Efficient Query Answering over Ontologies

Title: Efficient Query Answering over Ontologies
Speaker: Dr. Jeff Z. Pan (University of Aberdeen, UK)
Time: 3:00pm, Monday，Apirl 21
Venue: Lecture room, Lab for Computer Science, Level 3 Building #5, Institute of Software, CAS

Abstract: Efficient query answering over ontologies is one of the most useful and important services to support Semantic Web applications. Approximation has been identified as a potential way to reduce the complexity of query answering over OWL DL ontologies. Existing approaches are mainly based on syntactic approximation of ontological axioms and queries. In this talk, I will propose to recast the idea of knowledge compilation into
semantically approximating OWL DL ontologies with DL-Lite ontologies, against which query answering has only polynomial data complexity. We identify a useful category of queries for which our approach guarantees also completeness. Furthermore, I will also report on the implementation of our approach in the ONTOSEARCH2 system and preliminary, but encouraging, benchmark results which compare ONTOSEARCH2’s response times on a number of queries with those of existing ontology reasoning systems.

Bio. :
Dr. Jeff Z. Pan received the PhD degree in computer science from The University of Manchester in 2004, advised by Prof. Ian Horrocks on the topic of Description Logics reasoning support for the Semantic Web. He has been a Lecturer of Computing Science at the University of Aberdeen, UK, since 2005. His current research
focuses primarily on the design of logics and ontology languages, automated reasoning, ontology reuse and usability, as well as the applications (such as in the Semantic Web, multimedia and software engineering) of all the above. Over the years, Dr. Pan has contributed to several high-profile projects, such as the highly prestigious, EPSRC-funded Interdisciplinary Research Collaboration on Advanced Knowledge Technologies (AKT) and the European Commission FET project Wonder Web, which effectively contributed to the creation of the W3C OWL Web Ontology Language. He has also led The Aberdeen University’s contribution to several EU-funded and national projects, such as the European Commission Network of Excellent Knowledge Web project and the STREP MOST project..

Dr. Pan is an Associate Editor of the Journal of Advances in Artificial Intelligence and on the Editorial Board of
International Journal on Semantic Web and Information Systems (IJSWIS). He served as a guest editor of special issues of international journals, such as the Journal of Logic and Computation and the Journal of Data Semantics. He is a PC Chair of the first ever Semantic Web reasoning conference – The First International Conference on Web Reasoning and Rule Systems (RR2007). Dr. Pan has published widely in leading journals and conferences related to ontology and the Semantic Web. He co-edited a number of W3C technical reports, such as “XML Schema Datatypes in RDF and OWL”. He chairs the OWL Task Force on Uncertainty and the Fuzzy RuleML Technical Group.