12 09:29:02 PDT 2007

Jobst Heitzig wrote:

>Def. DAMC (Definite Absolute Majority Choice):
>Make a list of absolute majority size pairwise defeats. 
>  Process this list in order of descending approval score of the 
>defeating option. Keep the defeat at hand iff (i) the defeated option 
>is not already defeated by the kept defeats and (ii) the new defeat 
>does not build a cycle with those defeats already kept. 
>  From those options not defeated in the end, elect the most approved 
>In other words: We use River with 
>  defeat := absolute majority size defeat
>  defeat strength := approval score of defeating option
>and resolve the remaining ambiguity by Approval.
>I'm pretty sure that this method has the following properties:
>- monotonicity
>- clone-proofness
>- IPDA and ISDA
>- immunity from absulute majority complaints (in the above sense)
>- immunity from 2nd place complaints
>- the winner is never defeated with absolute majority by a more approved 
>option or by the most approved contender.
>What I'm not sure about so far is whether using Beatpath or Ranked Pairs 
>instead of River gives the same winner, and what would happen when we 
>used the "resorting" or the "definitively defeated" version of DMC with 
>absolute majority size defeats only.

Does this meet FBC/SF? 

Because I think something that fails Condorcet and  Irrelevant Ballots 
and presumably Definite
Majority would want to.

Chris Benham


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