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


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.