Talk:Complex system/Archive 1

message: it was very leaky and i think it's better now.  what say you all? --DhruvBansal
:The revision you made seems like a definite improvement to me. -R. S. Shaw 21:01, 17 September 2006 (UTC)
thread_title: i shored up the definition

message: The following paragraph was moved here because it seems to be very much POV:
We often hear of groups having "strong" or "weak" boundaries but without any clear sense of the meaning. I believe that it is possible to gain some clarity by considering connectivity. I hypothesise that an individual agent can only have a certain number of connections to other agents (with human agents this number will change according to the state of the individual and also the state of the environment). We can then think of the strength of a group's boundaries as the proportion of connections which are made within the group - the greater the proportion, the stronger the group boundaries. If all connections are made within the group it forms a closed system.
At the least, phrases containing I should be avoided. -- Kimiko 18:14, 24 Aug 2003 (UTC)
thread_title: A paragraph was moved here

message: The universe seems to be arranged in hierarchies. There are various levels at which you can understand it. The level we are most familiar with is the level of everyday life. Going down we run into the levels of organs, cells, molecular biology, chemistry. Each level has its own laws which work in certain "special cases" with all violations at the "extremes". Complex Adaptive Swarms exhibit similar layered behavior also, at each layer the swarm is made of smaller complex adaptive systems. This layered behavior doesn't appear in swarms made of simple systems. This all seems to imply that either there is no bottom to the layers of the universe(and no TOE) or, the bottom layer is made of smart, adaptive particles.--SurrealWarrior 18:09, 12 July 2005 (UTC)
thread_title: Interesting

message: There seems to be a completely lack a rigorous mathematical definition of what complex systems are, but then I suspect that is part of the problem with complex systems in that is can be tricky pinning down *exactly* what it is. Mathmo 08:34, 14 August 2005 (UTC)
thread_title: Rigorous definition??

message: As the editors above note, this article was in a rather bad state. "Complexity" is a buzzword at the moment, and unfortunately many are confused over what is entailed. As a PhD student in complex systems, I thought I'd straighten it out as best I could - including a reasonably formal (but with links to the articles you would need to make it genuinely formal) definition that I find satisfying. The emphasis in what I have written is very much on non-linearity, because that is what it is all about really.
I would really very much prefer discussion on this page rather than a petulant reversion of my edits - I spent a good hour going through this. Duracell 21:03, 13 September 2005 (UTC)
thread_title: I have re-written this

message: I just removed a sentence "complex systems are heavily inertial" inertia is a physical property of objects with mass. It is inappropriate to use in terms of a complex system, whether mathematical or real. In any case, the sentence is not true. Many complex systems are marked by rapid changes because although there are a large number of connections, there is also high connectivity, e.g. in the brain any neuron is only a hop skip and jump away from any other. So this sentence is rubbish.
The paragraph on network topology was removed.  It had some issues and may have been misplaced, but it has some useful content.  I put it back for now...  Jmeppley 17:17, 18 October 2005 (UTC)
thread_title: removed sentence

message: Where would Linear system theory, LTI system theory fit? I think someone needs to verify that it indeed is "used as a synonym" not just "used as a shortform for complex systems theory" :P--Ben 05:54, 19 November 2005 (UTC)
replies: text: Well you can imagine what my opinion on that would be. Linear systems are not "complex systems" if that term is to be salvagable. "Complex system" is a bit of a problematic term since it is used/misused so frequently that it is in danger of becoming meaningless or vacuous. However, it does seem to me that the main thing that has thrust this area into the limelight is the devolopment of non-linear dynamical systems theory and the computers to explore it. That is ultimately what produces the really interesting behaviours, be it homeostasis, multistability or whatever. So, I would argue that linear systems theory should be kept distinct, and really thought of as seperate from complex systems. But I'm sure not everyone would agree. Duracell 20:37, 19 November 2005 (UTC)
replies: text: NOTE: actually, re: linear systems: something that is of technical interesest is linearization, where one makes a linear approximation of a non-linear function at an equilibrium point (i.e. point attractor/repellor) to determine stability. In that sense, linear systems theory and non-linear systems theory are conjunctive. So a link should maybe be added - should this article be a general "overview" article, or should it go into technical details like this? Duracell 20:50, 19 November 2005 (UTC)

text: Yes, I think that is exactly right Duracell 18:32, 28 November 2005 (UTC)
thread_title: Where would Linear system theory fit?