4 research outputs found
Updates in a Rule based Language for Objects
The integration of object-oriented concepts into deductive databases has been investigated for a certain time now. Various approaches to incorporate updates into deduction have been proposed. The current paper presents an approach which is based on object versioning; different versions of one object may be created and referenced during an update-process. By means of such versions it becomes possible to exert explicit control on the update process during bottom-up evaluation in a rather intuitive way. The units for updates are the result sets of base methods, i.e. methods, whose results are stored in the object-base and are not defined by rules. However, the update itself may be defined by rules. Update-programs have fixpoint semantics; the fixpoint can be computed by a bottom-up evaluation according to a certain stratification
MODELING DYNAMICS OF DATABASES WITH RELATIONAL DISCRETE EVENT SYSTEMS AND MODELS
Behavior of relational databases is studied within the framework of Relational Discrete Event
Systems (RDESes) and Models (RDEMs). Three behavior specification methods based on production
systems, recurrence equations, and Petri nets are defined and their expressive powers
are compared. Production system RDEM is extended to support non-determinism, and various
deterministic and non-deterministic production system interpreters are introduced and formally
compared in terms of their expressive power. It is shown that the parallel deterministic interpreter
has more expressive power than other interpreters including an OPS5-like interpreter.
Since it is also parallel, this makes the parallel deterministic interpreter a very attractive interpreter
for production systems.Information Systems Working Papers Serie