[EM] Challenge2 - give an example where MFBC is violated for Condorcet methods

[Peter Zbornik]

Juho,

I think the coming paper in votingmatters on hybrid methods, shows
that strategy voting can be a problem in Condorcet methods (beatpath).

I would say that "fears" in a sense always are irrational, as they are
emotions. I think, that fears  increase the chance of survival in many
cases though :o)

If there is no apparent "Pol Pot" among the candidates (i.e. the
extremist, which I would rather see not elecred than having my
candidate elected), and especially if someone has managed to dumb the
voters to vote sincerely, then bullet voting is an excellent strategy
to increase the chances of having your most preferred candidate
elected as you bury all your competitors. LNH will not decrease the
chance of my candidate winning and FBC neither, as all the other
candidates are equally ranked below the null candidate ("none of the
above"). I would say, that bullet woting increases the weight of my
vote compared to a sincere vote, i.e. the bullet voter gets a
competitive advantage.

It would be nice to see a study on this topic.

I would say that bulletvoting is a rational strategy, if you have
limited information on how others are going to vote, but know they
will vote sincerely and if you want to get your candidate eleced.

If the bulletvoting strategy is to be called irrational, then it might
be good to show the irrationality of the strategy. Otherwise, the
claim that a strategy is irrational might be irrational itself.
Alternatively, labelling a strategy irrational might be a rational
strategy to increase the prevalence of certain  strategies like
sincere voting that might be less efficient in electing the preferred
candidate than the strategy labeled irrational.

I think, that by creating an ethical rule, which says, "be honest" and
by labelling other rules "irrational", those bold enough to ignore the
rule might be given an advantage in the elections.

Best regards
Peter Zbornik

On 6/8/11, Juho Laatu <juho4880 at yahoo.co.uk> wrote:
> On 7.6.2011, at 10.53, Peter Zbornik wrote:
>
>> I'd say that FBC (and LNH) is quite a big problem for Condorcet
>> methods, at least for someone (like me) who think sincere voting
>> should be the norm.
>
> One could also claim that in typical political elections Condorcet methods
> will work fine, and people need not worry about the fact that these methods
> fail FBC and LNH. FBC does not mean that there would be a clear need to
> consider "betraying" one's favourite candidate, and LNH does not mean that
> there would be a clear need to consider truncating one's vote in order not
> to harm oneself. A much better advice to the voters is to vote sincerely.
> (And I note again that I have not seen good general advices on how people
> could in practice exploit the theoretical vulnerabilities of Condorcet
> methods in real elections.)
>
>> It seems that there is a risk, that Condorcet methods are reduced to
>> plurality-like methods due to voting strategies that exploit the fact
>> that FBC and LNH do not hold.
>
> That could happen in principle, but I believe in most environments that
> would not be the case. And even if that would happen, probably those fears
> (leading to bullet voting or plurality-like methods) would be irrational.
>
> Juho
>
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>
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>
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