9.   Concepts


9.1     Social Cost

The social cost of a product represents the total human time which has to be spent for the production of the product, as well as for the production of all the necessary production resources. This definition is closely related to the concept of "value" in classical economic theory: A. Smith, D. Ricardo, K. Marx, (see also http://en.wikipedia.org/wiki/Labor_theory_of_value). However, here we are interested in the "social cost" as a stand-alone concept, regardless from both the definition of "value" and the relevant theoretical debate.


9.2     Cost of information

The cost of information constitutes part of the social cost: specifically is the part that concerns all the information production activities related to the production of either the product or its production resources. The concept of "information value"—closely related to "cost of information"—is extensively discussed in [Veneris Y., 1986, The informatics revolution, New Frontiers Publications (in Greek), pp.180-189].


9.3     Development

Within the framework of complex systems, the term "development" has a specific meaning: denotes a spontaneous dynamic process of self-creation, under the catalytic influence of the environment, where structures of increasing complexity are successively created according to a bottom-up recursive process (e.g. in the living systems: proteins ® tissues ® organs). The "development" saves information, as in each developmental phase different types of the system's structural units derive from the differentiation of already created types (basic type ® differentiation ® composition of the differentiated types). The development of the living organisms is referred to as "embryogeny".


Bar‑Yam Y., 1997, Dynamics of Complex Systems. Addison Wesley, Reading, Massachusetts, pp. 621-625



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9.4     Evolution

A system "evolves" if it is subjected to random variations while it is successively stabilized in the variations that improve its functionality. A characteristic paradigm of evolution is the  evolution of a population of reproduced organisms, where random variations of the structure of descendants determine the probability of further reproduction: organisms better adapted to the environment—consequently more "sustainable"—have higher probability to be reproduced, spreading this way their structure in the population. This process, repeated recursively, results in the production of organisms of increasing adaptation and potentially of higher complexity.


Bar‑Yam Y., 1997, Dynamics of Complex Systems. Addison Wesley, Reading, Massachusetts, pp. 531-542



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9.5     Emergent properties

A system could have properties that derive—potentially implicitly—from the interdependence of its parts without being properties of the parts each one viewed in isolation. These properties are characterized as "emergent".


Bar‑Yam Y., 1997, Dynamics of Complex Systems. Addison Wesley, Reading, Massachusetts, pp. 10-12



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9.6     Variability and Complexity

We define as "variability" the number of the potential discrete states of a system. Variability depends on the scale in which the system is observed, as slight alterations which are observable—consequently make possible the identification of discrete states—in the small scale, are not observable in the large scale. As a consequence, variability tends to decrease with the scale of observation. The "complexity" of the system, defined as the logarithm of the value of variability, determines the quantity of the information contained in the system. Due to this definition, complexity also depends on the scale of observation.


Bar‑Yam Y., 1997, Dynamics of Complex Systems. Addison Wesley, Reading, Massachusetts, pp. 12-14



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9.7     Adaptability

We call "adaptability" the possibility of a system to be dynamically transformed, responding to stimuli coming from the environment, in order to either maintain or acquire specific features. Such features can be related to either the notion of sustainability, as it happens in living systems, or desirable properties in artificial systems.




9.8     Epistasis: synergy and antagonism

A system shows "epistasis" if the combined result of the function of its parts quantitatively differs from the additive result of the function of the same parts each one functioning independently from the others. If the combined result exceeds the additive one then the epistasis is characterized as "synergistic", whereas on the opposite case it is characterized as "antagonistic".






9.9     Network Organization

A network organization is characterized by the existence of many peer interlinked units which perform in common a complex task, while only a small part of that task corresponds to each unit. The function of each unit is not explicitly predefined as it depends on variable conditions affecting the system. Consequently, a system having network organization may exhibit high adaptability. The efficiency of network organization is based more on the linkage of the units, and the consequent synergistic effects, than on the efficiency of each unit viewed in isolation. A system having network organization may cope with partial failures better than a hierarchically organized one, as failure of some units may be remedied by an appropriate adaptation of the function of the rest units.

Here, as well as in every reference to the terms "network" or  "network paradigm", we use the aforementioned specific meaning of the term "network organization". The broader concept of a "network" may also include networks having dissimilar units or links: http://necsi.org/guide/concepts/network.html.



9.10   Integration

We assume that different functions formulate an "integrated system" if they are combined in a way such that the result of each function reinforces the result of others (see also "synergy") supporting the overall system's functionality. Integrated systems exhibit high autonomy: to a large degree provide by themselves the conditions required for their own performance, reducing in this way dependence on external factors. The concept of "integration", in this context, is closely related to the complex systems theory.


9.11   Sustainability

The notion of "sustainability" describes the characteristic property of a system to be self-preserved by maintaining the resources required for its performance. The term "sustainability" usually refers to either social, economic, constitutional or environmental systems.






9.12   Self-organization

A system exhibits "self-organization" if properties related to its function, behavior or structure derive from internal system's dynamics as emergent properties. Self-organization is related to adaptability, as the aforementioned properties may concern the interaction of the system with its environment.







9.13   Parallelization

An obvious consequence of the simultaneous (parallel in time) realization of different processes of an either natural or artificial system is the possibility to acquire the overall result of these processes in a time shorter than the time required in the case of the sequential (serial in time) realization. A less obvious consequence concerns the effect of the interactions among synchronous phases of the parallel processes on the overall result itself. The development of the living systems is based on such interactions.