Petri Nets with Synchronous Channels Applied to a Sociological Example
Sven Heitsch, Marcel Martens, and Daniel Moldt
Address
University of Hamburg,Department of Computer Science
Vogt-Kölln-Straße 30,
22527 Hamburg,
Germany
phone: +49 40 42883 2247,
fax: +49 40 42883 2246
email: {5heitsch, 5martens, moldt}@informatik.uni-hamburg.de
Abstract
Usually sociological models are not executable. Formalizing sociological models is a problem itself. If one gives it a try, the question for the adequate modeling approach and technique comes up immediately. The presentation reports on the formal modeling and visualization of the ideas of a sociological theory with Petri net theory.The Garbage Can Model of Organizational Choice ([CMO 72]) refers to organizations as organized anarchies. Bounded rationality leads to ambiguous decision situations. [CMO 72] is a fundamental contribution to behavioristic organizational theory. It has been and still is widely received in sociology.
Petri nets offer formal semantics, graphical representation, means to model concurrency, and immediate executability and, thus, meet the basic requirements for modeling artificial societies. Reference Nets by [Kummer 98] are a high-level Petri net formalism that offers dynamic net instances, net references, and synchronous communication (see [Christensen and Hansen 92]). These nets can be drawn and executed with Renew, the Reference Net Workshop ([Renew 99]).
In the context of the Socionics project at the University of Hamburg a well known sociological model has been used to investigate on the abilities of Petri nets as a formalism to model such theories. A generalized version of the original Garbage Can Model ([CMO 72]) which was described by [Masuch and LaPotin 89] has been modeled with Reference Nets and executed with Renew. In the presentation a net model with four pages which communicate via synchronous channels is demonstrated. The talk will concentrate on the special importance of synchronous channels for the modeling. The advantages and disadvantages of such concept for building sociological models will be discussed.
The main result is that synchronous channels are a very powerful mechanism. Especially in the context of object-orientation they have proven to reduce the expenditure of coordinating different nets with each other and, thus, make the drawing overhead smaller. However, a major drawback is the potential misuse of such a strong concept. In complex cases there is the danger of losing control of all the channels and reducing the clearness of the Petri net model.
A more advanced model that covers the entire Garbage Can Model of Organizational Choice consists out of 10 pages. These pages also have a much higher complexity. This model is certainly beyond the time scale of the presentation. However, it is used to reflect on the principle problems of the technique and the approach in general.
Keywords
Petri Nets, Modeling, Reference Nets, Synchronous Channels, Socionics, Garbage Can Model of Organizational Choice.References
[Christensen and Hansen 92] S. Christensen and N. D. Hansen. Coloured Petri Nets Extended with Channels for Synchronous Communication. Technical Report DAIMI PB-390, Aarhus University.[CMO 72] M. D. Cohen, J. G. March, and J. P. Olsen. A Garbage Can Model of Organizational Choice. In: Administrative Science Quarterly, 17/1972, pages 1-25.
[Kummer 98] O. Kummer: Simulating Synchronous Channels and Net Instances. In: J. Desel, P. Kemper, E. Kindler, A. Oberweis (eds.): 5. Workshop Algorithmen und Werkzeuge für Petrinetze. Forschungsbericht Nr. 694, Fachbereich Informatik, Universität Dortmund, pages 73-78. Oktober 1998.
[Masuch and LaPotin 89] M. Masuch and P. LaPotin. Beyond Garbage Cans: An AI Model of Organizational Choice. In: Administrative Science Quarterly, March 1989, pages 38-67.
[Renew 99] O. Kummer and F. Wienberg. Renew- User Guide. URL: http://www.renew.de, Release 1.0, March 5, 1999.
