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Re: Some pretty good alternate definitions of complexity



These are all reasonably good beginnings in that they don't do what most "complexity" theories I've seen are doing: these don't try to use the "old rules" to explain complexity. That's the aspect that is Rosennean about these alternate definitions. That doesn't mean they're sufficient; far from it.
 
The problem with all of these alternate "definitions" is that none of them explain why complexity has been shut out of the scientific mainstream, and therefore they don't show how the old rules (meaning reductionism and mechanism) make an organization-based paradigm a radical change of perspective from the current particle-based one. In fact, none of these definitions puts a finger on the fact that complexity forces a change of paradigm; because none of them follows the logic of what they are saying to find out what it's leading to.
 
Why is it that, historically, organization has never been considered an important feature in any given system for scientific analysis? Science never allowed organization to be defined as a basis for causal ramification in generating the behaviors and qualities of any given system. All of the alternate definitions of complexity that I found on the net and posted here refer to the causal impact of organization and yet do not follow the implications of what they are saying. The reason complexity falls outside the mainstream is precisely because the reductionist, particle-based paradigm cannot see complexity.
 
The reason my father's work was so controversial was because he DID follow those lines of logic and he saw the implications. He described the implications and wrote about them. He discussed what the ramifications were. The implications blow the reductionist particle-based paradigm right out of the water. Therefore, any definition of complexity that tries to use the old paradigm to explain complexity itself is not worth anybody's time; those people are fooling themselves. They are talking about "complicatedness".
 
In contrast, Gallagher, Appenzeller, Auyang, and Reitsma.... all seem to be on the right track but they haven't realized what the implications are. That's what I mean when I said they are all reinventing the wheel, meaning that my father's work already did that. That's why I'm looking for contact info on all of them. I figure, either they will be interested in it or they won't. But it could help them skip the hard work of reinventing science from the paradigm up, like my father was forced to do.
 
Judith
----- Original Message -----
From: Tim Gwinn
To: ***
Sent: Sunday, August 01, 2004 11:53 PM
Subject: Re: [ROSEN] Some pretty good alternate definitions of complexity

Judith,
 
Why do you consider these reasonably good definitions? I am surprised that you would consider Auyang's to be so. To me, neither the (syntactic) information measure nor the computational measure address anything to do with Rosennean complexity.
 
Regards,
Tim
 
-----Original Message-----
From: ROSEN Forum [mailto:***On Behalf Of Judith Rosen
Sent: Sunday, August 01, 2004 7:06 PM
To: ***
Subject: Some pretty good alternate definitions of complexity

I did find some reasonably good definitions on the net while I was being outraged over the Mikulecky mischaracterization of my father's definition/s:
 
Richard Gallagher and Tim Appenzeller have written several things together, most of which I can't access because one needs to be a subscriber of Science magazine apparently... But I found the following, by them:
 
?Complex System?: one whose properties are not fully explained by an understanding of its component parts.
 
and
 
at  http://www.usyd.edu.au/su/hps/newevents/Auyang1.html I found Sunny Y. Auyang's work, from which I excerpted:

4. Formal Definitions of Complexity and the Combinatorial Explosion

There is no precise definition of complexity and degree of complexity in the natural sciences. I use "complex" and "complexity" intuitively to describe self-organized systems that have many components and many characteristic aspects, exhibit many structures in various scales, undergo many processes in various rates, and have the capabilities to change abruptly and adapt to external environments. Nevertheless, there are two definitions of complexity in the information and computation sciences that can help us to appreciate nonreductive strategy for studying complex systems.

The idea of complexity can be quantified in terms of information, understood as the specification of one case among a set of possibilities. The basic unit of information is the bit. One bit of information specifies the choice between two equally probable alternatives, for instance whether a pixel is black or white. Now consider binary sequences in which each digit has only two possibilities, 0 or 1. A sequence with n digits carries n bits of information. The information-content complexity of a specific sequence is measured in terms of the length in bits of the smallest program capable of specifying it completely to a computer. If the program can say of a n-digit sequence, "1, n times" or "0011, n/4 times," then the bits it requires are much less than n if n is large. Such sequences with regular patterns have low complexity, for their information contents can be compressed into the short programs that specify them. Maximum complexity occurs in sequences that are random or without patterns whatsoever. To specify a random sequence, the computer program must repeat the sequence, so that it requires the same amount of information as the sequence itself carries. The impossibility to squeeze the information content of a sequence into a more compact form manifests the sequence's high complexity.

The information content complexity belongs to the definite description of a specific system, thus it is not useful in science because science is usually not so much interested in specific systems than in classes of system that satisfy certain general criteria. It often happens that totally random systems, which have highest information content complexity, exhibit other types of regularity than can be characterized rather simply if we are willing to adopt some other criteria of classification, e.g., use the law of large numbers. We have the probability calculus for such systems, and usually systems susceptible to the calculus are regarded as not that complex. Here we have the first instance of the theme of this talk; the flexibility to choose different criteria is paramount in scientific research.

The second definition of complexity describes not systems but problems. Suppose we have formulated a problem in a way that can be solved by algorithms or step-by-step procedures executable by computers, and now want to find the most efficient algorithm to solve it. We classify problems according to their "size"; if a problem has n parameters, then the size of the problem is proportional to n. We classify algorithms according to their computation time which, given a computer, translates into the number of steps an algorithm requires to find the worse-case solution to a problem with a particular size. The computation-time complexity of a problem is expressed by how the computation time of its most efficient algorithm varies with its size. Two rough degrees of complexity are distinguished: tractable and intractable. A problem is tractable if it has polynomial-time algorithms, whose computation times vary as the problem size raised to some power, for instance n2 for a size-n problem. It is intractable if it has only exponential- time algorithms, whose computation times vary exponentially with the problem size, for instance 2n. Exponential-time problems are deemed intractable because for sizable n, the amount of computation time they require exceeds any practical limit.

And then, of course, there's Femke Reitsma, the writer of the masters thesis which had the offending mis-characterizations of my father's work. Aside from the fact that Femke didn't do the proper homework-- by going to original sources for quotes rather than relying on second-hand interpretation-- I thought the musings on complexity contained in what I read were going in the right direction. By "right", naturally I mean the same direction that my father had already gone in! (I'm sure that comes as no surprise to anybody?) The definition of a complex system here was "a whole that cannot be fully delineated through an analysis of its component parts".

It is encouraging to see so many unrelated voices saying that reductionism cannot help us understand complexity, but each of these voices is talking about a mere piece of the larger framework that my father already developed. It's a shame to have so many people re-inventing the wheel when their time could be better spent using it to travel where my father never got to.

Judith