Complex System Classification
Magee, C.L., de Weck, O.L., 2004. "Complex System Classification." Toulouse, France: Proceedings of the 14th Annual International Symposium of the International Council on Systems Engineering (INCOSE), 20 – 24 June 2004.
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Magee and de Weck examine many possible methods that include: degree of complexity, branch of the economy that produced the system, realm of existence (physical or in thought), boundary, origin, time dependence, system states, human involvement / system control, human wants, ownership and functional type. They conclude by proposing a functional classification method that sorts systems by their process: transform, transport, store, exchange, or control and by the entity that they operate on: matter, energy, information and value.