Towards a Precise Semantics for Object-Oriented Modeling Techniques

In this paper we present a possible way how a precise semantics of object oriented modeling techniques can be achieved and what the possible benefits are .We outline the main modeling techniques used in the SysLab project sketch how a precise semantics can be given and how this semantics can be used during the development process.Comment: 6 pages, 0 figure

An Introduction to Ontologies and Ontology Engineering

In the last decades, the use of ontologies in information systems has become more and more popular in various fields, such as web technologies, database integration, multi agent systems, natural language processing, etc. Artificial intelligent researchers have initially borrowed the word “ontology” from Philosophy, then the word spread in many scientific domain and ontologies are now used in several developments. The main goal of this chapter is to answer generic questions about ontologies, such as: Which are the different kinds of ontologies? What is the purpose of the use of ontologies in an application? Which methods can I use to build an ontology

Comparación de redes semánticas naturales mediante un modelo de recuperación de información

Actualmente la técnica de Redes Semánticas Naturales (RSN) es usada ampliamente para la representación de significados, es de interés comparar redes de diferentes poblaciones acerca de una misma temática. En este trabajo se presenta un nuevo modelo de comparación entre RSN desde una perspectiva de Recuperación de Información para mejorar el alcance y optimizar la forma de comparar dos RSN, asimismo se genera un método de visualización de las RSN que permita representar a las redes así como a la similitud entre ellas. Para realizar esta investigación, se generaron diez RSN de la temática de Ecología con la participación de 163 individuos; se adaptó la definición del Modelo de Espacio Vectorial (MEV) para comparar las RSN, como resultado de la comparación se obtuvo el valor de tres medidas de similitud: cosenoidal, el coeficiente de Dice y el coeficiente de Jaccard; se calcularon coeficientes de correlación de Pearson para determinar la relación entre estas medidas y el resultado indica que la correlación que existe entre las medidas de similitud es positiva muy fuerte. Se generaron representaciones visuales de las redes mediante nubes de etiquetas en donde el peso de cada definidor está relacionado con el tamaño y color con el que se muestra, se identificó que esta visualización es una técnica útil para representar RSN así como para evaluar de manera cualitativa la similitud entre ellas. Se llevó a cabo el análisis de los resultados obtenidos en la comparación de manera cuantitativa y cualitativa el cual indica que sí es posible realizar la comparación entre RSN con este método aun cuando la cantidad de participantes en las redes sea distinta, lo que proporciona una nueva herramienta para la amplia variedad de campos en los que se usan la Redes Semánticas Naturales

Towards a precise semantics for object-oriented modeling techniques

In this paper, we demonstrate how a precise semantics of object-oriented modeling techniques can be achieved, and what the possible bene ts are. We outline the main modeling techniques used in the SysLab project, sketch, how a precise semantics can be given, and how this semantics can be used during the development process

