# 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
In Manuela Veloso, eds., Proceedings of the Twentieth International Joint Conference on Artificial Intelligence (IJCAI'07), 299-404, 2007. AAAI Press
• KurzfassungAbstract
Conjunctive queries play an important role as an expressive query language for Description Logics (DLs). Although modern DLs usually provide for transitive roles, it was an open problem whether conjunctive query answering over DL knowledge bases is decidable if transitive roles are admitted in the query. In this paper, we consider conjunctive queries over knowledge bases formulated in the popular DL SHIQ and allow transitive roles in both the query and the knowledge base. We show that query answering is decidable and establish the following complexity bounds: regarding combined complexity, we devise 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. Regarding data complexity, we prove co-NP-completeness.
• Forschungsgruppe:Research Group: Automatentheorie
@inproceedings{ GliHoLuSa-07,
author = {Birte {Glimm} and Carsten {Lutz} and Ian {Horrocks} and Ulrike {Sattler}},
booktitle = {Proceedings of the Twentieth International Joint Conference on Artificial Intelligence (IJCAI'07)},
editor = {Manuela {Veloso}},
pages = {299--404},
publisher = {AAAI Press},
title = {Answering conjunctive queries in the $\mathcal{SHIQ}$ description logic},
year = {2007},
}