Modelling the Future with Event Choice DATALOG.
Antonella Guzzo, Domenico Saccà · 2002
This paper presents a rule-based declarative database language which extends stratified DATALOG to express events and nondeterministic state transitions, by using various types of choice to model uncertainty in dynamic rules. The proposed language, called Event Choice DATALOG (DATALOG for short), is particularly suitable to formulate queries on the evolution of a knowledge base on the basis of a given sequence of events that are envisioned to occur in the future. The semantics of a DATALOG program is given by means of rule rewriting which transforms it into a DATALOG program with choice and a particular form of XY-stratification, called XYZ-stratification, that uses a pair of temporal arguments to handle evolution.