Complex Adaptive System
From CasGroup
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| - | A '''Complex Adaptive System''' (CAS) is a special case of a [[Complex System|complex system]] | + | A '''Complex Adaptive System''' (CAS) is a special case of a [[Complex System|complex system]] which is also [[Adaptive_System|adaptive]], i.e. it has the ability to change and [[Adaptation|adapt itself]] to the environment. Typically it consists of a large number of interacting adaptive [[Agent|agents]]. CASs are used to understand events, objects, and processes in their relationship with each other. They are 'complex' - they are diverse and made up of multiple interconnected elements - and 'adaptive' - they have the capacity to change and learn from experience. They are systems where a lot of individual adaptive agents interact and communicate with each other: complex [[Multi-Agent System|MAS]] with adaptive agents. The agents of a CAS learn and change as they interact with each other. The name '''complex adaptive systems''' has been coined at the interdisciplinary [http://www.santafe.edu Santa Fe Institute] (SFI), by John H. Holland, Murray Gell-Mann and others. John H. Holland is one of the inventors of evolutionary computation and [[Genetic Algorithm|genetic algorithm]]s, Nobel Prize laureate Murray Gell-Mann discovered quarks. |
== Definitions == | == Definitions == | ||
| - | In general the term Complex Adaptive System (CAS) is simply used for every system and society that consists of a | + | CAS are an attempt to find a new, unified way of thinking about nature, human social behavior, life and the universe itself. In general the term Complex Adaptive System (CAS) is simply used for every system and society that consists of a |
large number of mutually interacting [[Agent|agents]]. A CAS is a complex, often self-similar collectivity of interacting adaptive | large number of mutually interacting [[Agent|agents]]. A CAS is a complex, often self-similar collectivity of interacting adaptive | ||
agents. The study of CAS focus on the [[Emergence|emergent]], [[Self-Organization|self-organizing]] and macroscopic properties of these [[Complex System|complex systems]]. Various definitions have been offered by different researchers: | agents. The study of CAS focus on the [[Emergence|emergent]], [[Self-Organization|self-organizing]] and macroscopic properties of these [[Complex System|complex systems]]. Various definitions have been offered by different researchers: | ||
*John H. Holland | *John H. Holland | ||
| - | :''A Complex Adaptive System (CAS) is a dynamic network of many agents (which may represent cells, species, individuals, firms, nations) acting in parallel, constantly acting and reacting to what the other agents are doing. The control of a CAS tends to be highly dispersed and decentralized. If there is to be any coherent behavior in the system, it has to arise from competition and cooperation among the agents themselves. The overall behavior of the system is the result of a huge number of decisions made every moment by many individual agents.'' (Source: M. Waldrop's book about "Complexity: The Emerging Science at the Edge of Order and Chaos") | + | :''A Complex Adaptive System (CAS) is a dynamic network of many agents (which may represent cells, species, individuals, firms, nations) acting in parallel, constantly acting and reacting to what the other agents are doing. The control of a CAS tends to be highly dispersed and decentralized. If there is to be any coherent behavior in the system, it has to arise from competition and cooperation among the agents themselves. The overall behavior of the system is the result of a huge number of decisions made every moment by many individual agents.'' (Source: M. Waldrop's book about "Complexity: The Emerging Science at the Edge of Order and Chaos"). According to John Holland, a complex adaptive system "can function (or continue to exist) only if it makes a continued adaptation to an environment that exhibits perpetual novelty" (see his article [http://www.santafe.edu/media/bulletin_articles/summer_fall1987v2n1.pdf Complex Adaptive Systems: A Primer]. It interacts with the environment in a game-like way to explore the environment. It occupies or exploits a [[Niche|niche]] in the environment. And there is a tradeoff between [[Exploitation_and_Exploration|exploration and exploitation]]. |
*Kevin Dooley | *Kevin Dooley | ||
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== Examples == | == Examples == | ||
| + | CAS can be found in cogntitive psychology, artificial intelligence, | ||
| + | scociology, ecology, biology, economics, and genetics. | ||
Examples of CAS with the corresponding agents in parentheses are: | Examples of CAS with the corresponding agents in parentheses are: | ||
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* immune systems (antibodies) | * immune systems (antibodies) | ||
* biological cells (proteins) | * biological cells (proteins) | ||
| - | * social systems (persons) | + | * [[Social system|social systems]] (persons) |
| + | * [[Political system|political systems]] (parties) | ||
