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Tracing Complexity Theory ESD.83 – Research Seminar in Engineering Systems P. Ferreira October 2001 Outline Views Definition Approach Applications Early History People Institutions Research Assessment References Views Study of complicated systems:
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Following Complexity Theory ESD.83 – Research Seminar in Engineering Systems P. Ferreira October 2001

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Outline Views Definition Approach Applications Early History People Institutions Research Assessment References

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Views Study of confounded frameworks: A framework is mind boggling when it is made out of numerous parts that interconnect in perplexing ways . ( Joel Moses, “Complexity and Flexibility” ). This definition needs to do with the number and nature of the interconnections. Metric for many-sided nature is measure of data contained in the framework A framework presents dynamic intricacy when circumstances and end results are unpretentious , after some time. ( Peter Senge, “The Fifth Discipline” ). Egs: drastically diverse impacts in, the short-run and the long-run; significantly distinctive impacts locally and in different parts of the framework; evident mediations deliver non-clear outcomes A framework is intricate when it is made out of a gathering of related units (subsystems), for which the degree and nature of the connections is incompletely known . ( Joseph Sussman, “The New Transportation Faculty” ). The general new conduct is hard to foresee, notwithstanding when subsystem conduct is promptly unsurprising. Little changes in inputs or parameters may create huge changes in conduct

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Views Study of muddled frameworks: A mind boggling framework has an arrangement of diverse components so associated or related as to perform a novel capacity not performable by the components alone. ( Rechtin and Maier, “The Art of System Architecting” ). Require diverse critical thinking strategies at distinctive levels of reflection Scientific multifaceted nature identifies with the conduct of plainly visible accumulations of units blessed with the possibility to develop in time . ( Coveney and Highfield, “Frontiers of Complexity” ). This is not quite the same as numerical multifaceted nature (number of scientific operations expected to take care of an issue, utilized as a part of software engineering) Complexity hypothesis and tumult hypothesis both endeavor to accommodate the eccentrics of non-straight element frameworks with a feeling of fundamental request and structure . ( David Levy, “Applications and Limitations of Complexity Theory in Organizational Theory and Strategy” ). Suggestions: example of fleeting consistency however long haul arranging outlandish, sensational change out of the blue, associations can be tuned to be more creative and versatile

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Views

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Definition The Newtonian Paradigm is based on Cartesian Reductionism: Machine Metaphor and Cartesian Dualism (Descartes): Body is an organic machine; mind as something separated from the body; Intuitive idea of machine: developed from unmistakable parts and can be lessened to those parts without losing its machine-like character: Cartesian Reductionism The Newtonian Paradigm and the three laws of movement: General Laws of movement, utilized as the present day's establishment logical technique. Progress is the focal point of the structure, which prompts direction Complexity results from disappointment of the Newtonian Paradigm to be bland: Complex and straightforward frameworks are disjoint classes that include all of nature But this present reality is comprised of complex things and the universe of basic instruments is imaginary and made by science. Examinations include decreasing the framework to its parts and after that contemplating those parts in a connection figured by How is science done? Faculties (watch the world) + Mental action (bode well out of that tangible data). Encode normal framework (NS) into formal framework (FS); control FS to mirror the causal change in the NS. From the FS infer a suggestion that relates to the causal occasion in the FS; interpret the FS and check its accomplishment in speaking to the causal occasion in the NS

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Definition of Complexity: “…The world, from which we single out some littler part, the NS, is changed over into a FS that our brain can control and we have a model. The world is mind boggling. The FS we decided to attempt to catch it must be halfway effective . For a considerable length of time we were fulfilled by the Newtonian Paradigm as the FS, disregarded there being and encoding and unraveling, and bit by bit started to change the philosophy so that the Newtonian Paradigm really supplanted or turned into this present reality. As we looked all the more profoundly into the world we concocted perspectives that the Newtonian Paradigm neglected to catch. At that point we required a clarification. Unpredictability was conceived! This effectively can be formalized. It has extremely significant meaning…” “… Complexity is the property of a genuine framework that is show in the powerlessness of any one formalism being sufficient to catch every one of its properties . It obliges that we find particularly diverse methods for interfacing with frameworks. Particularly diverse as in when we make effective models, the formal frameworks expected to depict each unmistakable perspective are NOT resultant from each other…” Bob Rosen and Don Mikulecky , Professors of Physiology Medical College of Virginia Commonwealth University

