: Based on Y. Shoham's paradigm, called Agent-Oriented Programming (AOP), multi-agentsystems are presented as a specialization of distributed, Object-Oriented systems. Equipped with knowledge, general concurrent inference mechanisms dealing with this knowledge, and a declarative agent program, these multi-agent-systems are intended to be a foundation of a new approach uniting advantages of many contributing areas: The precise semantics of Petri nets, the abstraction and encapsulation proposed in Object-Oriented approaches, and the power of logic programming, making it easy to adopt well-known AI-methods. As an example, an urban traffic information system will be designed which solves path searching problems in a distributed graph. Keywords: Multi-Agent-System, Agent-Oriented Programming, Distributed Artificial Intelligence, Distributed Object-Orientation, Coloured Petri Net. 1 Introduction In this paper, a representation of multi-agent-systems based on Coloured Petri nets will be int...

: The structure of High-level nets is studied from an algebraic and a logical point of view using Algebraic nets as an example. First the category of Algebraic nets is defined and the semantics given through an unfolding construction. Other kinds of Highlevel net formalisms are then presented. It is shown that nets given in these formalisms can be transformed into equivalent Algebraic nets. Then the semantics of nets in terms of universal constructions is discussed. A definition of Algebraic nets in terms of structured transition systems is proposed. The semantics of the Algebraic net is then given as a free completion of this structured transition system to a category. As an alternative also a sheaf semantics of nets is examined. Here the semantics of the net arises as a limit of a diagram of sheaves. Next Algebraic nets are characterized as encodings of special morphisms called foldings. Each algebraic net gives rise to a surjective morphism between Petri nets and conversely each sur...

Here we present a new module concept for place/transition nets that is based on the component concepts of Continuous Software Engineering (CSE). Place/transition net modules consist of three nets, import, body and export. The import net IMP states the prerequisites the modules assumes. The body net BOD represents the internal functionality. The export net EXP gives an abstraction of the body that can be used by the environment. The interfaces IMP and EXP are related to the body BOD via morphisms. The import net is mapped to the body BOD by a plain morphism. Plain morphisms map places onto places and transitions onto transition, while preserving the transitions pre- and postdomain. The export EXP is mapped to the body BOD by a substitution morphism. These morphisms map places to places as well. But transitions can be mapped to whole nets, i.e. to subnets of the target net. Substitution morphisms represent transition refinement and hence are adequate for relating export and body. We provide module operations to compose larger modules from basic ones. We have three different operations, composition, disjoint union, and union. Our main result is that these module operations are compatible with each other. We present a summary of our case study [PB01] to illustrate the given concepts.

Here we present a new module concept for Petri nets that is based on the component concepts of Continuous Software Engineering (CSE). According to that concept two distinguished interfaces are required. These are import and export interfaces. The import describes the assumptions on the environment, e.g. in terms of used components. The export gives an abstraction of the functionality and presents e.g. the offered services. The modules for

Component-based software engineering needs to be backed by thorough formal concepts and modeling techniques. This paper combines two concepts introduced independently by the two authors in previous papers. On one hand, the concept of Petri net modules introduced at IDPT 2002 in Padberg (2002b), and on the other hand a generic component framework for system modeling introduced at FASE 2002 in Ehrig et al. (2002). First we develop a categorical formalization of the transformation based approach to components that is based on pushouts. This is the frame in which we show that Petri net modules can be considered as an instantiation of the generic component framework. This allows applying the transformation based semantics and compositionality result of the generic framework to Petri net modules. In addition to general Petri net modules we introduce Petri net modules preserving safety properties which can be considered as another instantiation of pushout based formalization of the generic framework.