[EM] Write-ins break condorcet summability

[Dave Ketchum]

I believe I have the answer for Condorcet, and that you should be able to 
build on this for ratings.  I also think of voting at multiple precincts, 
doing an array at each precinct, and summing the arrays for total district.

May have to scan each ballot for new names at start of its processing, so 
that new names are added only between ballots.  Certainly do not have to 
scan all the ballots for new names before starting to count.

Besides the array for all current candidates, keep a dummy column for a 
dummy candidate, who always loses to every voted candidate.

When a new candidate turns up, start its new array column and row with a 
copy of the dummy column and a row of zeros, for this candidate has won 
nothing to date.

On Sat, 9 Jul 2005 19:44:25 -0700 (PDT) bql at bolson.org wrote:

> How do you compare a new entry all the ones that came before? Having a 
> policy for incomplete ballots isn't good enough because it doesn't 
> compare a new name to the other names on ballots before the first ballot 
> to include a new write-in candidate. So, there must always be a first 
> pass through all the ballots to collect all the names.
> 
> There is an out depending on the partial ballot policy. I'm trying to 
> write a ratings based implementation with signed ratings. Since voters 
> can express positive or negative I think it's fair to assign zero to 
> unvoted choices. This breaks summability because on encountering a new 
> name you can't go back and compare to ratings. If however an unrated 
> choice is assumed to be lower than all the rest, it's possible to record 
> a new name as having lost to every other choice on as many ballots as 
> there have been.
> 
> But I think the 'no-vote is negative-infitiy' policy pretty poorly 
> represents what voters want.
> 
> If anyone can poke a hole in this and suggest a one-pass summable 
> condorcet with write-ins algorithm I'd love to hear it.
> 
> Practically in the system I'm writing making it collect write-in names 
> before counting votes won't be a problem.
> 
> Also, I'll note that Approval is still summable with write-ins.
> 
> Brian Olson
> http://bolson.org/
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  Dave Ketchum   108 Halstead Ave, Owego, NY  13827-1708   607-687-5026
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