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-- --------------------------------------------------- Bruce Edmonds, Centre for Policy Modelling, Manchester Metropolitan University, Aytoun Bldg., Aytoun St., Manchester, M1 3GH. UK. Tel: +44 161 247 6479 Fax: +44 161 247 6802 http://bruce.edmonds.name/bme_home.html--------------2839456D7457 Content-Type: message/rfc822 Content-Transfer-Encoding: 7bit Content-Disposition: inline
Received: from DEFIANCE_MAIL by AY_DEFIANCE (Mercury 1.21); 5 Mar 96 09:19:15 GMT Return-path: <HANSS@sepa.tudelft.nl> Received: from ehlana.mmu.ac.uk by defiance.mmu.ac.uk (Mercury 1.21) with ESMTP; 5 Mar 96 09:19:03 GMT Received: from sepa.tudelft.nl (actually zon.sepa.tudelft.nl) by ehlana with SMTP (PP); Tue, 5 Mar 1996 09:29:10 +0100 Received: from zondisk.sepa.tudelft.nl (zondisk.sepa.tudelft.nl [130.161.216.6]) by sepa.tudelft.nl (8.7/8.7) with ESMTP id KAA07562 for <B.Edmonds@MMU.AC.UK>; Tue, 5 Mar 1996 10:17:46 +0100 (MET) Received: from ZONDISK/SpoolDir by zondisk.sepa.tudelft.nl (Mercury 1.21); 5 Mar 96 10:30:28 Received: from SpoolDir by ZONDISK (Mercury 1.21); 5 Mar 96 10:30:23 From: Hans-Cees Speel <HANSS@sepa.tudelft.nl> To: Bruce Edmonds pcp <B.Edmonds@MMU.AC.UK> Date: Tue, 5 Mar 1996 10:30:21 MET Subject: Re: The Growth of Structural and Functional Complexity duri Reply-to: hanss@sepa.tudelft.nl Priority: normal X-mailer: Pegasus Mail/Windows (v1.22) Message-ID: <EBDADF5C49@zondisk.sepa.tudelft.nl> X-Mozilla-Status: 0011
> >However, if you are not using Rosen's definition of complexity, > >which one are you using? > > My "definition", which is not really precise enough to satisfy me as a > definition, considers complexity to be the combination of distinction > (variety of distinct components) and connection (linkages between the > components). The larger the variety and the larger the connectivity, the > larger the complexity. For a more detailed discussion, read the following > quote from my paper > (http://pespmc1.vub.ac.be/papers/ComplexityGrowth.html):
Everyone can of course use the definitions or descriptions he wants. I would like to mark for clarity that this description of complexity leaves out: -the disctinctions you can make in kinds of connection patterns [linear versus non-linear between two nodes, and for instance the circularity in the wiring of nodes, etc. etc.] -the question whether the system is programmed in some way, and whether the program is self-writing in some way [the rosen way of complexity if I am right]
> "Let us go back to the original Latin word complexus, which signifies > "entwined", "twisted together". This may be interpreted in the following > way: in order to have a complex you need two or more components, which are > joined in such a way that it is difficult to separate them. Similarly, the > Oxford Dictionary defines something as "complex" if it is "made of (usually > several) closely connected parts". Here we find the basic duality between > parts which are at the same time distinct and connected. Intuitively then, > a system would be more complex if more parts could be distinguished, and if > more connections between them existed.
Let us not forget that the word complexity has grown over the years and has begon to mean many different things. This is the reason that it is good that Francis has defined it [or described]
> More parts to be represented means more extensive models, which require > more time to be searched or computed. Since the components of a complex > cannot be separated without destroying it, the method of analysis or > decomposition into independent modules cannot be used to develop or > simplify such models.
I think this is sometimes true, and sometimes not. Some systems can be very de-composable, others not, and much of this is accounted for in the way the parts are wired together.
This implies that complex entities will be difficult > to model, that eventual models will be difficult to use for prediction or > control, and that problems will be difficult to solve. This accounts for > the connotation of difficult, which the word "complex" has received in > later periods.
For instance [I hope I am not boring you all], in my field of policy science complex is used in situations where political and technological reasoning meet each other in societal decision processes. It is complex, because the rationality of politicians [what are the voters, and the party gonna say] and the rationality of the technitians and the like [this will destroy the environment or this bridge is no solution for traffic problems] are very different.
A decision that has to be made concerning both rationalities [one party is pro the decision to build a bridge, and the other is against for voters reasons, and technitions think it will solve problems, but environmentalists say it is bad] is very complex to follow, to predict, and generally to oversee.
If we see rationalities as nodes, and the interaction of them as connections, that vary over time, we would probably get a comples system, but I am streching the metafor to its limit here:-)
> >Are organisms machines? > >Are they complex? > > > Organisms on the other hand extend over many more scales, from atoms, to > monomers, polymers, organelles, cells, tissues, organs, etc. Moreover, the > connections between the organizations on these different scales are > typically much more complex for organisms than for machines, which are > designed in such a way that the internal structure of the components has > minimal interactions with other components.
don't forget that organisms have descriptions in them [dna, etc], where most machines don't
greetings,
Hans-Cees
Theories come and go, the frog stays [F. Jacob] ------------------------------------------------------- |Hans-Cees Speel School of Systems Engineering, Policy Analysis and management |Technical University Delft, Jaffalaan 5 2600 GA Delft PO Box 5015 The Netherlands |telephone +3115785776 telefax +3115783422 E-mail hanss@sepa.tudelft.nl HTTP://www.sepa.tudelft.nl/~afd_ba/hanss.html featuring evolution and memetics!
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