Talk:Complex system/Archive 2

...tighten this thing up, not make it more vague

I added systems theory and some other stuff to the "see also" section. I removed the link to "neurolinguistic prgramming" in that section. I looked at the article, and while I could see a certain tangential relevence (I suppose), it was so tangential that the inclusion of NLP in the see also section would suggest the inclusion of thousands of other articles with similarly tangential relationships to complex systems. We are trying to tighten this thing up, not make it more vague Duracell 18:26, 28 November 2005 (UTC)

Making a clear distinction between Complex system and Complex Adaptive System (among others) is probably needed. The 'May produce emergent phenomena' needs to link to dissipative structures. -GarOgar-

Coarse errors

I agree that the article should be rewritten, in the meanwhile I will try to fix some hideous errors like "the course of this action can be predicted in chaos theory". Actually the impredictability of chaotic systems is the heart of the matter!. All the paragraph of Complexity and Chaos theory is complete nonsense.

Just a comment on the above paragraph: the question is not wll posed, there is no point in distinguishing chaos theory from complex systems just because they are not comparable. Complex systems show normally one or more aspects of chaos or its variants (weak chaos) but Chaos theory by itself does not have any relation with Complex systems. In other words: Complex theory needs the theory of chaos but the other way is not true. Pedron 17:40, 1 May 2007 (UTC)

chaos theory

Can someone write a few sentences distinguishing complex systems from chaos theory please?

Is that enough? ;)

I am doing a PhD on the topic, would love to contribute more if people are interested to comment. -GarOgar-

hi just stumbled in on these pages. what a bold project. yes that section of the wiki is a mess. strictly speaking as described on the chaos theory wiki, chaos theory is a fairly well defined body of MATHEMATICS. The three criteria given are well defined for mathematical systems. It also is used to refer to PHYSICAL systems that seem to exhibit similar behaviors as the mathematical ones do. a distinction should be made.

as described on the complex systems wiki hmmm... we've got mathematical, cellular automata, and physical systems all mixed in. some MIGHT exhibit chaotic behavior some might not. they are, well... more COMPLEX than the simpler mathematical systems that can already exhibit chaos. hmm... defined differently though. also note that there are descrete complex systems made of finite number of parts that cannot strictly exhibit chaos as that's a property of dynamical systems on the REAL numbers. for all practical purposes though they might be FAIRLY chaotic.

i say you've got two overlapping classes of systems, complex systems being the broader and more ill defined. it's important to distinguish between mathematics, physics, engineering and philosophy on these pages...

more comments here put on Wikipedia talk:WikiProject Systems - Wikiskimmer 06:22, 29 June 2007 (UTC)

You may find David Orrell's material interesting [1]. It focuses on the unpredictability of complex systems, but still is overall about complexity and chaos theory. --Childhood's End 14:58, 29 June 2007 (UTC)

More thoughts on this here:

http://en.wikipedia.org/wiki/Talk:Chaos_theory

my last comment. at some point maybe we can write some of this into the wikis - Wikiskimmer 19:44, 29 June 2007 (UTC)

ok, so just what are complex systems?

trying to find the definition of complex system...

in the intro the article states:

However, all complex systems are held to have behavioural and structural features in common, which at least to some degree unites them as phenomena. They are also united theoretically, because all these systems may, in principle, be modelled with varying degrees of success by a certain kind of mathematics. It is therefore possible to state clearly what it is that these systems are supposed to have in common with each other, in relatively formal terms.

so what are the behavioral and stuctural features in common with all complex systems? just what is the certain kind of mathematics that modells these systems?

section complexity and modeling

his distinction between the human capacity to predict the behaviour of simple systems and its capacity to predict the behaviour of complex systems through modeling...could not be modeled after the sciences that deal with essentially simple phenomena like physics [5]. Hayek would notably explain that complex phenomena, through modeling, can only allow pattern predictions, compared with the precise predictions that can be made out of non-complex phenomena

This says that simple systems can be predicted by human capacity (?) and that complex systems can be predicted by modeling. what modeling? what's the defining feature? not the modeling that deals with simple phenomena like physics. whoah, there are plenty of complex systems studied by physicists: convection, turbulence, lasers, or are these not complex systems? see, i can't find the definitions yet! be more precise, which sorts of physical systems are too simple?

What is a pattern prediction as opposed to a precise prediction?

