In: Proceedings of the 12th International Conference on Application and Theory of Petri Nets, 1991, Gjern, Denmark, pages 349-369. June 1991.
Also in: Rozenberg, G.: Lecture Notes in Computer Science, Vol. 674; Advances in Petri Nets 1993, pages 350-370. Springer-Verlag, 1993.
Abstract: In this paper the domain of EN Systems is characterized as a Partial Order, by means of an injective morphism notion. The partial order that is introduced has a behavioural interpretation in the sense that `larger' Systems have `larger' behavioural possibilities. Then some unary operations are defined allowing to add Places and/or Transitions to an existing EN System. On the defined Partial Order the operation of adding a Transition is interpreted as enlarging the behaviour of the System (Extension), while the operation of adding a Place is interpreted as restricting it (Constraint). Some properties of the two operation types are investigated. The newly proposed order and operations are fully consistent with the semantics of EN Systems in terms of Elementary Transition Systems.
Keywords: elementary net system calculus, constraint, extension; adding (of) place(s); adding (of) transition(s); elementary transition systems; net morphisms; unary operations on nets; regions.