references-jos.bib

@inproceedings{debruijn-rezk-2009,
  author = {Jos de Bruijn and
               Mart\'{\i}n Rezk},
  title = {A Logic Based Approach to the Static Analysis of Production
               Systems},
  booktitle = {3rd International Conference on Web Reasoning and Rule Systems (RR 2009)},
  address = {Chantilly, VA, USA},
  year = {2009},
  pages = {254--268},
  url = {http://www.debruijn.net/publications/logicPS-camera-ready.pdf},
  abstract = {In this paper we present an embedding of propositional
production systems into $\mu$-calculus, and first-order
production systems into fixed-point logic, with the aim of
using these logics for the static analysis of production
systems with varying working memories.  We  encode properties
such as termination and confluence in these logics, and briefly
discuss which ones cannot
be expressed, depending on the expressivity of the logic. We show
how the embeddings can be used for reasoning over the
production system, and use known results to obtain
upper bounds for special cases. The strong correspondence
between the structure of the models of the encodings and the
runs of the production systems enables the straightforward
modeling of properties of the system in
the logic.}
}
@inproceedings{Bruijn-Heymans-CompStabModeSema-09,
  bibsection = {CONF},
  author = {Jos de Bruijn and Stijn Heymans},
  title = {Complexity of the Stable Model Semantics for Queries on Incomplete Databases},
  booktitle = {Proceedings of the 10th International Conference on Logic Programming and Nonmonotonic Reasoning  (LPNMR2009)},
  address = {Potsdam, Germany},
  month = {September 14--18},
  year = {2009},
  url = {http://www.debruijn.net/publications/incomplete_db.pdf},
  abstract = {We study the complexity of consistency checking and query answering on incomplete databases for languages ranging from
non-recur\-sive Datalog to disjunctive Datalog with negation under the stable model semantics. We consider both possible and
certain answers and both closed- and open-world interpretation
of \emph{C-databases} with and without conditions. By reduction
to stable models of logic programs we find that, under
closed-world interpretation, adding negation to (disjunctive)
Datalog does not increase the complexity of the considered
problems for C-databases, but certain answers for databases
without conditions are easier for Datalog without than with
negation. Under open-world interpretation, adding negation to
non-recursive Datalog already leads to undecidability, but the
complexity of certain answers for negation-free queries is the
same as under closed-world interpretation.}
}
@inproceedings{Seylan-EffeQuerRewrwith-09,
  bibsection = {CONF},
  author = {\.Inan\c{c} Seylan and Enrico Franconi and Jos de Bruijn},
  title = {Effective Query Rewriting with Ontologies over DBoxes},
  booktitle = {Proceedings of the 21st International Joint Conference on Artificial Intelligence (IJCAI2009)},
  address = {Pasadena, CA, USA},
  month = {July 11--17},
  year = {2009},
  url = {http://www.debruijn.net/publications/macbee-final-ijcai-09.pdf},
  abstract = {We consider query answering on Description Logic (DL) ontologies
                  with DBoxes, where a DBox is a set of assertions on individuals
                  involving atomic concepts and roles called DBox predicates. The
                  extension of a DBox predicate is exactly defined in every
                  interpretation by the contents of the DBox, i.e., a DBox faithfully
                  represents a database whose table names are the DBox predicates and
                  the tuples are the DBox assertions. Our goals are (i) to find out
                  whether the answers to a given query are solely determined by the
                  DBox predicates and, if so, (ii) to find a rewriting of the query in
                  terms of them. The resulting query can then be efficiently evaluated
                  using standard database technology. We have that (i) can be reduced
                  to entailment checking and (ii) can be reduced to finding an
                  interpolant. We present a procedure for computing interpolants in
                  the DL $\mathcal{ALC}$ with general TBoxes. We extend the procedure with
                  standard tableau optimisations, and we discuss abduction as a
                  technique for amending ontologies to gain definability of queries of
                  interest.}
}
@inproceedings{Bruijn-EiterETAL-EmbeApprCombRule-08,
  bibsection = {CONF},
  author = {Bruijn, Jos de and Thomas Eiter and
                  Hans Tompits},
  title = {Embedding Approaches to Combining Rules and Ontologies into
Autoepistemic Logic},
  booktitle = {Proceedings of the 11th International Conference on Principles of Knowledge Representation and Reasoning (KR2008)},
  year = {2008},
  address = {Sydney, Australia},
  month = {September 16--19},
  pages = {485--495},
  url = {http://www.debruijn.net/publications/embedding-approaches-kr-08.pdf},
  abstract = {The combination of rules and ontologies
                  has a central role in the ongoing development of the Semantic Web.
