Overview
Graal is dedicated to ontology-mediated query answering. This task consists of computing the answers to a (conjunctive) query over a knowledge base composed of facts (data) and an ontology, given as a set of existential rules.
Graal is composed of eight modules:
- Core: implements the fundamental classes such as Atom, AtomSet, Rule, ConjunctiveQuery …;
- IO: provides readers from or writers to textual formats;
- Store: allows access to different kinds of storage systems;
- Homomorphism: implements algorithms to query data;
- Forward Chaining: implements forward chaining (aka chase) algorithms;
- Backward Chaining: implements query rewriting algorithms;
- Rule Set Analyser: provides tools to analyse structural properties of a rule set;
- KB: provides a Knowledge Base layer using previous modules to answer queries.
