原田 良雄

This paper proposes a method of supporting behavioral decision-making with a rule-based system to be used for the design stage of service specifications or service scenarios based on a state transition model. We consider telecommunication services as service scenarios of state transitions. A state transition can be described as a transition rule that is represented as the notation of an IF-THEN rule : "if < condition > then < action >." Thus, behaviors or service scenarios are assumed to be treated as a set of IF-THEN rules in this paper. In general, an "if < condition > then < action >" rule is called a production rule, and production rules are often used to represent knowledge in expert systems. Thus, rules treated in this paper are a kind of production rule. It is still difficult to decide if behaviors are concurrent, cooperative, or exclusive as a whole system when many service scenarios are combined, even if each rule is clearly described and easy to understand. When several service scenarios are combined, it is necessary for the sub-elements of each state transition to cooperate. The method proposed in this paper consists of the following techniques: (1) decompositions of a state transition to sub-elements, (2) rule descriptions for the decomposed sub-elements and the application of rules, (3) use of conflict and cooperation strategies, and (4) support for behavioral decision-making by showing recommendations for cooperative, exclusive, or concurrent behavior. We provide examples of telecommunication services to show the effectiveness of the proposed method in an easy-to-understand manner. We also show cooperative resolution in the interactions among several services.

In general, when many functions and services are added to a system, verification and validation become difficult. In design and development in telecommunication services, conflicts that arise from combined telecommunication services have been discussed from various viewpoints. However, correctly and efficiently detecting all conflicts is still not possible and the resolution of conflicts primarily depends on expert designers, who are finding that these problems are beyond their ability. Thus, the burden on the designer must also be alleviated at the design stage. Service interference, which is discussed in this paper, is a kind of conflict. A problem of service interference is that during service, other services interfere with the ongoing service behavior. That is to say, a strange state arises, or an input event doesn't work, or a strange transition occurs, etc. The detection of service interference by only comparing states among services is nor enough since the state transition must be considered in the service interference. This paper proposes how to automatically detect the service interference with a rule-based system and an extended adjacency matrix. The proposed method uses and combines features of both the adjacency matrix and rule-based system. The method first generates the extended adjacency matrix by the rule application, then extracts sequences of the state, the event, and the rule applications, and then detects the service interference with the extracted sequences.

The detection and elimination of telecommunication service interactions are still urgent problems. Conflict, which is discussed in this paper, is one of the problems that comes under heading of telecommunication service interactions. The main problem in detecting conflict is due to the difficulty of grasping and predicting states when services are combined. This paper describes a method of automatically acquiring these states. Telecommunication service behaviors are assumed to be described as a set of rules. When acquiring the states by applying rules, it is necessary to know whether an arbitrary terminal stare is synchronized with the other terminal states. Although determining synchronization among multiple terminal stares is ordinarily difficult for the designer, by using the proposed method, states can be automatically generated without the designer's intervention.

A conflict detection support method for combining additional telecommunication services with existing services is proposed. In this method, telecommunication services are described by the STR (State Transition Rule) method which specifies a set of state transition rules. Though conflict detection in the past depended on manual analysis by the designer, with this method, conflict candidates are mechanically narrowed down and indicated to the designer. All conflicts between five actual telecommunication service descriptions are detected in an experiment using a system developed in line with the proposed method.