[EM] Manipulability stats for (some) poll methods

[Kristofer Munsterhjelm]

On 2024-04-27 14:44, Chris Benham wrote:
> Kristofer,
> 
>>
>> The simulator uses full ballots, so Smith//DAC is the same as 
>> Smith//DSC. If truncation would make the method more resistant, that's 
>> not reflected here. 
> 
> As the nominator of Smith//DAC I strongly request that in that case you 
> list it as Smith//DSC  and accept that the Smith//DAC poll candidate 
> hasn't been simulated. It has a  strong truncation incentive, and 
> forcing full strict ranking destroys most of its point.

My thought for adding it was like this:

Suppose that the honest voters have opinions about every candidate. 
Then, if they're being honest, they could rank them all. If the honest 
voters have to do defensive strategy to protect themselves in such a 
case, that's a limitation of the method.

On the other hand, if the truncation incentive is an offensive strategy 
that can be used once the honest ballots are submitted, then truncation 
strategy will only increase the method's manipulability.

So the manipulability should still give a lower bound on its 
manipulability in the case that honest voters just rank everybody.

That said, I could try to implement a quick and dirty truncation setup, 
something like truncating a random number of ranks down, or truncating 
at mean utility. Would that solve the problem, in your opinion?

> Also with the voters fully strict ranking, the three versions of Raynaud 
> become the same thing and those three "winning votes" Condorcet methods 
> become the same thing as Margins.

I know. I'm using the names of the methods as indicated in the poll to 
make it clear which ones I'm referring to, even though some of their 
description is redundant.

-km