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your online self | 194 comments (194 topical, editorial, 0 hidden)
Re: your online self (4.00 / 2)
I may be wrong but much of the way I learned to categorise was with a tree structure, best represented by the tree of life. A man is a male member of the human species of the primate genre of the mammal branch etc... Each of these distinctions being fairly exclusive.

i.e. when dividing within a group we tend to search for the overarching difference between the different parts, with an essentialist approach ; we create "muslim" and "jew" categories, despite the fact that many muslims and many jews used to share the same culture. Black and White categories - where does the north of Africa fit ? Fruit and produce - and endless debate about the status of the tomato.

Categories and nuance don't fit well together. It seems to go back to the Platonician ideal - instances are supposed to be a representation of a theoretical  and perfect idea, which represents the truth. Thus, as we build representations, we are unable to detach the instance from its ideal, and admit that different categories often overlap.


Un roi sans divertissement est un homme plein de misères

by linca (antonin POINT lucas AROBASE gmail.com) on Tue Jan 1st, 2008 at 05:56:45 PM EST
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Re: your online self (none / 1)
Hmm, that ties in very well with some work I've done on statistical classification and clustering and the problems with the whole theory and practice of it. Specifically with dendrograms.

We have met the enemy, and he is us — Pogo
by Carrie (migeru at eurotrib dot com) on Tue Jan 1st, 2008 at 06:22:44 PM EST
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Re: your online self (none / 0)
Please elaborate. That sounds interesting.

Un roi sans divertissement est un homme plein de misères
by linca (antonin POINT lucas AROBASE gmail.com) on Tue Jan 1st, 2008 at 07:51:13 PM EST
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Re: your online self (none / 1)
Well, the tree of life actually has an underlying theory that explains why it would be that way (evolution involves speciation, that is branching only and not convergence) and a transversal cut across the tree represents a particular point in time.

With Ring Species, however, one has to be extra careful. But that is only a difficulty associated with a particular branching point.

Now consider a general classification problem. I give you a population and you have to figure out how many subpopulations there are in it and which subpopulation each individual belongs to. There are parametric models which have problems of their own, but a nonparametric way to do it is to calculate a distance function and then construct a tree out of it. There are bottom-up and top-down algorithms. You described a top-down algorithm. The main problem is that, unlike the case of the tree of life where the tree being represented actually follows evolutionary time in one direction, if you have a group breaking up into four subgroups because of two dichotomies, the order of breaking will make the tree look different and it may obscure the common characteristics between subbranches of different branches.

That is, the tree is the wrong kind of topology in some cases.

We have met the enemy, and he is us — Pogo

by Carrie (migeru at eurotrib dot com) on Wed Jan 2nd, 2008 at 08:17:32 AM EST
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Re: your online self (none / 0)
The problem being that the tree is the dominant implicit classification paradigm in the societies I know (witness the 'US is a republic, not a democracy !' as another example). That leads to trouble. (And I think I remember reading about ethnologies of societies with had very different classification paradigms, which meant they had no concept of "tree" for example...)

Un roi sans divertissement est un homme plein de misères
by linca (antonin POINT lucas AROBASE gmail.com) on Wed Jan 2nd, 2008 at 08:59:58 AM EST
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Re: your online self (none / 0)
The key issue is do you have a partition (exclusive, exhaustive classes) or don't you?

We have met the enemy, and he is us — Pogo
by Carrie (migeru at eurotrib dot com) on Wed Jan 2nd, 2008 at 11:39:57 AM EST
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Re: your online self (none / 0)
Well, it sure seems French has some problem with non-exclusive or ; ou is often an implicit XOR. I think the same holds in English.

Un roi sans divertissement est un homme plein de misères
by linca (antonin POINT lucas AROBASE gmail.com) on Wed Jan 2nd, 2008 at 01:26:07 PM EST
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your online self | 194 comments (194 topical, 0 editorial, 0 hidden)
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