                  In previous work, \emph{autoepistemic logic} (AEL) was
advocated as a uniform host formalism to study different such
combinations, enabling comparisons  on a common basis. In this
paper, we continue this line of research and investigate
different embeddings of major proposals to combine rules and
ontologies into first-order autoepistemic logic (FO-AEL). In
particular, we present embeddings for dl-programs, r-hybrid
knowledge bases, and hybrid MKNF knowledge bases, which are
representatives of different combination types. We study the
embeddings in the context of FO-AEL under the standard-names
assumption, but we also discuss variants using the any- and
all-names semantics. Our results provide interesting insights
into the properties of the discussed combination formalisms.}
}
@inproceedings{Bruijn-PearceETAL-QuanEquiLogiHybr-07,
  bibsection = {CONF},
  author = {Bruijn, Jos de and David Pearce and Axel Polleres and Agust{\'i}n Valverde},
  title = {Quantified Equilibrium Logic and Hybrid Rules},
  booktitle = {Proceedings of the 1st International Conference on Web Reasoning and Rule Systems (RR2007)},
  year = {2007},
  address = {Innsbruck, Austria},
  month = {June 7--8},
  pages = {58--72},
  publisher = {Springer},
  abstract = {In the ongoing discussion about combining rules and Ontologies on the Semantic Web
a recurring issue is how to combine first-order classical logic with
nonmonotonic rule languages. Whereas several modular approaches to
define a combined semantics for such hybrid knowledge bases focus
mainly on decidability issues, we tackle the matter from a more
general point of view. In this paper we show how Quantified
Equilibrium Logic (QEL) can function as a unified framework which
embraces classical logic as well as disjunctive logic programs under
the (open) answer set semantics. In the proposed variant of QEL  we
relax the unique names assumption, which was present in earlier
versions of QEL. Moreover, we show that this framework elegantly
captures the existing modular approaches for hybrid knowledge bases
in a unified way.},
  url = {http://www.debruijn.net/publications/rr2007-qel.pdf}
}
@inproceedings{Bruijn-Heymans-LogiFoun-07,
  bibsection = {CONF},
  author = {Bruijn, Jos de and Stijn Heymans},
  title = {Logical Foundations of (e){RDF(S)}: Complexity and
Reasoning},
  booktitle = {Proceedings of the 6th International Semantic Web Conference and 2nd Asian Semantic Web Conference (ISWC2007+ASWC2007)},
  year = {2007},
  series = {Lecture Notes in Computer Science},
  pages = {86--99},
  number = {4825},
  address = {Busan, Korea},
  month = {November},
  publisher = {Springer},
  abstract = {An important open question in the semantic Web is the precise
relationship between the RDF(S) semantics and the semantics of
standard knowledge representation formalisms such as logic
programming and description logics. In this paper we address this
issue by considering embeddings of RDF and RDFS in
logic. Using these embeddings, combined with existing results
about various fragments of logic, we establish several novel
complexity results. The embeddings we
consider show how techniques from deductive databases and
description logics can be used for reasoning with RDF(S). Finally, we
consider querying RDF graphs and establish the data complexity of
conjunctive querying for the various RDF entailment regimes.
