Temporal Query Answering in Lightweight Description Logics | (Statusvortrag)

Date

Nov 16, 2015

Time

3:30 PM - 4:30 PM

Speaker

Veronika Thost

Language

en

Main Topic

Informatik

Other Topics

Informatik

Description

Ontology-based query answering (OBQA) augments classical query answering over data bases: by adopting the open-world assumption, information not present in the data is considered to be unknown rather than false; moreover, the domain knowledge provided by an ontology is taken into account. By describing a common domain terminology, ontologies also support the integration of data coming from heterogeneous sources. Many applications of OBQA use ontologies formulated in so-called lightweight Description Logics (DLs), which guarantee efficient reasoning in terms of computational complexity. Recently, the OBQA scenario has been extended to incorporate the often temporal nature of data - such that the query language, the ontology language, or both allow to address different points in time explicitly. However, if temporal operators are allowed in the ontology, reasoning gets very complex or even undecidable even for lightweight DLs. Temporal query answering w.r.t. traditional, atemporal DL ontologies has, so far, only been studied regarding very expressive Description Logics as ontology languages. The complexity of the problem is still unknown w.r.t. lightweight DLs. We investigate the usefulness of temporal OBQA for applications dealing with large amounts of data and requiring low reasoning complexities. To this end, we focus on (atemporal) ontologies in lightweight DLs and study the complexity of the temporal query entailment problem. In the talk, we regard various lightweight DLs and the recently proposed query language of temporal conjunctive queries. We then describe why the algorithms proposed for expressive DLs are not directly applicable and show how this can be resolved. We conclude the talk by outlining further research questions and interesting results of our work. Betreuer: Prof. Dr.-Ing. Franz Baader Fachreferent: Prof. Dr. rer. nat. habil. Uwe Aßmann

Last modified: Nov 16, 2015, 8:59:00 AM