System Definition


A system is:

(J.L. Lemoigne. La Théorie du Système Général, PUF, 1977


To be fully specified according to the above definition, a system must be described from the point of view of its structure, its evolution, and its functions. We can represent a system by its projection on three axes:

  1. Static: structure, data, memory, states.
  2. Dynamic: evolution, transitions, synchronisation, events.
  3. Algorithmic: functions, transformations.

(Jöel André & Pierre-Marie Delpech. Objects in Europe. Summer 1994).


System comes from Greek: Syn Histemi. I put together.

A system is a set of interrelated things.

Aristotle told us that relation comes from interaction or function.

Interaction happens through interfaces.

Functions do have a "signature".