Relaxing and Restraining Queries for OBDA

  • Medina Andreşel TU Wien
  • Yazmín Ibáñez-García TU WIEN
  • Magdalena Ortiz TU Wien, Austria
  • Mantas Šimkus TU Vienna


We advocate the use of ontologies for relaxing and restraining queries, so that they retrieve either more or less answers, enabling the exploration of a given dataset. We propose a set of rewriting rules to relax and restrain conjunctive queries (CQs) over datasets mediated by an ontology written in a dialect of DL-Lite with complex role inclusions (CRIs). The addition of CRI enables the representation of knowledge about data involving ordered hierarchies of categories, in the style of multi-dimensional data models. Although CRIs in general destroy the first-order rewritability of CQs, we identify settings in which CQs remain rewritable.

AAAI Technical Track: Knowledge Representation and Reasoning