Reaction Rules

Abstract

There are several types of rules playing an important role in knowledge and information processing systems. The most important ones are reaction and deduction rules. As opposed to simple database systems where the only reasoning service is query answering, more advanced systems offer in addition a number of advanced reasoning services such as deductive query answering by means of deduction rules, reactive input processing by means of reaction rules, and the abductive generation of explanations, diagnoses and plans (based on the ability to represent actions). In this chapter, we discuss the concept of reaction rules subsuming production rules and database triggers as special cases. We describe a simple model of communication events and show how the communicative behavior of a database can be specified with the help of reaction rules referring to incoming messages representing communication events. Finally, the communication between the member databases of a multidatabase system is discussed as a natural example for the application of reaction rules.