# Answering conjunctive queries in the SHIQ description logic

##### Birte GlimmBirte Glimm,  Carsten LutzCarsten Lutz,  Ian HorrocksIan Horrocks,  Ulrike SattlerUlrike Sattler
Birte Glimm, Carsten Lutz, Ian Horrocks, Ulrike Sattler
Answering conjunctive queries in the SHIQ description logic
Journal of Artificial Intelligence Research, 31:150-197, 2008
• KurzfassungAbstract
Conjunctive queries play an important role as an expressive query language for Description Logics (DLs). Although modern DLs usually provide for transitive roles, conjunctive query answering over DL knowledge bases is only poorly understood if transitive roles are admitted in the query. In this paper, we consider unions of conjunctive queries over knowledge bases formulated in the prominent DL SHIQ and allow transitive roles in both the query and the knowledge base. We show decidability of query answering in this setting and establish two tight complexity bounds: regarding combined complexity, we prove that there is a deterministic algorithm for query answering that needs time single exponential in the size of the KB and double exponential in the size of the query, which is optimal. Regarding data complexity, we prove containment in co-NP.
• Forschungsgruppe:Research Group: Automatentheorie
@article{ GliHoLuSa-JAIR08,
author = {Birte {Glimm} and Carsten {Lutz} and Ian {Horrocks} and Ulrike {Sattler}},
journal = {Journal of Artificial Intelligence Research},
pages = {150--197},
title = {Answering conjunctive queries in the $\mathcal{SHIQ}$ description logic},
volume = {31},
year = {2008},
}