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This article describes complex system as a type of system. For other meanings, see complex systems. This article describes complex systems as field of Science. For other meanings see Complex system.

A complex system is a system composed of interconnected parts that as a whole exhibit one or more properties (behavior among the possible properties) not obvious from the properties of the individual parts. System (from Latin systēma, in turn from Greek systēma is a set of interacting or interdependent Entities, real or abstract A system’s complexity may be of one of two forms: disorganized complexity and organized complexity. In general usage complexity often tends to be used to characterize something with many parts in intricate arrangement In general usage complexity often tends to be used to characterize something with many parts in intricate arrangement [1] In essence, disorganized complexity is a matter of a very large number of parts, and organized complexity is a matter of the subject system (quite possibly with only a limited number of parts) exhibiting emergent properties. For other uses see Emergence (disambiguation, Emergent, and Emergency. Examples of complex systems include ant colonies, ants themselves, human economies, climate, nervous systems, cells and living things, including human beings, as well as modern energy or telecommunication infrastructures. System (from Latin systēma, in turn from Greek systēma is a set of interacting or interdependent Entities, real or abstract An ant colony is an underground Lair where Ants live Colonies consist of a series of underground chambers connected to each other and the surface of the earth by Ants are social Insects of the family Formicidae and along with the related families of Wasps and Bees belong to the order Human beings, humans or man (Origin 1590–1600 L homō man OL hemō the earthly one (see Humus Economics is the social science that studies the production distribution, and consumption of goods and services. Climate encompasses the temperatures humidity rainfall atmospheric particle count and numerous other meteorogical factors in a given region over long periods of The nervous system is a Network of specialized cells that communicate information about an animal's surroundings and itself The cell is the structural and functional unit of all known living Organisms It is the smallest unit of an organism that is classified as living and is often called Indeed, many systems of interest to humans are complex systems.

Complex systems are studied by many areas of natural science, mathematics, and social science. In Science, the term natural science refers to a naturalistic approach to the study of the Universe, which is understood as obeying rules or law of Mathematics is the body of Knowledge and Academic discipline that studies such concepts as Quantity, Structure, Space and The social sciences comprise academic disciplines concerned with the study of the social life of human groups and individuals including Anthropology, Communication studies Fields that specialize in the interdisciplinary study of complex systems include systems theory, complexity theory, systems ecology, and cybernetics. Systems theory is an Interdisciplinary field of Science and the study of the nature of Complex systems in Nature, Society, and Systems ecology is an Interdisciplinary field of Ecology, taking a holistic approach to the study of ecological systems especially Ecosystems Cybernetics is the interdisciplinary study of the Structure of Complex systems especially Communication processes control mechanisms and Feedback

Contents

Overview

A complex system is any system featuring a large number of interacting components, whose aggregate activity is nonlinear and typically exhibits hierarchical self-organization under selective pressures. System (from Latin systēma, in turn from Greek systēma is a set of interacting or interdependent Entities, real or abstract [2] Now the term complex systems has multiple meaning:

Various informal descriptions of complex systems have been put forward, and these may give some insight into their properties. System (from Latin systēma, in turn from Greek systēma is a set of interacting or interdependent Entities, real or abstract Science (from the Latin scientia, meaning " Knowledge " or "knowing" is the effort to discover, and increase human understanding This article describes complex systems as field of Science. For other meanings see Complex system. The word paradigm ( Greek:παράδειγμα (paradigmacomposite from para- and the verb δείχνυμι "to show" as a whole -roughly- meaning "example" In general usage complexity often tends to be used to characterize something with many parts in intricate arrangement A special edition of Science about complex systems [3] highlighted several of these:

History

Although one can argue that humans have been studying complex systems for thousands of years, the modern scientific study of complex systems is relatively young when compared to areas of science such as physics and chemistry. Physics (Greek Physis - φύσις in everyday terms is the Science of Matter and its motion. Chemistry (from Egyptian kēme (chem meaning "earth") is the Science concerned with the composition structure and properties The history of the scientific study of these systems follows several different strands.

