[EM] D2MAC can be much more efficient than Range Voting (corrected)

Warren Smith wds at math.temple.edu
Wed Mar 7 14:28:41 PST 2007

> Recall that in D2MAC you specify a favourite and as many "also approved"
> options as you want. Then two ballots are drawn and the winner is the
> most approved option amoung those that are approved on both ballots
> (if such an option exists), or else the favourite option of the first
> ballot.
> If voters are sincere, the result will be this:
>   55%: favourite A, also approved C
>   45%: favourite B, also approved C
> Winner: C

And you answered: 
> --WDS correction: actually, it appears to me that the winner is
> A with probability 30.25%
> B with probability 20.25%
> C with probability 49.50%
> with social average utility = 7.03

That's definitely wrong: No matter what two ballots are drawn, both approve of C
and C is the most approved option. Hence C is elected with certainty.

--WDS: Huh?
So suppose both ballots are "favorite A, also approved C."

Are you claiming C wins with certainty???


More information about the Election-Methods mailing list