Examples, please!

section: complexity and chaos theory

Complexity is non-deterministic,

(A)

When one analyses complex systems, sensitivity to initial conditions, for example, is not an issue as important as within the chaos theory in which it prevails. As stated by Colander [11], the study of complexity is the opposite of the study of chaos. Complexity is about how a huge number of extremely complicated and dynamic set of relationships can generate some simple behavioural patterns

Chaotic systems don’t rely on their history as complex ones do.

Chaotic behaviour pushes a system in equilibrium into chaotic order, which means in other words, out of order. On the other hand, complex systems evolve far from equilibrium at the edge of chaos. They evolve at a critical state built up by a history of irreversible and unexpected events.

this last statement doesn't make any sense to me.

section: features of complex systems in nature. this is the ONLY feature the article says all complex systems exhibits:

(B)

Relationships are non-linear: In practical terms, this means a small perturbation may cause a large effect (see butterfly effect), a proportional effect, or even no effect at all. In linear systems, effect is always directly proportional to cause. See nonlinearity.

oops, this contradicts the statement (A)!

Wait! no discussion of abstract complex systems? i.e. mathematical ones? are there mathematical complex systems or only physical ones?

so, lets see what we've got: a complex system is a system with memory, with sensitive dependance on initial conditions or NOT with sensitive dependance to initial conditions (can't tell), is non deterministic, that produces simple behavior patterns and can be predicted by pattern models (whatever theyare) more complex than the ones used in simple physics.

That's not so great.

now there are 6 other optional features mentioned in the features section. perhaps some of these are parts of the definition? if so they should be stated as non optional.

i don't see it yet. so my suggestion still stands. have separate wikis for 60 different physical and mathematical systems and then a general article which lists them saying: some of these systems have some things in common. There are notions of nonlinearity, complexity, sensitive dependance on initial conditions, far from thermodynamic equilibrium, chaos, algorithmic complexity, etc.. that describe some of these commonalities. A general theory is far in the future.Wikiskimmer 09:09, 10 July 2007 (UTC)

Not a well defined concept yet

What are you trying to say here? - Mdd 15:07, 11 July 2007 (UTC)

i'm saying i don't see a well defined concept yet. hence why should there be a separate entry for it.

so far the article does not define what a complex system is. Instead of coming in and rewriting it (not sure if i got the organizational skills to do it) i thought i would share some thoughts first.Wikiskimmer 17:39, 11 July 2007 (UTC)

Thanks for getting to the point. You don't see a well defined concept? I agree that this point can improve. But first I have to say, that one week ago this article had a section, Definition, see [2].

Now I think that the introduction of this article can be improved. Some more quotes or referances from experts would be nice.

However I also think that the problems here are related to articles close to this subject like Complexity, Complexity theory, Complexity theory and organizations, Complex adaptive system, Complex system. A better organization would be nice - Mdd 23:51, 12 July 2007 (UTC)

yes, a freaking nest of hornets. now what? There are probably a dozen different concepts from a dozen different fields all parading under the banner of "complexity". I still think, one page which is a list of the dozens of well defined concepts that have been associated with this term and a separate very specific page for each of those concepts. for instance the page on chaotic dynamical systems chaos theory is very well defined. anyway this would require a very encyclopedaic person, or i guess we just keep pitching in. so pick one of these terms to be the page with the list, and then start writing little articles for each item on that list. I have Waldrop with me. i think i recall making a list of all the systems described in it a long time ago. 150 of them? i suppose i could whittle that down.

I will wait a bit to see if anyone else comments, and then if i'm feeling ambitious, maybe i'll start editing away. I'd like to wait for some people to defend some of the sentences i've questioned in the three articles i commented on because frankly, i don't understand half of it.

A) i don't have a grasp of the field?

B) these sentences are a mess. my feeling would be to remove them.

we shall see.Wikiskimmer 06:21, 13 July 2007 (UTC)

Renaming this article to Study of complex systems or Complex systems theory

I like to renaming this article to:

1. Study of complex systems or to
2. Complex systems theory at the moment a redirect to complex systems

The reasons for renaming are:

1. To get a better organization in the articles Complexity, Complexity theory, Complexity theory and organizations, Complex adaptive system and this Complex system.
2. This article should also be more focused on theory ans less on complexity

Renaming seems like a good first step to a better organization. - Mdd 23:36, 20 July 2007 (UTC)