This paper shows a unified framework to examine data flow diagrams (DFD, for short) and Petri nets in modeling business processes. Many information systems methodologies use DFD's to depict business processes, which have discrete event nature. In order to provide a firm foundation for the comparison between a Petri net representation and the dynamic behavior of a business processes modeled by DFD, the concept of business transaction Petri nets is established. The behavior of a business transaction Petri net is simulated by the corresponding business transaction system.

The resulted framework makes it possible that the experiences with DFD's will be applied to Petri net models in modeling business processes, and vise versa. Especially, it is expected that the result will provide a basis of a novel design method for the dynamic performance of business processes.

The forms of business processes have been diversifying, though academic research of the processes in engineering discipline was not so developed enough as to guide them. Many business processes use feedback mechanisms through information systems as a control discipline. This paper investigates dynamic properties of such business processes with feedback information systems. The business transaction Petri nets (Sato, 1997c) are employed for that purpose. It will be turned out that periodic behavior comes out, depending on a parallel processing mechanism of business tasks and their processing capacity. A condition on which the cycle time of a business process and the maximal cycle mean of the corresponding Petri net coincides, will be determined.

Based on the result provided, a calculation method for the cycle time of a business process modeled by a data flow diagram will be devised. It uses the fact that the maximal cycle mean of a business transaction Petri net is nothing but the eigenvector of in transition matrix.

Even though the proposal of the standard of EDI protocol is expected to provide widely use of EDI, but there exist also the problem of initial cost, linkage among the EDI data, management information, and payment information. This paper deals with the analysis of EDI system in Japanese firms from the aspects of reuse of the EDI data as the management information, and the networking of firms through the ordering/receiving and the payment system. The study is based upon the questionaire for t he Japanese firms made by the authors. As a rsult, it is found that the the EDI data is mostly used as the management information, even though the initial cost of the EDI system is a kind of burden for firms. Almost all firms consider that the standardization of EDI protocol is the most important issues, but in the real transaction, they usually use the restricted (industry oriented) protocol or their own protocol. In term of the legal deregulation of financial transaction, almost all firms are expecting the advanced type of EDI such as the financial EDI. However, they are also seeking for the stability of payment system through he deposit retained in banks.

To enhance the efficiency of the face-to-face decision making meeting, this paper proposes an electronic support tool "ARRANGER" for communication prior to such meetings in asynchronous electronic communication. At first, we show the experimental asynchronous electronic communication analysis in order to understand the characteristics of this type of communication. According to this analysis, we find the following characteristic activities; (1) arrangement work concerning the meeting subject for discussion and the method of progress, and (2) activities that are requests, questions and its replies accompanying this work. In this situation, we propose a prototype system based on this analysis. The effectiveness of our proposal is demonstrated by our experiments.

In this study, we concern with a social dilemma of a virtual society. The virtual society is a kind of society in an information space that becomes possible to emerge due to a progress of information technology. In developing the society, it is necessary to include a mechanism to solve the social dilemma in an initial stage of its development. In order to propose a solution for the dilemma, we develop a model of the society. The model may provide us an operationality to deal with the problem. The results of simulation illustrate a possibility to solve the dilemma with respect to a size and complexity of the society. In the virtual society, the resolution of social dilemma may be easier than that in a society that requires a change of personal decision criteria. The operationality of the information space may give the advantage. Among the other findings, the society and its agents in the model reveal interesting behavior under a certain environmental condition. In conclusion, we may successfully develop the model of the society that reveals a collective behavior based on local rules of agents.