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

[Jameson Quinn]

The "DSV fix" doesn't just have philosophical problems. It has practical
ones. For the first ballots, you are essentially begging the voters to
strategize, to the point where the supposedly-optimal DSV algorithm in the
second ballot becomes a hopeless patsy. In particular, I suspect that (with
"rational" voters), burial would be so common in the first ballot that DH3
would be common. Then, in an election between A,B,C, and Hitler, whichever
one of A, B, or C was most likely to rank above Hitler among the tiny
fraction of voters who honestly find Hitler palatable, would win. That is a
horrible result.

Let me propose, as a straw man, another system - "Sicilian DSV". You submit
1 range ballot, and a non-negative integer, your "recursive strategy level".
>From this, the system calculates two ballots - "strategic" and honest - for
a "fixed DSV". If your recursive strategy level is 0, these two ballots are
the same. Otherwise, for RSL n, the strategic ballot is calculated as
optimal if all other voters choose RSL n-1.

Never vote against a Sicilian, when death is on the line!

BUT - after the election, the RSL distribution for each candidate's voters
would be published. Presumably, parties which used non-zero RSLs to win,
would lose support in later elections, because people prefer honesty.

Obviously, this system involves absurd algorithms and a lot of computation.
(It might actually be low-order polynomial; I don't know. But if so, it
would have a high constant factor.)

Food for thought....
JQ

2010/11/23 Kristofer Munsterhjelm <km-elmet at broadpark.no>

> 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.
>
> ----
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>
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