.},
  url = {http://www.debruijn.net/publications/frames-rdf-conference.pdf}
}
@inproceedings{Bruijn-Heymans-RDF-Logi-07,
  bibsection = {CONF},
  author = {Bruijn, Jos de and Stijn Heymans},
  title = {{RDF} and Logic: Reasoning and Extension},
  booktitle = {Proceedings of the 6th International Workshop on Web Semantics (WebS 2007), in conjunction with the 18th International Conference on Database and Expert Systems Applications (DEXA 2007)},
  year = {2007},
  address = {Regensburg, Germany},
  month = {September 3--7},
  publisher = {IEEE Computer Society Press},
  abstract = {In this paper, we explore embeddings of the various kinds of RDF
                  entailment in F-Logic.  We show that the embeddings of simple, RDF,
                  and RDFS entailment, as well as a large fragment of extensional
                  RDFS entailment, fall in the Datalog fragment of F-Logic, allowing
                  the use of optimization techniques from the area of deductive
                  databases for reasoning with RDF.  Using earlier results on the
                  relationship between F-Logic and Description Logics (DLs), we define an embedding of a
                  large fragment of extensional RDFS in a tractable description logic,
                  namely DL-Lite, allowing efficient reasoning over the ontology
                  vocabulary. We show how, using these embeddings, RDFS can be extended with rules and/or general axioms.},
  url = {http://www.debruijn.net/publications/frames-rdf-workshop.pdf}
}
@inproceedings{Bruijn-Heymans-SemaFramLangLaye-07,
  bibsection = {CONF},
  author = {Bruijn, Jos de and Stijn Heymans},
  title = {A Semantic Framework for Language Layering in {WSML}},
  booktitle = {Proceedings of the 1st International Conference on Web Reasoning and Rule Systems (RR2007)},
  year = {2007},
  address = {Innsbruck, Austria},
  month = {June 7--8},
  pages = {103--117},
  publisher = {Springer},
  abstract = {WSML presents a framework encompassing different language variants,
rooted in Description Logics and (F-)Logic Programming. So far, the
precise relationships between these variants have not been
investigated. We take the nonmonotonic \emph{first-order
autoepistemic logic}, which generalizes both Description Logics and
Logic Programming, and extend it with frames and concrete domains,
to capture all features of WSML; we call this novel formalism
FF-AEL. We consider two forms of language layering for WSML, namely
\emph{loose} and \emph{strict} layering, where the latter enforces
additional restrictions on the use of certain language constructs in
the rule-based language variants, in order to give additional
guarantees about the layering. Finally, we demonstrate that each
WSML variant semantically corresponds to its target formalism,
i.e.~WSML-DL corresponds to $\mathcal{SHIQ}(\mathbf{D})$, WSML-Rule to the Stable Model
Semantics for Logic Programs, a generalization of the Well-Founded
Semantics, and WSML-Core to $\mathcal{DHL}(\mathbf{D})$ (without nominals), the Horn
subset of $\mathcal{SHIQ}(\mathbf{D})$.},
  url = {http://www.debruijn.net/publications/rr2007-wsml.pdf}
}
@inproceedings{bruijn07-embed-non-groun-logic-progr,
  bibsection = {CONF},
  author = {Bruijn, Jos de and Thomas Eiter and Axel Polleres and
                  Hans Tompits},
  title = {Embedding Non-Ground Logic Programs into Autoepistemic Logic
                  for Knowledge-Base Combination},
  booktitle = {Proceedings of the 20th International Joint Conference on Artificial Intelligence (IJCAI2007)},
  year = {2007},
  address = {Hyderabad, India},
  month = {January 6--12},
  publisher = {AAAI Press},
  url = {http://www.debruijn.net/publications/fo-ael-ijcai07.pdf},
  abstract = {  In the context of the Semantic Web, several approaches to the
                  combination of ontologies, given in terms of theories of classical first-order logic, and rule
                  bases have been proposed. They either cast rules into classical
                  logic or limit the interaction between rules and ontologies. Autoepistemic
                  logic (AEL) is an attractive formalism which allows to
                  overcome these limitations, by serving as a uniform host language to embed ontologies and nonmonotonic
                  logic programs into it. For the latter, so far only the
                  propositional setting has been considered.
