Re: [EM] A distance based method

2011-07-13 Thread Jameson Quinn
2011/7/14 Kristofer Munsterhjelm > Jameson Quinn wrote: > >> I doubt it's monotonic, though it's probably not a practical problem. That >> is, it would probably be totally impractical to try to use the >> nonmonotonicity for anything strategic, and it wouldn't even lead to Yee >> diagram ugliness

Re: [EM] A distance based method

2011-07-13 Thread Kristofer Munsterhjelm
Jameson Quinn wrote: I doubt it's monotonic, though it's probably not a practical problem. That is, it would probably be totally impractical to try to use the nonmonotonicity for anything strategic, and it wouldn't even lead to Yee diagram ugliness. Nonmonotonicity could be considered an erro

Re: [EM] Yee diagrams and Condorcet

2011-07-13 Thread Kristofer Munsterhjelm
fsimm...@pcc.edu wrote: If we abandon the Euclidean metric, then we also abandon Voronoi Polygons; the corresponding idea for more general metrics is that of a Dirichlet region. That's strange. The Wikipedia article on Voronoi diagrams mention diagrams based on L_1 and Mahalanobis distance. Is

Re: [EM] A distance based method

2011-07-13 Thread Kristofer Munsterhjelm
fsimm...@pcc.edu wrote: Here's a simpler version that is basically the same: Make use of cardinal ratings so that the rating of candidate X on ballot b is given by b(X). Define the closeness of candidate X to candidate Y as the dot product Sum b(X)*b(Y) where the sum is taken over all b in t

Re: [EM] A distance based method

2011-07-13 Thread Jameson Quinn
I doubt it's monotonic, though it's probably not a practical problem. That is, it would probably be totally impractical to try to use the nonmonotonicity for anything strategic, and it wouldn't even lead to Yee diagram ugliness. 2011/7/13 > Here's a simpler version that is basically the same: >

Re: [EM] Yee diagrams and Condorcet

2011-07-13 Thread fsimmons
Here's how to prove it with a non-euclidean metric. 1. Assume that we are dealing with a metric (like all of the L_p metrics) whose "balls" are symmetric with respect to the origin. 2. Suppose that AB and DE are line segments with the same midpoint C, and define the set pi={x| d(x,A)=s(x,B)}

Re: [EM] Yee diagrams and Condorcet

2011-07-13 Thread fsimmons
If we abandon the Euclidean metric, then we also abandon Voronoi Polygons; the corresponding idea for more general metrics is that of a Dirichlet region. It would be amusing to see Yee diagrams based on L_1 and L_infinity metrics Of course, Yee uses the L_2 metric to make his pictures rotation

Re: [EM] A distance based method

2011-07-13 Thread fsimmons
Here's a simpler version that is basically the same: Make use of cardinal ratings so that the rating of candidate X on ballot b is given by b(X). Define the closeness of candidate X to candidate Y as the dot product Sum b(X)*b(Y) where the sum is taken over all b in the set beta of ballots.

Re: [EM] Yee diagrams and Condorcet

2011-07-13 Thread Jameson Quinn
That proof assumes a euclidean distance metric. With a non-Euclidean one, the "planes" could have kinks in them. I believe I have heard that the result still holds with, for instance, a city-block metric, but I cannot intuitively demonstrate it to myself by imagining volumes and planes as in this p

Re: [EM] Centrist vs. non-Centrists (was A distance based method)

2011-07-13 Thread Jameson Quinn
2011/7/13 > > > - Original Message - > From: Kristofer Munsterhjelm > > fsimm...@pcc.edu wrote: > ... > > There may also be another scenario where Majority Judgement (or > > median > > ratings, for that matter) would do better than ranked methods. > > If it's > > possible for the voters t

Re: [EM] Yee diagrams and Condorcet

2011-07-13 Thread fsimmons
Actually, any centrally symmetric distribution will do, no matter how many dimensions. The property that we need about central symmetry is this: any plane (or hyper-plane in higher dimensions) that contains the center of symmetry C will have equal numbers of voters on each side of the plane..

Re: [EM] Centrist vs. non-Centrists (was A distance based method)

2011-07-13 Thread fsimmons
- Original Message - From: Kristofer Munsterhjelm > fsimm...@pcc.edu wrote: ... > There may also be another scenario where Majority Judgement (or > median > ratings, for that matter) would do better than ranked methods. > If it's > possible for the voters to agree on what, say, "Good

Re: [EM] Yee diagrams and Condorcet (was Centrist vs. non-Centrists (was A distance based method))

2011-07-13 Thread Bob Richard
After looking up some old email threads, it now seems to me that I made a significant mistake in the post below. It is true that the model underlying Yee diagrams guarantees that there will always be a Condorcet winner. But apparently that has nothing to do with the two dimensions being orthogo

Re: [EM] A distance based method

2011-07-13 Thread Kristofer Munsterhjelm
fsimm...@pcc.edu wrote: Trying to build a metric from a set of ranked ballots is fraught with difficulties, and your outline of a procedure for doing it is interesting to me. The simplest, least sophisticated idea I have so far that seems to have some use is to define the distance between two ca

Re: [EM] Centrist vs. non-Centrists (was A distance based method)

2011-07-13 Thread Jameson Quinn
2011/7/13 Kristofer Munsterhjelm > fsimm...@pcc.edu wrote: > > Of course if we have a multiwinner method, we don't want all of the >> winners concentrated in the center of the population. That's why we >> have Proportional Repsentation. >> >> Also the purpose of stochastic single winner methods

Re: [EM] Yee diagrams and Condorcet (was Centrist vs. non-Centrists (was A distance based method))

2011-07-13 Thread Kristofer Munsterhjelm
Bob Richard wrote: On 7/13/2011 11:14 AM, fsimm...@pcc.edu wrote: Jameson, I'm surprised that you consider a Condorcet method to be too extremist or apt to suffer center squeeze. Think Yee diagrams; all Condorcet methods yield identical diagrams, while center squeeze shows up clearly in met

Re: [EM] Centrist vs. non-Centrists (was A distance based method)

2011-07-13 Thread Kristofer Munsterhjelm
fsimm...@pcc.edu wrote: Of course if we have a multiwinner method, we don't want all of the winners concentrated in the center of the population. That's why we have Proportional Repsentation. Also the purpose of stochastic single winner methods ("lotteries") is to spread the probability around

Re: [EM] Centrist vs. non-Centrists (was A distance based method)

2011-07-13 Thread Jameson Quinn
2011/7/13 > Jameson, I'm surprised that you consider a Condorcet method to be too > extremist or apt to suffer center > squeeze. > Hmm... you're right, I hadn't recognized that your "remove one of closest pair" method was Condorcet-compliant, as any pairwise method. > > Think Yee diagrams; all

[EM] Yee diagrams and Condorcet (was Centrist vs. non-Centrists (was A distance based method))

2011-07-13 Thread Bob Richard
On 7/13/2011 11:14 AM, fsimm...@pcc.edu wrote: Jameson, I'm surprised that you consider a Condorcet method to be too extremist or apt to suffer center squeeze. Think Yee diagrams; all Condorcet methods yield identical diagrams, while center squeeze shows up clearly in methods that allow it.

[EM] Centrist vs. non-Centrists (was A distance based method)

2011-07-13 Thread fsimmons
Jameson, I'm surprised that you consider a Condorcet method to be too extremist or apt to suffer center squeeze. Think Yee diagrams; all Condorcet methods yield identical diagrams, while center squeeze shows up clearly in methods that allow it. Of course if we have a multiwinner method, we do