[EM] : Chicken problem (was: SODA and the Condorcet

Sun Aug 7 08:11:19 PDT 2011

Sorry if the explanation was not clear enough. A basic tree method with bullet votes indeed has the limitation that you mentioned below (inability to influence the preference order in the competing branch).

I think the "explicit clone preprocessing of the votes + Condorcet" description that I gave below is a quite accurate definition of a method that both eliminates the clone problems and has rich ballots (rich enough to take position also on the order within the competing branch).

Building trees could be difficult in some cases. If the clones are from one party, it should not be too difficult to agree that all candidates of one party will be explicit clones. The strongest candidate (and supporters) should accept this because they are more likely to win if he is the strongest candidate of the explicit clone set. The second strongest clone could plan to use a strategy and ask his supporters not to vote for the strongest clone. But maybe saying this aloud in the meeting that discusses the benefits of declaring the candidates of this party as explicit clones would not be an option. Maybe some other explanations could be used. What would be good ones? My guess is that the interest of a party to win the election is so strong that it would be quite natural to use the explicit clone option.

If the clones are from two different parties, then the negotiations are one step more difficult. But also here this is just a proposal of cooperation. The idea is probably just to guarantee that the correct wing will win. I have seen also the weaker party of a wing to give up the idea of nominating its own candidate, just to guarantee that the correct wing will win. Having the option of explicit clones would be beneficial to them, and would allow them to nominate their own candidate. And also the stronger party would probably benefit of this agreement to support the strongest of the clones.

Tree negotiations were quite complex in the binary tree case that was supposed to solve the free riding problems. But this clone problem is less difficult. Maybe the negotiations are not that difficult. If trees are seen as a natural way to provide a structured set of candidates, then they could be very natural. If they are seen as a special defensive approach to respond to the risk of someone using the chicken strategy, then it could happen that people would fail to nominate explicit clones and someone would try that strategy (but maybe one would learn after one failure).

I keep reminding of the benefits of trees because I see them as one very basic approach to eliminating the strategy problems. Trees can be seen also as one approach to fixing the problems that Arrows pointed out (= make the candidates "non-equal") (or not really fix but escape in one quite elegant way). Sorry again if my thoughts appear to be immature and that I didn't name one explicit method as a solution to the problem (or that I misled by referring vaguely just to a tree method (that would by default use bullet votes)).

Juho

On 7.8.2011, at 17.38, Jameson Quinn wrote:

> Please, finish elaborating and describing a method before you claim benefits for it. I think that building the trees is not as easy or safe as you think. I know that I myself have been guilty at times of claiming benefits for something before I'd sat down and really worked it out on paper, and I'm sorry for it; that's exactly why I know how much of a waste of everyone else's time it can be.
> 
> JQ
> 
> 2011/8/7 Juho Laatu <juho4880 at yahoo.co.uk>
> I sent also another mail that explained that the basic / simplest tree method uses bullet votes (and is therefore limited to giving opinions that influence one branch only), and that trees can be used with richer votes too. In that case tree methods become hybrids since the tree concept and the idea of explicit clones can be combined with many different vote counting rules.
> 
> As I described in that mail, trees could be used also just as preprocessing rules that force the votes to respect the agreed clone sets. After this is done, those "clone compliant" votes could be consumed by any method (e.g. some Condocet method could take the "clone compliant" ranked votes as input).
> 
> One could thus indicate which candidate of the competing branch is preferred by voting e.g. A>B>C (where B and C are the clones of the competing branch, and A is the only candidate of one's own branch). This vote is "clone compliant".
> 
> Juho
> 
> 
> 
> On 7.8.2011, at 16.48, Jameson Quinn wrote:
> 
>> Like IRV, tree approaches would not allow supporters of candidates from other branches to help decide which of the "clones" on the winning branch wins. They would also not allow a situation where A likes B but B doesn't like A. In both cases, this leads to an IRV-like center-squeeze problem, which, especially in one-dimensional scenarios, is quite costly in terms of Bayesian Regret.
>> 
>> Perhaps you can think of ways to fix this, but if so, you'll have to be more specific than "tree methods".
>> 
>> ....
>> 
>> As to SODA; I included my proposed chicken-fix rule in the "optional rules" section of the SODA page. And it's remarkably unsatisfying. Here is a fix for what I think is the most significant practical problem scenario in all of voting theory; and yet half the people would skip that section, half of the people who read it wouldn't understand why it matters, and half the people who did wouldn't understand why it works. So, although this is something I'd love to be able to brag about more, I didn't even include "fixes the chicken problem" anywhere among the top 15 advantages in the advantages section.
>> 
>> Oh well.
>> 
>> Jameson Quinn
>> 
>> 2011/8/7 Juho Laatu <juho4880 at yahoo.co.uk>
>> On 7.8.2011, at 2.04, Jameson Quinn wrote:
>> 
>>> 
>>> 
>>> 2011/8/6 <fsimmons at pcc.edu>
>>> Jan,
>>> 
>>> IRV elects C like all of the other methods if the B faction doesn't truncate.  But IRV elects A when the B
>>> faction truncates.  Of course, with this knowledge, the B faction isn't likely to truncate, and as you say C
>>> will be elected.
>>> 
>>> The trouble with IRV is that in the other scenario when the B faction truncates sincerely because of
>>> detesting both A and C, IRV still elects A instead of B.
>>> 
>>> Also, if the A faction votes A>B, then B clearly should win, but does not under IRV. So yes, IRV solves the chicken dilemma, but in so doing causes other problems. (This same argument, as it happens, works against tree-based methods.)
>>> 
>>> I still claim that SODA is the only system I know of that can solve the chicken dilemma without over-solving it and making other problems.
>> 
>> I wouldn't say that trees "over-solve" the problem. The tree approach to the chicken problem could be called "explicit clones". That's quite natural. Some candidates just announce that they are clones and that they will support each others. That sounds like a pretty exact solution, not an over-solution.
>> 
>> Do trees "cause other problems" then? They do not allow the voter to support one of the clones without supporting the other. But this is exactly what the intention of the explicit clone approach is. Also the need to declare a branch in the tree could be considered to be a practical problem / increased complexity. And the need to identify the clones is an extra task / problem. But maybe not really. What other (more serious) problems would the trees cause?
>> 
>> Juho
>> 
>> 
>> 
>> 
>> 
>> ----
>> Election-Methods mailing list - see http://electorama.com/em for list info
>> 
>> 
>> ----
>> Election-Methods mailing list - see http://electorama.com/em for list info
> 
> 
> ----
> Election-Methods mailing list - see http://electorama.com/em for list info
> 
> 

-------------- next part --------------
An HTML attachment was scrubbed...
URL: <http://lists.electorama.com/pipermail/election-methods-electorama.com/attachments/20110807/fdad6147/attachment-0004.htm>