[EM] Paper By Ron Rivest (fsimmons at pcc.edu)

[Kristofer Munsterhjelm]

fsimmons at pcc.edu wrote:
> As I mentioned in my last message, Designated Strategy Voting  (DSV)
> methods almost always fail monotonicity, even when the base method is
> monotone.  I promised that I would give a general technique for 
> resolving this technique.
> 
> Before I try to keep that promise, let’s think about why DSV is such
> an attractive idea.  I think that there are two main reasons.  (1)
> The DSV “machine” is supposed to implement near optimal strategy for
> the voter based on the information it receives.  (2) The information
> the machine receives is directly from the voters on election day, so
> it should be more accurate than any politically manipulated polling
> (dis)information available to the voters as a basis for forming their
> own strategies, should they be so inclined.

Myself, I think the reasons that make DSV appealing is:
1. The machine can strategize better than the manual strategists, and it 
does so indiscriminately, so there's a leveling effect.
2. The machine can strategize better than the manual strategists but 
GIGO still applies, so there's an incentive to provide honest inputs.

They may be similar to your points, but I don't think they're exactly 
the same.

> With those points in mind, here is my general remedy:  each voter may
> submit two ballots, the first of which is understood to be a
> substitute for the polling information that would be used for
> strategizing in the base method if there were no DSV.   Then near
> optimal strategy (assuming the approximate validity of this 
> substitute polling information) for the base method is applied to the
> second set of ballots to produce the output ballots, which are then
> counted as in the base method.

This externalizes strategy and criterion failures to the second set of 
ballots, though, and so feels a bit like cheating. To show it more 
clearly, consider a method like this:

1. Voters submit two ballots each.
2. There's an IRV election based on the first set of ballots.
3. The pairwise winner, with respect to the second set, of the two 
candidates who IRV eliminated last, wins.

The method is monotone when you consider the second set of ballots, but 
not with respect to the second or to both.

It also seems a bit odd that a DSV method, which is supposed to 
strategize so that the voter doesn't have to, should ask the voter for 
both a sincere ballot and a strategic one.