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Definition Implications of this definition: An intricate framework is non-fragmentable . On the off chance that it were it would be a machine. Their decrease to parts annihilates critical framework qualities irreversibly An intricate framework includes genuine segments that are particular from its parts .There are useful segments characterized by the framework which definition rely on upon the framework's connection. Outside the framework they have no significance. In the event that expelled from the framework it looses its unique character Complex frameworks have models, scientific or engineered. Be that as it may, the instruments contrast . On the off chance that a manufactured model can supplant an expository models, the framework is fragmentable No “largest model” . On the off chance that there were a biggest model, every single other model could be gotten from it and fragmentability would come about Causalities in the framework are blended when disseminated over the parts. The way of causality obliges shut circles of avoided in the Newtonian Paradigm The vital qualities of the framework are past algorithmic definition or acknowledgment : a way to disprove Church's proposition (“…All the models of calculation yet created, and each one of those that may be produced later on, are comparable in force. We won't ever locate an all the more intense model...”)

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Complexity Disorder Definition Ideas identified with Complexity: Size : Egs “the size of a genome“; “the number of species in an ecology”. Size is sign of trouble in managing the framework. Be that as it may, for unpredictability, such parts should be between related Ignorance : Eg”the cerebrum is excessively perplexing for us, making it impossible to understand“.Complexity is the reason for lack of awareness. Can't totally relate the two (other noteworthy reasons?) Minimum Description Length : Kolmogorov Complexity is the base conceivable length of a depiction in some dialect (more often than not that of a Turing machine) Variety : Eg “this species markings are unpredictable because of their awesome variety”. Assortment is essential for many-sided quality however it is not adequate for it (Dis)Order : Complexity is mid-point in the middle of request and issue

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Definition “… Complexity is that property of a dialect expression which makes it hard to detail its general conduct , notwithstanding when given verging on complete data about its nuclear segments and their between relations…" Relationship to more particular meanings of multifaceted nature: Computational Complexity : measure of computational assets expected to take care of a class of issues. Does not have the trouble of giving the project itself Bennett's Logical Depth : computational assets to ascertain the aftereffects of a system of negligible length Lã¶fgren's Interpretation and Descriptive Complexity : the joined procedures of elucidation and portrayal. Eg: understanding: disentangling of the DNA into the powerful proteins; portrayal: handle the consequence of generation and determination on the data there encoded Kauffman's number of clashing requirements : many-sided quality is the quantity of clashing limitations. This speaks to the trouble of determining a fruitful developmental walk given the imperatives Bruce Edmonds , Senior Research Fellow in Logic and Formal Methods Center for Policy Modeling, Manchester Metropolitan University, UK

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Approach Abstraction , Modularity and Scales Eg from Physics: Matter {- i ( 2  2 i )/(2m e )-  i ( 2  2 j )/(2m n )+e 2/(4 0 ) i1,i2 1/|r i1 - r i2 |+ +z 2 e 2/(4 0 )  j1,j2 1/|R j1 - R j2 |-ze 2/(4 0 )  i,j 1/|r i - R j | } =E But can't illuminate scientifically regardless of the possibility that i=2 and j=1 (Helium) What to do? Portray the framework's conduct at an alternate scales Eg: particles (mass, charge, shafts, symmetries,…) Or use Computer Simulation (real instrument)

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Approach But PCs have constrained expressive force . PCs with 32 bits have ventures of no less than 2.328 - 10 . For a few frameworks, a distinction of this greatness in the info conditions lead to altogether different results Eg: M. Feigenbaum investigations of populace development models Population t = GrowthRate*Population t (1-Population t-1 ) Feigenbaum Constant: 4.6692016… Growth Rate

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Approach But the Feigenbaum steady shows up in numerous different connections Eg: the Mandelbrot Set Equation: Z(n+1)=Z(n) 2 +C, C and Z fanciful numbers Mapping: speaks to the quantity of emphasess requirement for |Z(n)|>2 The significance of the Feigenbaum consistent: It is an invariant

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Approach Dissipation of the introductory conditions: Eg: Th