Abstract
The retrieval problem is one of the main reasoning problems for ontology based systems. Retrieval problem for concept C consists in finding all individuals a which satisfy C(a).
We present ontology transformation which can help to improve evaluating queries over ontologies expressed in a subset of OWL. Our solution is based on translating retrieval concepts into relational algebra expressions and consequently to SQL queries over a database constructed from the original ontology.
Ontology transformation into database is ontology-dependent but fully automatic and it is provided by system TORQue.