# [EM] A DSV method inspired by SODA

fsimmons at pcc.edu fsimmons at pcc.edu
Thu Aug 4 14:01:17 PDT 2011

```Of course DSC and DAC are the same when rankings are complete.  I was only going to use it to determine the first player, and with amalgamated factions (almost surely) the rankings would be complete.

Of course there are many variations of this DSV idea [e.g. we could use chiastic approval to pick the first player], but the main contribution of SODA is the idea of sequential determination of the approval cutoffs.  That eliminates the need for mixed (i.e. probabilistic) strategies.  In other words, it makes the DSV method deterministic instead of stochastic.  I think a deterministic DSV method is easier to sell than a stochastic one, even though personally I would be happy with "strategy A" applied to the ballots one by one in some random order.  In other words, the approval cutoff on the current ballot is next to the current approval winner on the side of the approval runnerup.  If there is no CW, then the winner depends on the random order of the ballot processing.  The public might have a hard time with that fact.

----- Original Message -----
From: Jameson Quinn
Date: Thursday, August 4, 2011 7:41 am
Subject: Re: [EM] A DSV method inspired by SODA
To: fsimmons at pcc.edu
Cc: election-methods at lists.electorama.com

> I suspect that SODA would be Condorcet compliant (over ballots)
> if the first
> player was, not the DSC winner, but the DAC winner (re-ordering
> between each
> delegated assignment).
>
> I'll see if I can work up a proof on this.
>
> JQ
>
> 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?
> > ----
> > 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/20110804/745d2816/attachment-0004.htm>
```