_Sequential. This class implements a simple counter. It does not define a state-transition from state b1 and state b0 as this would prevent any subclass from implementing a larger counter. Figure 5 extends the counter to count to 4. It is a subclass of Counter_2 and has been enhanced with the addition of two states (b2, b3) and 3 state-transitions. The states and transitions inherited from the class Counter_2 are shown as being shaded. The state-transition from state b3 to state b0 produces an event named `cnt4'. This event is broadcast throughout the state machine and in addition is made available through the external event interface from where it can be used by other parts of a model, possibly modelled using different formalisms. Class Counter_4 reuses the states and state-transitions defined in class Counter_2. Finally, in figure 6 the class Counter_8 is shown to consist of two embedded components of class Counter_4, one of which is marked as the initial state. As the two compo...

As the size of a formal model increases, state space analysis becomes more complex in terms of time or space or both. This complexity means that state space analysis of a formal model is often practically impossible, even for a modest sized system. Recently techniques to reduce the complexity have done so by taking advantage of the structure built into the model by the designer (e.g. [16]). In a similar vein we plan to take advantage of the incremental specification that is found in many formal models. This paper examines a number of case studies to determine the various types of incremental change that are used in practice and presents a sketch of an incremental state space generation algorithm. 1 Introduction One of the major benefits of developing a formal model is that it can be analysed. The ultimate goal of analysing a model is to show that the system will work correctly, or to find out why it will not work in order to make appropriate modifications. A formal model is analysed f...

. This article provides an overall view of available techniques for integrating Petri-nets and object-oriented concepts. In order to outline specific characteristics, all identified techniques will be grouped into three categories. For each of these categories, one representative technique will be selected as well as demonstrated using the example of a simple logistics system. The focus is not an in-depth evaluation but rather a preassessment of potential benefits for developing corporate information systems. 1 Introduction Petri-nets are a powerful instrument for modeling, analyzing, and simulating dynamic systems with concurrent and non-deterministic behavior. They are often criticized because their application for real-world problems leads to incomprehensible and complex net models. Furthermore, they are considered an isolated method that lacks integration with other existing modeling techniques [Balz96, 319; Zele95, 72]. Techniques for object-oriented analysis and design pr...