[EM] Another auto districting proposal (Crystal districting?)

[Juho]

I agree that one should aim at criteria that are close to what matters  
in the lives of the people. It is more important to have districts  
that people find natural than to optimize the rules from some  
algorithm centric viewpoint (that is ok too, but should not take the  
lead). The criteria need to be computationally feasible to check but  
it is no problem whatsoever if the best identified solution is not  
proven to be the best overall (as long as it is good despite of this)  
(btw, the solutions at your page seemed to very good and natural from  
this point of view). Generic optimization algorithms are good and  
efficient enough for most purposes.

Strategies / gerrymandering is typically not a problem since the  
process is too complex to master (and it is not possible to control  
all the input parameters).

You discussed also the possibility of forming the districts so that  
they reflect the interests of the community. One simple trick would be  
to allow each atomic block to indicate which neighbouring blocks they  
consider "close" vs. "distant". Those weights could be easily included  
in the districting criteria. Maybe the voters could indicate their  
preferences in the elections, and these preferences would be taken  
into account when forming the districts for the next election. Not  
necessarily a practical idea, just one example of more complex rules  
that could be used if people find them useful.

You mentioned that the population of each district should be within  
some given limits. That may be a good approach. One could also  
determine some criterion that rewards solutions in which the districts  
are of equal size. But because the size of the atomic blocks may be so  
large that they would cause some distortion in the results it may be  
better not to start calculating the differences (and distort the  
otherwise good results) but use other criteria to determine which  
solution is the best.

(One could go also further and try to use generic optimization to  
count the actual election results too, and maybe also districting at  
one go. That could mean e.g. different districting for each party (the  
smallest party could have just one seat and one district that covers  
the whole country). Nomination of candidates to different districts/ 
blocks could be somewhat strategic (each candidate trying to beat  
other candidates of the same party).

Juho



On Nov 20, 2009, at 3:37 PM, Brian Olson wrote:

> I agree with Juho. Define what a good redistricting result is,  
> preferably in terms that produce a single valued numeric score, and  
> then produce maps by whatever means you like and let the best map win.
> I haven't seen a procedure defined that I was sure would always  
> produce good districts. While many procedures have been defined  
> where every step is fair, that doesn't entail that the result would  
> be good. There's always some side effect of the method which results  
> in odd unnaturally shaped districts.
>
> My current favorite score function for district maps is*:
> Minimize the average distance per person to the geographic center of  
> their district.
> (This is currently what I've solved for at http://bolson.org/dist/ )
>
> But this also feels tantalizingly good and might be better:
> Minimize the average distance per person to the population center of  
> their district.
>
> Unfortunately when laying down criteria like this, it's a more  
> philosophical argument rather than something that can be measured  
> and engineered.
>
> I've seen lots of proposals that are purely geometric over the land  
> encompassed by a district, but I think that is a mistake. We're not  
> redistricting land. We're redistricting spatially distributed people.
>
>
> *This doesn't include the _requirements_ which a map must first  
> pass, otherwise it is simply thrown out. 1. Contiguous districts. 2.  
> District populations must be within 0.5% of the average district  
> population.
>
> On Nov 19, 2009, at 11:00 AM, Juho wrote:
>
>> My thinking is that it might be easier to agree about the targets  
>> rather than the whole procedure. The targets can be simpler to  
>> define.
>
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