In the area of mathematics, arguably the largest contribution to the study of complex systems was the discovery of chaos in deterministic systems, a feature of certain dynamical systems that is strongly related to nonlinearity. Mathematics is the body of Knowledge and Academic discipline that studies such concepts as Quantity, Structure, Space and In Mathematics, chaos theory describes the behavior of certain dynamical systems – that is systems whose state evolves with time – that may exhibit dynamics that Determinism is the philosophical Proposition that every event including human cognition and behaviour decision and action is causally determined Dynamical systems theory is an area of Applied mathematics used to describe the behavior of complex Dynamical systems usually by employing Differential This article describes the use of the term nonlinearity in mathematics [4] The study of neural networks was also integral in advancing the mathematics needed to study complex systems. Traditionally the term neural network had been used to refer to a network or circuit of biological neurons.

The notion of self-organizing systems is tied up to work in nonequilibrium thermodynamics, including that pioneered by chemist and Nobel laureate Ilya Prigogine in his study of dissipative structures. Self-organization is a process of Attraction and repulsion in which the internal organization of a System, normally an open system, increases Non-equilibrium thermodynamics is a branch of Thermodynamics concerned with studying Time -dependent Thermodynamic systems irreversible transformations A chemist is a Scientist trained in the Science of Chemistry. This is a list of Nobel Prize Laureates awarded for their outstanding contributions to Humanitarian causes for Peace, work in Literature Ilya Viscount Prigogine (Илья́ Рома́нович Приго́жин ( January 25, 1917 &ndash May 28, 2003) was a Russian Another meaning of "dissipative system" is one that dissipates heat see heat dissipation.

Types of complex systems

Chaotic systems

Main article: Chaos theory

For a dynamical system to be classified as chaotic, most scientists will agree that it must have the following properties:

  1. it must be sensitive to initial conditions,
  2. it must be topologically mixing, and
  3. its periodic orbits must be dense. In Mathematics, chaos theory describes the behavior of certain dynamical systems – that is systems whose state evolves with time – that may exhibit dynamics that

Sensitivity to initial conditions means that each point in such a system is arbitrarily closely approximated by other points with significantly different future trajectories. Thus, an arbitrarily small perturbation of the current trajectory may lead to significantly different future behaviour.

Complex adaptive systems

Main article: Complex adaptive system

Complex adaptive systems (CAS) are special cases of complex systems. Complex adaptive systems are special cases of Complex systems They are complex in that they are diverse and made up of multiple interconnected elements and adaptive They are complex in that they are diverse and made up of multiple interconnected elements and adaptive in that they have the capacity to change and learn from experience. Adaptive behavior is a type of Behavior that is used to adapt to another type of behavior or situation Examples of complex adaptive systems include the stock market, social insect and ant colonies, the biosphere and the ecosystem, the brain and the immune system, the cell and the developing embryo, manufacturing businesses and any human social group-based endeavour in a cultural and social system such as political parties or communities. A stock market, or (equity market is a private or public market for the trading of company Stock and derivatives of company Ants are social Insects of the family Formicidae and along with the related families of Wasps and Bees belong to the order The biosphere is the broadest level of ecological study the global sum of all Ecosystems. An ecosystem is a natural unit consisting of all plants animals and micro-organisms( Biotic factors in an area functioning together with all of the non-living physical ( The brain is the center of the Nervous system in animals All Vertebrates and the majority of Invertebrates have a brain An immune system is a collection of mechanisms within an Organism that protects against Disease by identifying and killing Pathogens and Tumor The cell is the structural and functional unit of all known living Organisms It is the smallest unit of an organism that is classified as living and is often called An embryo (from Greek:, plural, lit "that which grows" from en- "in" + bryein "to swell be full" is a multicellular Manufacturing (from Latin manu factura, "making by hand" is the use of tools and labor to make things for use or sale Social structure is a term frequently used in Sociology and Social theory — yet rarely defined or clearly conceptualised (Abercrombie et al A political party is a Political organization that seeks to attain and maintain political power within Government, usually by participating in electoral In biological terms a community is a group of interacting Organisms sharing an environment.

Nonlinear system

Main article: Nonlinearity

A nonlinear system is one whose behavior can't be expressed as a sum of the behaviors of its parts (or of their multiples. This article describes the use of the term nonlinearity in mathematics ) In technical terms, the behavior of nonlinear systems is not subject to the principle of superposition. In Physics and Systems theory, the superposition principle, also known as superposition property, states that for all Linear systems Linear systems are subject to superposition. A linear system is a mathematical model of a System based on the use of a Linear operator.

Topics on complex systems

Features of complex systems

Complex systems in nature have the following features.

