[EM] SODA might be the method we've been looking for.

[Jameson Quinn]

One kind of SODA strategy which I didn't discuss is candidate
preference-declaration strategy aimed, not at directly attaining a better
result, but at attracting votes. This would basically take two forms:
established candidates truncating upstarts to try to minimize their
importance, and a candidate altering their true preference order to better
conform to some important fraction (probably the majority) of their voters.
In both cases, these phenomena would tend to have a "bandwagon effect"
which is arguably socially beneficial - minimizing the chances that a weak
Condorcet winner will win the election, while strengthening the margin of
true Condorcet winners. So I'm not worried about this sort of strategy
being a problem.

Jameson

2011/12/15 Jameson Quinn <jameson.quinn at gmail.com>

>
>
> 2011/12/15 Andrew Myers <andru at cs.cornell.edu>
>
>> On 7/22/64 2:59 PM, Andy Jennings wrote:
>>
>>> I don't see any huge theoretical downsides.  Do others still have
>>> reservations about SODA?  I realize that some people may be opposed to
>>> delegation, in principle.  And others think delegable systems just don't
>>> have a chance of getting implemented.  So I think these debates about which
>>> is the best voting system in the standard (non-delegable) model are still
>>> useful.  I also think it's useful for Jameson to inject a plug about SODA
>>> every now and then.
>>>
>> I will repeat what I've written before:
>>
>> > I have to agree. SODA to me seems quite complex. It appears to pose
>> difficult strategic decisions for candidates and even for voters.
>>
>> Thanks for the honest response.
>
> What do you think would help alleviate this largely-false appearance?
> Voter strategy is limited to a few cases:
>
> 1. Correct approval strategy in case your favorite candidate's preferences
> differ significantly from yours. People on this list understand approval
> strategy; in my opinion, it's not ideal, but it's no worse than plurality
> strategy, which most people tolerate. And I estimate that perhaps a third
> or fewer voters will differ significantly from their favorite candidates.
> If "significantly" only counts differences in the order between the two
> frontrunner candidates, that kind of number makes sense.
>
> 2. Attempts at "chicken" strategy in a few cases. In the classic A+B vs C
> case, such strategy can only work if C has no preference between A and B.
> (Under one rule variant of SODA, even an honest preference that wasn't
> predeclared would be sufficient to avoid a chicken dilemma). Note that,
> unlike in approval/Range/MJ, the only way a chicken strategy can work for A
> is by making it impossible for B to win the election; chicken strategy is
> *always* either ineffective or dangerous. So it seems to me that in SODA,
> unlike those systems, there is no slippery slope to a chicken dilemma.
>
> As for candidate strategy, that comes in two flavors:
>
> 1. Preference declaration strategies. Again, these mainly come down to
> chicken strategies, and there are several restraints even on such
> strategies. If A truncates B, B can retaliate; this should keep it from
> happening unless A is clearly a second-string candidate, in which case it
> may be a good thing. Also, C could intervene to avoid the dilemma.
>
> 2. Post-election strategy. This is a sequential, perfect-information game;
> there's a single optimal strategy, and in any real election it's pretty
> easy to calculate. (I can imagine artificially-balanced situations with
> dozens or hundreds of candidates which might be NP-hard; but in real life,
> it basically comes down to finding the delegated CW).
>
> Also note that journalists would quickly work out and publish the optimal
> strategy and all plausible variations thereof, so the candidates would not
> have to work it out on their own.
>
> So, I can't quite give a blanket denial that strategy matters, but I can
> give a qualified one: in real life SODA elections, it is not worth worrying
> about strategy. Having read the above, can you see any way I could say that
> better? I want to be able to allay this concern; strategy issues are an
> outstanding strength of SODA, not a weakness.
>
> Jameson
>
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