                  In this paper, we present several embeddings
                  of normal and disjunctive non-ground logic programs under the stable-model semantics into first-order
                  AEL, and compare them in combination with classical theories, with respect to
                  stable expansions and autoepistemic consequences. Our results reveal
                  differences and correspondences of the embeddings and provide a
                  useful guidance in the choice of a particular embedding for knowledge combination.}
}
@inproceedings{Hepp-Bruijn-GenT-07,
  bibsection = {CONF},
  author = {Martin Hepp and Bruijn, Jos de},
  title = {{GenTax}: A Generic Methodology for Deriving {OWL} and {RDF-S} Ontologies from Hierarchical Classifications, Thesauri, and Inconsistent Taxonomies},
  booktitle = {Proceedings of the 4th European Semantic Web Conference (ESWC2007)},
  pages = {129--144},
  year = {2007},
  number = {4519},
  series = {Lecture Notes in Computer Science},
  address = {Innsbruck, Austria},
  month = {June},
  publisher = {Springer},
  url = {http://www.debruijn.net/publications/hepp-eswc2007.pdf},
  abstract = {Hierarchical classifications, thesauri, and informal taxonomies are
likely the most valuable input for creating, at reasonable cost, non-toy
ontologies in many domains. They contain, readily available, a wealth of
category definitions plus a hierarchy, and they reflect some degree of
community consensus. However, their transformation into useful ontologies is
not as straightforward as it appears. In this paper, we show that (1) it often
depends on the context of usage whether an informal hierarchical categorization
schema is a classification, a thesaurus, or a taxonomy, and (2) present a novel
methodology for automatically deriving consistent RDF-S and OWL ontologies
from such schemas. Finally, we (3) demonstrate the usefulness of this approach
by transforming the two e-business categorization standards eCl@ss and
UNSPSC into ontologies that overcome the limitations of earlier prototypes.
Our approach allows for the script-based creation of meaningful ontology
classes for a particular context while preserving the original hierarchy, even if
the latter is not a real subsumption hierarchy in this particular context. Human
intervention in the transformation is limited to checking some conceptual
properties and identifying frequent anomalies, and the only input required is an
informal categorization plus a notion of the target context. In particular, the
approach does not require instance data, as ontology learning approaches would
usually do.}
}
@inproceedings{bruijn-et-al-06,
  bibsection = {CONF},
  author = {Bruijn, Jos de and David Pearce and Axel Polleres and Agust{\'i}n Valverde},
  title = {A Logic for Hybrid Rules},
  booktitle = {Proceedings of the Ontology and Rule Integration Workshop at the 2nd International Conference on Rules and Rule Markup Languages for the Semantic Web},
  year = {2006},
  address = {Athens, Georgia, USA},
  month = {November 11},
  url = {http://www.debruijn.net/publications/rule-integ.pdf},
  abstract = {
In the ongoing discussion about rule extensions for Ontology languages on the Semantic Web
a recurring issue is how to combine first-order classical logic with nonmonotonic rule languages.
Whereas several modular approaches to define a combined semantics for such hybrid knowledge bases
focus mainly on decidability issues, we tackle the matter from a more general point of view.
In this paper we show how Quantified Equilibrium Logic (QEL) can function as a unified
framework that embraces classical logic as well as disjunctive logic programs under the
(open) answer set semantics. In the proposed variant of QEL  we relax the unique names
assumption from earlier versions. Moreover, we show that this framework elegantly captures
several modular approaches to nonmonotonic semantics for hybrid knowledge bases.}
}
@inproceedings{bruijn06-web-servic-model-languag,
  bibsection = {CONF},
  author = {Bruijn, Jos de and Holger Lausen and Axel Polleres
                  and Dieter Fensel},
  title = {The Web Service Modeling Language: An Overview},
  booktitle = {Proceedings of the 3rd European Semantic Web Conference (ESWC2006)},
  pages = {590--604},
  year = {2006},
  number = {4011},
  series = {Lecture Notes in Computer Science},
  address = {Budva, Montenegro},
  month = {June},
  publisher = {Springer},
  url = {http://www.debruijn.net/publications/wsml-eswc2006.pdf},
  abstract = {The Web Service Modeling Language (WSML) is a
                  language for the specification of different aspects
                  of Semantic Web Services. It provides a formal
                  language for the Web Service Modeling Ontology WSMO
                  which is based on well-known logical formalisms,
                  specifying one coherent language framework for the
                  description of Semantic Web Services, start- ing
                  from the intersection of Datalog and the Description
                  Logic $\mathcal{SHIQ}$. This core language is
                  extended in the directions of Description Logics and
                  Logic Programming in a principled manner with strict
                  layering. WSML distinguishes between conceptual and
