Prof.dr. Dorel LUCANU
Universitatea Alexandru Ioan Cuza, Facultatea de Informatica
Iasi
Romania
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Logic Programming Views on Web Ontologies
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ABSTRACT
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In the recent years, we have seen a great increase of the number
of ontology languages in the Semantic Web domain. Languages
of the description logics (DL) origin, such as DAML+OIL and
OWL have been widely accepted as the de-facto ontology language
for the Semantic Web. However, OWL has been criticized for a
number of drawbacks, such as the unnaturalness of the modeling,
the treatment of constraints vs restrictions, the inappropriate
layering on top of RDF Schema, the inefficiency of query answering
support, etc. It is for this reason that the OWL— suite of languages,
a strict subset of OWL, was proposed. OWL— contains three sub
languages, OWL Lite—, OWL DL— and OWL Full—, which are the subsets
of OWL Lite, DL and Full, respectively. OWL— is based on Description
Logic Programs hence it taps advantages from the logic programming
paradigm. Institutions and institution morphisms were developed
to reason about software systems without assumption of the underlying
logical systems. In this paper, we use institution (co)morphisms
to investigate the relationship between OWL DL—, the LP variant
of OWL DL, with some formalisms relevant to the Semantic Web
community.
We start from an institution independent definition of Logic
Programming (LP) and define three views also formalized as institutions:
LP satisfying OWA, LP satisfying CWA, and LP with knowledge
bases. The three views are then applied to web ontology languages.
Since OWL DL— is the largest subset of OWL which can be translated
in First Order Horn Logic, we focus on this language. The first
main advantage is that we can use Herbrand Theorem for institution
independent logic programming to show that initial models can
be used for proving positive queries in the case of OWA view.
In other words, Herbrand Theorem says that OWA view and CWA
view are equivalent over positive queries provided the initial
model exists. We show that OWL DL— has initial models which
coincide with the initial models of the First Order Horn Logic
translations. The second main advantage is that the same web
ontology can be investigated from different viewpoints. For
each view, we may borrow an existent reasoner for the corresponding
LP. In this way, we provide a theoretical foundation for multiparadigm
based reasoners for web ontologies. Moreover, we show that the
institution independent Horn Logic can be used to add Horn rules
to each of web ontology language. For OWL DL— with Horn rules,
we still have First Order Horn Logic semantics and datalog semantics,
respectively
          
SHORT CV
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Dr. Dorel Lucanu is a Professor in the 
Faculty of Computer Science, 
"A.I.Cuza" University of Iasi, Romania. 
He received his MS in  Mathematics and 
Computer Science from the same University in 1981, 
and his PhD in Computer Science from the Institute of Mathematics,
Romanian Academy in 1994.
His interest fields include rewriting logic, 
specification and verification of concurrent objects, 
and formal methods in semantic web.