| - | Another example is the stock market in which adaptive agents (traders) learn day-by-day and change their actions as they go. A good example is the immune system. It starts off simple but learns how to prevent you from getting complex illnesses. Other examples of complex adaptive systems include the social insect and | + | Another example is the stock market in which adaptive agents (traders) learn day-by-day and change their actions as they go. A good example is the immune system. It starts off simple but learns how to prevent you from getting complex illnesses. Other examples of complex adaptive systems include the social insect and ant colonies, the biosphere and the [[ecosystem]], the brain, the cell and the developing embryo, manufacturing businesses and any social human group-based endeavour in a cultural and [[Social system|social system]] such as political parties or [[Social network|communities and social networks]]. There are close connections between the field of CAS and [[ALife]]. In both areas the principles [[Emergence|emergence]] and [[Self-Organization|self-organization]] are very important. |
The terms '''complex adaptive systems''', '''complexity science''' or '''the sciences of complexity''' are often used to describe the loose academic field that has grown up around the study of complex adaptive systems. Complexity science is like [[Systems Theory|systems theory]] not a single theory - it encompasses more than one theoretical framework and is highly interdisciplinary, seeking the answers to some fundamental questions about living, adaptable, changeable systems. | The terms '''complex adaptive systems''', '''complexity science''' or '''the sciences of complexity''' are often used to describe the loose academic field that has grown up around the study of complex adaptive systems. Complexity science is like [[Systems Theory|systems theory]] not a single theory - it encompasses more than one theoretical framework and is highly interdisciplinary, seeking the answers to some fundamental questions about living, adaptable, changeable systems. | ||
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environment. The more successful rules are selected, whereas the less | environment. The more successful rules are selected, whereas the less | ||
successful rules are deleted. | successful rules are deleted. | ||
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| + | == Principles and Theorems == | ||
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| + | A set of [[Basic_System_Theory|basic principles]] is well known. | ||
| + | Yet a theory, a set of [[Theorem|theorem]]s or "calculus" for | ||
| + | these systems would be desirable. John H. Miller and Scott E. Page | ||
| + | write in their book "Complex Adaptive Systems": "We hope that there | ||
| + | is a complex systems equivalent of Newton's Laws of Motion". | ||
| + | Is there any? | ||
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| + | [[Cellular Automata]] and Agent-Based Systems are commonly used | ||
| + | to model and simulate CAS. Is there any calculus for their | ||
| + | complex combination of [[Iteration|iteration]] and interaction? | ||
| + | Or are they [[Computational_irreducibility|computationally irreducible]], | ||
| + | which means it is impossible in principle to shortcut or predict their | ||
| + | behavior? | ||
== CAS and MAS == | == CAS and MAS == | ||
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== Articles == | == Articles == | ||
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| + | CAS in general (John H. Holland) | ||
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| + | * John H. Holland, [http://www.santafe.edu/media/bulletin_articles/summer_fall1987v2n1.pdf Complex Adaptive Systems: A Primer] | ||
| + | * John H. Holland, [http://www.the-scientist.com/article/display/54988/ Biology's Gift to a Complex World] | ||
Ecosystems and Biospheres (Simon A. Levin, Timothy M. Lenton) | Ecosystems and Biospheres (Simon A. Levin, Timothy M. Lenton) | ||
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* Stephanie Forrest, "Emergent Computation: Self-organizing, collective, and cooperative phenomena in natural and artificial computing networks", Physica D 42 (1990) 1-11 | * Stephanie Forrest, "Emergent Computation: Self-organizing, collective, and cooperative phenomena in natural and artificial computing networks", Physica D 42 (1990) 1-11 | ||
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| + | == Books == | ||
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| + | * John H. Miller & Scott E. Page, Complex Adaptive Systems: An Introduction to Computational Models of Social Life, Princeton University Press, 2007 | ||
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| + | * M. Waldrop, Complexity: The Emerging Science at the Edge of Order and Chaos, Simon & Schuster, 1992 | ||
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| + | * John Holland, Hidden Order: How Adaptation Builds Complexity, Basic Books, 1996 | ||
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| + | * John H. Holland, Emergence: From Chaos To Order, Basic Books, 1999 | ||
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| + | more can be found in this [http://www-users.cs.york.ac.uk/susan/int/books.htm#soc list] | ||
==External links== | ==External links== | ||
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* [http://www.cs.iastate.edu/~honavar/alife.isu.html CAS Group at Iowa State University] | * [http://www.cs.iastate.edu/~honavar/alife.isu.html CAS Group at Iowa State University] | ||
* [http://www.casresearch.com/ CAS Research Site by Mark Voss] | * [http://www.casresearch.com/ CAS Research Site by Mark Voss] | ||