                  logical modeling in order to facilitate users who
                  are not familiar with formal logic, while not
                  restricting the expressive power of the language for
                  the expert user. IRIs play a central role in WSML as
                  identifiers. Furthermore, WSML defines XML and RDF
                  serializations for inter-operation over the Semantic
                  Web. }
}
@inproceedings{bruijn06-trans-ontol-from-predic-based,
  bibsection = {CONF},
  author = {Bruijn, Jos de and Stijn Heymans},
  title = {Translating Ontologies from Predicate-based to
                  Frame-based Languages},
  booktitle = {Proceedings of the 2nd International Conference on Rules and Rule Markup Languages for the Semantic Web (RuleML2006)},
  year = {2006},
  address = {Athens, Georgia, USA},
  month = {November 10-11},
  publisher = {IEEE Computer Society Press},
  url = {http://www.debruijn.net/publications/frames-ruleml.pdf},
  abstract = {Many popular ontology languages are based on
                  (subsets of) first-order predicate logic, where
                  classes are modeled as unary predicates and
                  properties as binary predicates. Specifically, the
                  ontology language OWL DL is based on the Description
                  Logic $\mathcal{SHOIQ}$. F-Logic is an ontology
                  language which is also based on first-order logic,
                  but classes and properties are modeled as terms,
                  rather than predicates.  In this paper we define a
                  translation from predicate-based ontologies to
                  F-Logic ontologies and show that this translation
                  preserves entailments for large classes of
                  ontologies, including most of OWL DL. We define the
                  class of equality-safe ($\mathcal{E}$-safe)
                  formulas, show that the Description Logic
                  $\mathcal{SHIQ}$ is $\mathcal{E}$-safe, and show
                  that the translation preserves validity of
                  $\mathcal{E}$-safe formulas. Finally, we use these
                  results to close the open problems of layering
                  F-Logic programming on top of Description Logic
                  Programs and language layering in WSML.}
}
@inproceedings{bruijn06-repres-issues-about-combin-of,
  bibsection = {CONF},
  author = {Bruijn, Jos de and Thomas Eiter and Axel Polleres and
                  Hans Tompits },
  title = {On Representational Issues about Combinations of
                  Classical Theories with Nonmonotonic Rules},
  booktitle = {Proceedings of the 1st International Conference on Knowledge Science, Engineering and Management (KSEM2006)},
  pages = {1--22},
  year = {2006},
  address = {Guilin, China},
  month = {August 5-8},
  number = {4092},
  series = {Lecture Notes in Artificial Intelligence},
  publisher = {Springer},
  url = {http://www.debruijn.net/publications/deri-tr-2006-05-29.pdf},
  abstract = {In the context of current efforts around
                  Semantic-Web languages, the combination of classical
                  theories in classical first-order logic (and in
                  particular of ontologies in various description
                  logics) with rule languages rooted in logic
                  programming is receiving considerable
                  attention. Existing approaches such as SWRL,
                  dl-programs, and $\mathcal{DL}$+log, differ
                  significantly in the way ontologies interact with
                  (nonmonotonic) rules bases. In this paper, we
                  identify fundamental representational issues which
                  need to be addressed by such combinations and
                  formulate a number of formal principles which help
                  to characterize and classify existing and possible
                  future approaches to the combination of rules and
                  classical theories. We use the formal principles to
                  explicate the underlying assumptions of current
                  approaches. Finally, we propose a number of
                  settings, based on our analysis of the
                  representational issues and the fundamental
                  principles underlying current approaches.  }
}
@inproceedings{heymans06-g-hybrid-knowl-bases,
  bibsection = {CONF},
  author = {Stijn Heymans and Livia Predoiu and Cristina Feier
                  and Bruijn, Jos de and Davy Van Nieuwenborgh},
  title = {G-Hybrid Knowledge Bases},
  booktitle = {Proceedings of the ICLP'06 Workshop on Applications
                  of Logic Programming in the Semantic Web and
                  Semantic Web Services (ALPSWS2006)},
  pages = {39--54},
  publisher = {CEUR Workshop Proceedings},
  volume = {196},
  year = {2006},
  address = {Seattle, Washington, USA},
  month = {August 16},
  url = {http://www.debruijn.net/publications/ghybrid-alpsws.pdf},
  abstract = {Recently, there has been a lot of interest in the
                  integration of Description Logics and rules on the
                  Semantic Web.  We define \emph{g-hybrid knowledge
                  bases} as knowledge bases that consist of a