Boundaries are difficult to determine
It can be difficult to determine the boundaries of a complex system. The decision is ultimately made by the observer.
Complex systems are open
Complex systems in nature are usually open systems — that is, they exist in a thermodynamic gradient and dissipate energy. In Physics, thermodynamics (from the Greek θερμη therme meaning " Heat " and δυναμις dynamis meaning " In other words, complex systems are usually far from energetic equilibrium: but despite this flux, there may be pattern stability. In Thermodynamics, a thermodynamic system is said to be in thermodynamic equilibrium when it is in thermal equilibrium Mechanical equilibrium, and See synergetics. Synergetics is an interdisciplinary science explaining the formation and Self-organization of patterns and structures in open systems far from thermodynamic equilibrium
Complex systems have a memory
The history of a complex system may be important. Because complex systems are dynamical systems they change over time, and prior states may have an influence on present states. Dynamical systems theory is an area of Applied mathematics used to describe the behavior of complex Dynamical systems usually by employing Differential More formally, complex systems often exhibit hysteresis. A system with hysteresis can be summarised as a system that may be in any number of states independent of the inputs to the system
Complex systems may be nested
The components of a complex system may themselves be complex systems. For example, an economy is made up of organisations, which are made up of people, which are made up of cells - all of which are complex systems. Economics is the social science that studies the production distribution, and consumption of goods and services. An organisation (or organization &mdash see spelling differences) is a social arrangement which pursues collective goals which controls its own performance and The term person is used in Common sense to mean an individual Human being. The cell is the structural and functional unit of all known living Organisms It is the smallest unit of an organism that is classified as living and is often called
Dynamic network of multiplicity
As well as coupling rules, the dynamic network of a complex system is important. Small-world or scale-free networks which have many local interactions and a smaller number of inter-area connections are often employed. A scale-free network is a network whose Degree distribution follows a Power law, at least asymptotically Natural complex systems often exhibit such topologies. In the human cortex for example, we see dense local connectivity and a few very long axon projections between regions inside the cortex and to other brain regions. The cerebral cortex is a structure within the Brain that plays a key role in Memory, Attention, perceptual Awareness, Thought, An axon or nerve fiber is a long slender projectionof a nerve cell or Neuron, that conducts electrical impulses away from the neuron's Cell
May produce emergent phenomena
Complex systems may exhibit behaviors that are emergent, which is to say that while the results may be deterministic, they may have properties that can only be studied at a higher level. For other uses see Emergence (disambiguation, Emergent, and Emergency. For example, the termites in a mound have physiology, biochemistry and biological development that are at one level of analysis, but their social behavior and mound building is a property that emerges from the collection of termites and needs to be analysed at a different level. The termites are a group of Social Insects usually classified at the taxonomic rank of order Isoptera (but see also taxonomy In Biology, Psychology and Sociology social behavior is behavior directed towards society or taking place between members of the same species
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. The butterfly effect is a phrase that encapsulates the more technical notion of sensitive dependence on initial conditions in Chaos theory. In linear systems, effect is always directly proportional to cause. See nonlinearity. This article describes the use of the term nonlinearity in mathematics
Relationships contain feedback loops
Both negative (damping) and positive (amplifying) feedback are often found in complex systems. Feedback is a circular causal Process whereby some proportion of a system's output is returned (fed back to the Input. The effects of an element's behaviour are fed back to in such a way that the element itself is altered.

See also

References

  1. ^ Weaver, Warren (1948), “Science and Complexity”, American Scientist 36: 536 (Retrieved on 2007-11-21. An agent-based model (ABM is a Computational model for simulating the actions and interactions of autonomous individuals in a network with a view to assessing their Another meaning of "dissipative system" is one that dissipates heat see heat dissipation. In the Systems sciences the term system equivalence is the notion that a Parameter or Component of a System behaves in a similar way as a parameter Systems theory is an Interdisciplinary field of Science and the study of the nature of Complex systems in Nature, Society, and ), <http://www.ceptualinstitute.com/genre/weaver/weaver-1947b.htm> 
  2. ^ Luis M. Rocha, 1999.
  3. ^ Science Vol. 284. No. 5411 (1999)]
  4. ^ History of Complex Systems

Further reading

External links

Dictionary

complex system

-noun

  1. specific kind of system, which a certain complexity
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