N. Bassiliades et I. Vlahavas, PROCESSING PRODUCTION RULES IN DEVICE, AN ACTIVE KNOWLEDGE-BASE SYSTEM, Data & knowledge engineering, 24(2), 1997, pp. 117-155
Citations number
44
Categorie Soggetti
Computer Sciences","Computer Science Artificial Intelligence","Computer Science Information Systems
Production rules are useful for several tasks in active database syste
ms, such as integrity constraint checking, derived data maintenance, d
atabase state monitoring, etc. Furthermore, production rules can expre
ss knowledge in a high-level form for problem solving in Knowledge Bas
e Systems (KBS). Present active object-oriented database (OODB) system
s traditionally provide event-driven rules which are triggered by even
ts, i.e. database modifications. This paper describes DEVICE, a high-l
evel rule integration scheme in an active OODB system, resulting in an
active KBS. The paper emphasises the run-time processing of productio
n rules, namely the incremental matching of rule conditions, as well a
s rule selection and firing. The matching of production rules requires
special algorithms based on the flow of updated data through a discri
mination network, like PETE, TREAT, etc. DEVICE offers a smooth integr
ation of production rules into an active OODB system that only support
s event-driven rules, without introducing new data structures, maintai
ning at the same time the properties of discrimination networks. This
is achieved using complex events to map the conditions of production r
ules and monitor the database to incrementally match those conditions.
DEVICE maps each production rule into one event-driven rule that is e
asy to maintain and offers centralised rule selection control for corr
ect run-time behaviour and conflict resolution. Furthermore, DEVICE pr
ovides the infrastructure for the integration of various other rule pa
radigms into a single KBS, like deductive rules and integrity constrai
nts and leaves room for the optimisation of the matching process throu
gh variations of the basic discrimination network.