                  Description Logic knowledge base and a
                  \emph{guarded} logic program, similarly to the
                  $\mathcal{DL}\text{+}log$ knowledge bases from
                  Rosati. G-hybrid knowledge bases enable an
                  integration of Description Logics and Logic
                  Programming where, unlike in other approaches,
                  variables in the rules of a guarded program do not
                  need to appear in positive non-DL atoms of the body:
                  DL atoms can act as \emph{guards} as
                  well. Decidability of satisfiability checking of
                  g-hybrid knowledge bases is shown for the particular
                  DL $DLRO^{-\{\leq\}}$, which is close to, and in
                  some respects more expressive than, OWL DL, by a
                  reduction to guarded programs under an open answer
                  set semantics.  Moreover, we show
                  2-EXPTIME-completeness for satisfiability checking
                  of those $DLRO^{-\{\leq\}}$ g-hybrid knowledge
                  bases. Finally, we discuss advantages and
                  disadvantages of our approach compared with
                  $\mathcal{DL}\text{+}log$ knowledge bases.}
}
@inproceedings{debr-etal-2005c,
  bibsection = {CONF},
  author = {Bruijn, Jos de and Axel Polleres and Rub\'{e}n Lara
                  and Dieter Fensel},
  title = {{OWL} {DL} vs. {OWL} {Flight}: Conceptual Modeling
                  and Reasoning on the Semantic Web},
  booktitle = {Proceedings of the 14th International World Wide Web
                  Conference (WWW2005)},
  pages = {623--632},
  year = {2005},
  publisher = {ACM Press},
  address = {Chiba, Japan},
  url = {http://www.debruijn.net/publications/f525-debruijn.pdf},
  abstract = {The Semantic Web languages RDFS and OWL have been
                  around for some time now. However, the presence of
                  these languages has not brought the breakthrough of
                  the Semantic Web the creators of the languages had
                  hoped for. OWL has a number of problems in the area
                  of interoperability and usability in the context of
                  many practical application scenarios which impede
                  the connection to the Software Engineering and
                  Database communities. In this paper we present OWL
                  Flight, which is loosely based on OWL, but the
                  semantics is grounded in Logic Programming rather
                  than Description Logics, and it borrows the
                  constraint-based modeling style common in
                  databases. This results in different types of
                  modeling primitives and enforces a different style
                  of ontology modeling. We analyze the modeling
                  paradigms of OWL DL and OWL Flight, as well as
                  reasoning tasks supported by both languages. We
                  argue that different applications on the Semantic
                  Web require different styles of modeling and thus
                  both types of languages are required for the
                  Semantic Web. }
}
@inproceedings{bruijn05-logic-rdf,
  bibsection = {CONF},
  author = {Bruijn, Jos de and Enrico Franconi and Sergio
                  Tessaris},
  title = {Logical reconstruction of {RDF} and ontology
                  languages},
  booktitle = {Proceedings of the 3rd Workshop on Principles and Practice of Semantic Web Reasoning (PPSWR2005)},
  page = {65--71},
  year = {2005},
  address = {Dagstuhl, Germany},
  month = {September},
  number = {3703},
  series = {Lecture Notes in Computer Science},
  publisher = {Springer},
  url = {http://www.debruijn.net/publications/ppswr-05.pdf},
  abstract = {In this sketchy paper we introduce a logical
                  reconstruction of the RDF family of languages and
                  the OWL-DL family of languages. We prove that our
                  logical framework is equivalent to the standard W3C
                  definitions of RDF and OWL-DL/Lite. The main aim is
                  to have a unified model theoretic semantics for both
                  worlds. As a consequence we get various complexity
                  results and a model theoretic semantics for basic
                  SPARQL. }
}
@inproceedings{bruijn05-logic-rdf2,
  bibsection = {CONF},
  author = {Bruijn, Jos de and Enrico Franconi and Sergio
                  Tessaris},
  title = {Logical reconstruction of normative {RDF}},
  booktitle = {OWL: Experiences and Directions Workshop (OWLED-2005)},
  year = {2005},
  address = {Galway, Ireland},
  month = {November},
  url = {http://www.debruijn.net/publications/owl-05.pdf},
  abstract = {In this sketchy pap er we introduce a logical
                  reconstruction of the RDF family of languages and
                  the OWL-DL family of languages. We prove that our
                  logical framework is equivalent to the normative W3C
                  definitions of RDF/RDFS and OWL-DL/Lite. The main
                  aim is to have a unified model theoretic semantics
                  for b oth worlds. As a consequence we get various
