[EM] Borda Done Right

Kevin Venzke stepjak at yahoo.fr
Wed Dec 2 21:16:21 PST 2020

Hi Forest, these are interesting... I have a new rank ballot sim currently and that Copeland one seems like an interesting one to try. Do you think it's actually cloneproof? Clearly if a faction tries to flood the race with additional candidates, the total score they can achieve across all those candidates should stay constant.

Kristofer has been studying low-manipulability methods where, often, observing the first preference count is a key component. So I wonder if the decloned Copeland would end up with similar properties.

I have a method similar to your DSV approval method. My primary issues (differences?) are just that I don't think truncated rankings can be allowed, and that I don't really see it as a single-round method. Very minor issues. I think this method gives strange results, but has its place. It doesn't feel to me like an automated approval method, but a method that forces voters to provide approval to enough candidates to represent a majority of the voters. Since this resembles proposing a coalition to govern, I have just been calling this "the coalition method."


Le mercredi 2 décembre 2020 à 18:04:50 UTC−6, Forest Simmons <fsimmons at pcc.edu> a écrit : 

>It is a very small step from Copeland done right to Borda done right because in a certain sense Borda can be 
>thought of as Copeland applied to each ballot separately and then summed over ballots. 
>Let's start with Copeland and change it into Borda.
>Copeland: The score of alternative X is the total probability of the alternatives beaten pairwise by X minus the 
>total probability of the alternatives that beat X pairwise.
>Borda: The contribution of ballot B to the Border score by alternative X is the total probability of the alternatives 
>ranked below X on B minus the total probability of the alternatives ranked above X on ballot B.
>That's it!
> What do you think?

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