Sometimes, where a complex problem can be illuminated by many tools, one can be forgiven for applying the one he knows best. - Robert E. Machol

Everyone knows what engineering is. All that's left is to define systems, and I'm not fool enough to do that.

[This set of inputs [can be defined] as 1) input which is always the same or is of many types, 2) input which occurs periodically (or very infrequently), and 3) input which does or does not seek to destroy the system. Their rationale for developing the classification was to aid in the definition of steps to be followed in order to find the] solution of the problem of a large-scale or complex system.

Every large-scale system is an . The automatic factory, the vehicular-traffic system, any military system- in the design of all these systems, primary attention should be given to the flow of information about the elements of the system.