                  complexity results and a model theoretic semantics
                  for basic SPARQL. }
}
@inproceedings{debr-etal-2005f,
  bibsection = {CONF},
  author = {Bruijn, Jos de and Holger Lausen and Axel Polleres
                  and Dieter Fensel},
  title = {The {WSML} Rule Languages for the Semantic Web},
  booktitle = {Proceedings of the W3C Workshop on Rule Languages for Interoperability},
  year = {2005},
  address = {Washington DC, USA},
  month = {April},
  note = {Position paper},
  url = {http://www.w3.org/2004/12/rules-ws/paper/128/},
  abstract = {The Web Service Modeling Language WSML provides a
                  framework for the modeling of ontologies and
                  semantic Web services based on the conceptual model
                  of the Web Service Modeling Ontology. In this paper
                  we describe the two rule-based WSML-variants and
                  outline our position with respect to a rule language
                  for the Semantic Web. The first rule-based WSML
                  variant, WSML-Flight, semantically corresponds to
                  the Datalog fragment of F-Logic, extended with
                  inequality in the body and locally stratified
                  negation under the Perfect model semantics. The
                  second, WSML-Rule, is an extension of WSML-Flight to
                  the logic programming subset of F-Logic which allows
                  the use of function symbols and unsafe rules (i.e.,
                  there may be variables in rule heads which do not
                  occur in the body).}
}
@inproceedings{kifer05-realis-archit-seman-web,
  bibsection = {CONF},
  author = {Michael Kifer and Bruijn, Jos de and Harold Boley and
                  Dieter Fensel},
  title = {A Realistic Architecture for the Semantic Web},
  booktitle = {Proceedings of the 1st International Conference on Rules and Rule Markup Languages for the Semantic Web (RuleML2005)},
  pages = {17--29},
  year = {2005},
  address = {Galway, Ireland},
  month = {November},
  number = {3791},
  series = {Lecture Notes in Computer Science},
  publisher = {Springer},
  url = {http://www.debruijn.net/publications/msa-ruleml05.pdf},
  abstract = {In this paper we argue that a realistic architecture
                  for the Semantic Web must be based on multiple
                  independent, but interoperable, stacks of
                  languages. In particular, we argue that there is a
                  very important class of rule-based languages, with
                  over thirty years of history and experience, which
                  cannot be layered on top of OWL and must be included
                  in the Semantic Web architecture alongside with the
                  stack of OWL-based languages. The class of languages
                  we are after includes rules in the Logic Programming
                  style, which support default negation. We briefly
                  survey the logical foundations of these languages
                  and then discuss an interoperability framework in
                  which such languages can co-exist with OWL and its
                  extensions. }
}
@inproceedings{laus-etal-2005,
  bibsection = {CONF},
  author = {Holger Lausen and Bruijn, Jos de and Axel Polleres
                  and Dieter Fensel},
  title = {{WSML} - a Language Framework for Semantic Web
                  Services},
  booktitle = {Proceedings of the W3C Workshop on Rule Languages for Interoperability},
  year = {2005},
  address = {Washington DC, USA},
  month = {April},
  note = {Position paper},
  url = {http://www.w3.org/2004/12/rules-ws/paper/44/},
  abstract = {The Web Service Modeling Language (WSML) provides a
                  framework of different language variants to describe
                  semantic Web services. This paper presents the
                  design rationale and relation with existing language
                  recommendations. WSML is a frame based language with
                  an intuitive human readable syntax and XML and RDF
                  exchange syntaxes, as well as a mapping to OWL. It
                  provides different variants, allowing for open and
                  closed world modeling; it is a fully-fledged
                  ontology and rule language with defined variants
                  grounded in well known formalisms, namely Datalog,
                  Description Logic and Frame Logic. Taking the key
                  aspects of WSML as a starting point, we rationalize
                  the design decisions which we consider relevant in
                  designing a proper layering of ontology and rule
                  languages for the Semantic Web and semantic Web
                  services.}
}
@inproceedings{scharffe05-languag-specif-mappin-ontol,
  bibsection = {CONF},
  author = {Fran\c{c}ois Scharffe and Bruijn, Jos de},
  title = {A Language to Specify Mappings between Ontologies},
  booktitle = {Proceedings of the 1st International Conference on Signal-Image Technology and Internet-Based Systems (SITIS2005)},
  year = {2005},
  address = {Yandou\'{e}, Cameroon},
  month = {November},
  publisher = {Dicolor Press},
  url = {http://www.debruijn.net/publications/mapping-language.pdf},
