[EM] MinMax Opposition

John Karr brainbuz at brainbuz.org
Sun Nov 1 21:51:08 PST 2020

I've seen very little written about the MinMax Pairwise Opposition 
Method. Which is surprising, given that it is the only Later Harm Safe 
RCV method other than IRV (that I'm aware of).

It counts the votes against each choice and elects the choice that had 
the lowest opposition in its worst pairing.

It appears to agree with Condorcet more often than IRV does and handle 
Clones much better than IRV. Its' weakness is that it fails the 
Plurality and Condorcet Loser Criterion.

The obvious fixes involve pairing it with other methods such as 
restricting it to Smith Set when there is no Condorcet Winner (only 
helpful when there is no Condorcet Winner) or having a Runoff of the IRV 
Winner vs the MMPO winner, both of which introduce some later harm 
potential. Or alternately Dropping all choices lower in approval than 
the first choice votes for the plurality leader (while fixing Plurality 
it does not guarantee to eliminate the Condorcet loser) also introduces 
a later harm concern.

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