[EM] A DSV method inspired by SODA

[fsimmons at pcc.edu]

Jameson,

for my benefit could you elaborate on what you mean by hijacking strategy, especially in the context of 
amalgamation of factions.

Is ordinary Range susceptible to hijacking?  If not, then neither is amalgamation of factions per se, since 
Range scores are identical with or without amalgamation of factions.

Forest

----- Original Message -----
From: Jameson Quinn 
Date: Saturday, July 30, 2011 4:35 pm
Subject: Re: [EM] A DSV method inspired by SODA
To: fsimmons at pcc.edu
Cc: election-methods at lists.electorama.com

> 2011/7/30 
> 
> > One of the features of SODA is a step where the candidates 
> decide what
> > their approval cutoffs will be.on
> > behalf of themselves and the voters for whom they are acting 
> as proxies.
> > One of the many novel features
> > is that instead of making these decisions simultaneously, the 
> candidates> make them sequentially with
> > full knowledge of the decisions of the candidates preceding 
> them in the
> > sequence.
> >
> > I wonder if anybody has ever tried a DSV (designated strategy 
> voting)> method based on these ideas.
> >
> > Here's one way it could go:
> >
> > Voters submit range ballots.
> >
> > Factions are amalgamated via weighted averages, so that each 
> candidate ends
> > up with one faction that
> > counts according to its total weight. For large electorates, 
> these faction
> > scores will almost surely yield
> > complete rankings of the candidates.
> >
> > From this point on, only these rankings will be used. The 
> ratings were
> > only needed for the purpose of
> > amalgamating the factions. If we had started with rankings, 
> we could have
> > converted them to ratings via
> > the method of my recent post under the subject "Borda Done 
> Right." In
> > either case, once we have the
> > rankings from the amalgamated factions we proceed as follows:
> >
> > Based on these rankings the DSC (descending solid coalitions) 
> winner D is
> > found. The D faction ranking
> > determines the sequential order of play. When it is candidate 
> X's turn in
> > the order of play, X's approval
> > cutoff decision is made automatically as follows:
> >
> > For each of the possible cutoffs, the winner is determined 
> recursively (by
> > running through the rest of the
> > DSV tentatively). The cutoff that yields the best (i.e. 
> highest ranked)
> > candidate according to X's faction's
> > ranking, is the cutoff that is applied to X's faction.
> >
> > After all of the cutoffs have been applied, the approval 
> winner (based on
> > those cutoffs) is elected.
> >
> > It would be too good to be true if this method turned out to 
> be monotone.
> > For that to be true moving up
> > one position in the sequence of play could not hurt the 
> winner. Although I
> > think that this is probably
> > usually true, I don't think that it is always true. Anybody 
> know any
> > different?
> >
> 
> 
> I'm pretty certain that even if a method like this could be 
> monotone, the
> amalgamation in the first step breaks it, because of a 
> "candidate hijacking"
> strategy.
> 
> I have no opinion if some other way to do this step would give 
> monotonicity.I'd like to think so, but I wouldn't bet on it.
> 
> JQ
> 
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