"The form of stability apparent in an adaptive system" (G. PASK, 1961a, p.115).
Adaptive systems possess controllers which are themselves adaptive, i.e. able to counteract a wide variety of environmental or invironmental perturbations.
Ultrastable systems are able – up to a point- to change their internal functional organization and structures in order to adapt to external disturbances. However such changes must respect global coherence: "If the whole is at a state of equilibrium, each part must be in a state of equilibrium in the conditions provided by the others" (W.R. ASHBY, p.82).
And: "No state (of the whole) can be a state of equilibrium unless it is acceptable to every one of the component parts, each acting in the conditions given by the others" (p.83).
Ultrastability is thus the oscillating stability of the set of critical interconnected variables in a system, obtained through their repeated reciprocal action.
To demonstrate these characteristics, ASHBY constructed his well known "Homeostat", an experimental cybernetic machine which shows an enormous variability potential, through oscillations… but tends to oscillating stability within limits.
In a concrete system, ultrastability requires self-regulation and therefore it must contain a good model of itself.
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To cite this page, please use the following information:
Bertalanffy Center for the Study of Systems Science (2020). Title of the entry. In Charles François (Ed.), International Encyclopedia of Systems and Cybernetics (2). Retrieved from www.systemspedia.org/[full/url]
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