[Reaction-tg] Reaction TG weekly call - agenda

[Wagner, G.R.]

What is not a reaction rule?
Since essentially everything that happens in a rule-based system may be viewed as ultimately driven by events, could every rule be cast as a reaction rule?  The answer is: no! Other types of rules, such as derivation rules and transformation rules, do not refer to events, and their semantics abstracts away from any time and event aspects. Therefore, it is a different story, that when such rules are being executed, certain processing events are part of the execution procedure – these events are not relevant, semantically.
However, there is one type of rule that seems to be pretty close to reaction rules: production rules.  

Why is a production rule not a reaction rule?
Production rules produce an action whenever a state condition is satisfied through an update of the underlying knowledge base state. But unlike database triggers, which are reaction rules, production rules do not specify these update events explicitly. Therefore, in RuleML, production rules are considered to be a separate rule concept, not being subsumed under reaction rules.

Reaction rules will, in practice, be working in concert with other types of rules and the different types of rules must fit into one common view of a rule-based system.