  abstract = {The ontology mediation field aims at finding
                  techniques and frameworks to allow interoperability
                  between overlapping heterogeneous ontologies. One of
                  the solutions is to designing mappings that link the
                  corresponding entities. Many systems and algorithms
                  have been built by different parties, but each
                  system represents the mappings in its own format. To
                  allow reusability of the mapping tools and of the
                  results of the algorithms, we have designed a
                  language to express these mappings. In this paper,
                  we will present this mapping language. }
}
@inproceedings{debr-2004,
  bibsection = {CONF},
  author = {Bruijn, Jos de},
  title = {Semantic Integration of Disparate Data Sources in
                  the COG Project},
  booktitle = {Proceedings of the 6th International Conference on
                  Enterprise Information Systems (ICEIS2004)},
  year = {2004},
  publisher = {ICEIS Press},
  page = {9--14},
  address = {Porto, Portugal},
  url = {http://www.debruijn.net/publications/COG-ICEIS2004.pdf},
  abstract = {We present a novel approach to the integration of
                  structured information sources in enterprises, based
                  on Semantic Web technology. The semantic information
                  integration approach presented in this paper was
                  applied in the COG project. We describe Unicorn's
                  Semantic Information Management along with the
                  Unicorn Workbench tool, which is a component part of
                  the Unicorn System, and how they were applied in the
                  project to solve the information integration
                  problem. We used the Semantic Information Management
                  Methodology and the Unicorn Workbench tool to create
                  an Information Model (an ontology) based on data
                  schemas taken from the automotive industry. We map
                  these data schemas to the Information Model in order
                  to make the meaning of the concepts in the data
                  schemas explicit and relate them to each other,
                  thereby creating an information architecture that
                  provides a unified view of the data sources in the
                  organization. }
}
@inproceedings{debr-laus-2004,
  bibsection = {CONF},
  author = {Bruijn, Jos de and Holger Lausen},
  title = {Active Ontologies for Data Source Queries},
  booktitle = {Proceedings of the 1st European Semantic Web Symposium (ESWS2004)},
  year = {2004},
  publisher = {Springer},
  address = {Heraklion, Greece},
  number = {3053},
  series = {Lecture Notes in Computer Science},
  url = {http://www.debruijn.net/publications/esws2004-cog-querying.pdf},
  abstract = {In this paper we describe the work that was done in
                  the Corporate Ontology Grid (COG) project on the
                  querying of existing legacy data sources from the
                  automotive industry using ontology technology and a
                  conceptual ontology query language. We describe the
                  conceptual ontology query language developed by
                  Unicorn, the querying support provided by the
                  Unicorn Workbench, and describe the use of these
                  queries in the run-time architecture built in the
                  COG pro ject. }
}
@inproceedings{lara03-seman-web-servic,
  bibsection = {CONF},
  author = {Rub\'{e}n Lara and Holger Lausen and Sinuh\'{e}
                  Arroyo and Bruijn, Jos de and Dieter Fensel},
  title = {Semantic Web Services: description requirements and
                  current technologies},
  booktitle = {International Workshop on Electronic Commerce,
                  Agents, and Semantic Web Services},
  year = {2003},
  address = {Pittsburg, PA, USA},
  month = {September},
  url = {http://www.debruijn.net/publications/sws-description.pdf},
  abstract = {Semantic Web Services aim at providing a new level
                  of functionality on top of the current Web and
                  current services, by enabling automatic discovery,
                  composition, invocation and interoperation of Web
                  Services. Different efforts are addressing some of
                  the requirements to enable such next generation
                  services, with different degree of
                  success. Nevertheless, to achieve the main goals
                  addressed by Semantic Web Services, an appropriate
                  semantic description, supporting automation of
                  discovery, composition, invocation and
                  interoperation, must be defined. In this paper, a
                  set of requirements on the information a Semantic
                  Web Service must expose in order to fulfill these
                  major objectives is presented. These requirements
                  are related to the different initiatives in the
                  area, and proposals for useful extensions and
                  combinations of these efforts are discussed. }
}