A distributed architecture for environmental information systems

The increasing availability and variety of large environmental data sets is opening new opportunities for data mining and useful cross-referencing of disparate environmental data sets distributed over a network. In order to take advantage of these opportunities, environmental information systems will need to operate effectively in a distributed, open environment. In this paper, we describe the New Zealand Distributed Information System (NZDIS) software architecture for environmental information systems. In order to optimise extensibility, openness, and flexible query processing, the architecture is organised into collaborating software agents that communicate by means of a standard declarative agent communication language. The metadata of environmental data sources are stored as part of agent ontologies, which represent information models of the domain of the data repository. The agents and the associated ontological framework are designed as much as possible to take advantage of standard object-oriented technology, such as CORBA, UML, and OQL, in order to enhance the openness and accessibility of the system.Unpublished[1] T. Mowbray and R. Malveau, CORBA Design Patterns, John Wiley & Sones, Inc., NewYork, 1997. [2] J. Searle, Speech Acts, Cambridge University Press, Cambridge, 1969. [3] T. R. Gruber, “A Translation Approach to Portable Ontology Specifications”, Knowledge Acquisition, 5(2), 1993, pp. 199-220. [4] T. Finin and R. Fritzson and D. Mckay and R. McEntire, “KQML}: An Information and Knowledge Exchange Protocol”, in Knowledge Building and Knowledge Sharing, K. Fuchi and T. Yokoi (eds.) Ohmsha and IOS Press, 1994. [5] http://www.fipa.org. [6] R. G. G. Cattell, D. K. Barry, D. (eds), The Object Database Standard : Odmg 2.0, Morgan Kaufmann, 1997. [7] ANSI X3T2 Ad Hoc Group on KIF, “Knowledge Interchange Format specification” (Working Draft), http://logic.stanford.edu/kif/specification.html, March 1995. [8] R. J. Brachman and J. G. Schmolze, “An overview of the KL-ONE knowledge representation system”, Cognitive Science, 9(2), 171-216, 1985. [9] G. Booch, J. Rumbaugh, and I. Jacobson, The Unified Modeling Language User Guide, Addison-Wesley, Reading, MA, 1999. [10] B. Owsnicki-Klewe, “A General Characterisation of Term Description Languages, Sorts and Types in Artificial Intelligence, K.-H. Blasius, U. Hedtstuck and C. Rollinger (eds.), Springer-Verlag LNAI, 418, 1990, pp. 183-189. [11] J. B. Warmer and A. G. Kleppe, The Object Constraint Language: Precise Modeling with UML, Addison-Wesley, Reading, MA, 1998. [12] R. Breu, R. Grosu, F. Huber, B. Rumpe, and W. Schwerin, "Towards a Precise Semantics for Object-Oriented Modeling Techniques", Proceedings ECOOP'97 Workshop on Precise Semantics for Object-Oriented Modeling Techniques, H. Kilov and B. Rumpe (eds.), Technische Universitat Munchen, TUM-I9725, 1997, pp. 53--59. [13] A. Evans, R. France, Kevin Lano, and B. Rumpe, "Developing the {UML} as a Formal Modelling Notation", Proceedings of UML'98 International Workshop France, June 3 - 4, 1998, P. Muller and J. Bezivin, ESSAIM, Mulhouse, France, 1998, pp. 297--307. [14] G. Overgaard, "A Formal Approach to Relationships in The Unified Modeling Language", Proceedings PSMT'98 Workshop on Precise Semantics for Modeling Techniques, M. Broy, D. Coleman, T. S. E. Maibaum, and B. Rumpe, Technische Universität München, TUM-I9803, 1998. [15] M. Richters and M. Gogolla, "On Formalizing the UML Object Constraint Language OCL", Proc. 17th Int. Conf. Conceptual Modeling (ER'98), T. Ling, and S. Ram, and M. Lee, Springer, Berlin, LNCS 1507, 1998. [16] A. Hamie, J. Howse, and S. Kent, "Interpreting the Object Constraint Language", Proceedings of the 5th Asia Pacific Software Engineering Conference (APSEC'98), IEEE Press, 1998. [17] R. J. Bayardo, Jr.,W. Bohrer, R. Brice, A. Cichocki, J. Fowler, A. Helal, V. Kashyap, T. Ksiezyk, G. Martin, M. Nodine, M. Rashid, M. Rusinkiewicz, R. Shea, C. Unnikrishnan, A. Unruh, D. Woelk, "InfoSleuth: agent-based semantic integration of information in open and dynamic environments", Proceedings of the ACM SIGMOD International Conference on Management of Data, J. Peckham (ed.) June 1997, pp. 195-206. [18] Distributed Systems Technology Centre, “Meta Object Facility Frequently Asked Questions, http://www.dstc.edu.au/Meta-Object-Facility/MOFAQ.html, 1998. [19] A. Y. Levy, D.Srivastava and T. Kirk. “Data Model and Query Evaluation in Global Information Systems” Journal of Intelligent Information Systems, 5(2), September 1995. [20] Y. Arens, C. A. Knoblock, and W. Shen, “Query Processing in the SIMS Information Mediator”, Advanced Planning Technology, Tate, A. (ed.), AAAI Press, Menlo Park, CA, 1996. [21] E. Mena, V. Kashyap, A. Sheth, and A. Illarramendi, “OBSERVER: An approach for query processing in global information systems based on interoperation across pre-existing ontologies”, Proceedings of First IFCIS International Conference on Cooperative Information Systems (CoopIS’96), June 1996

A distributed architecture for environmental information systems

The increasing availability and variety of large environmental data sets is opening new opportunities for data mining and useful cross-referencing of disparate environmental data sets distributed over a network. In order to take advantage of these opportunities, environmental information systems will need to operate effectively in a distributed, open environment. In this paper, we describe the New Zealand Distributed Information System (NZDIS) software architecture for environmental information systems. In order to optimise extensibility, openness, and flexible query processing, the architecture is organised into collaborating software agents that communicate by means of a standard declarative agent communication language. The metadata of environmental data sources are stored as part of agent ontologies, which represent information models of the domain of the data repository. The agents and the associated ontological framework are designed as much as possible to take advantage of standard object-oriented technology, such as CORBA, UML, and OQL, in order to enhance the openness and accessibility of the system.Unpublished[1] T. Mowbray and R. Malveau, CORBA Design Patterns, John Wiley & Sones, Inc., NewYork, 1997. [2] J. Searle, Speech Acts, Cambridge University Press, Cambridge, 1969. [3] T. R. Gruber, “A Translation Approach to Portable Ontology Specifications”, Knowledge Acquisition, 5(2), 1993, pp. 199-220. [4] T. Finin and R. Fritzson and D. Mckay and R. McEntire, “KQML}: An Information and Knowledge Exchange Protocol”, in Knowledge Building and Knowledge Sharing, K. Fuchi and T. Yokoi (eds.) Ohmsha and IOS Press, 1994. [5] http://www.fipa.org. [6] R. G. G. Cattell, D. K. Barry, D. (eds), The Object Database Standard : Odmg 2.0, Morgan Kaufmann, 1997. [7] ANSI X3T2 Ad Hoc Group on KIF, “Knowledge Interchange Format specification” (Working Draft), http://logic.stanford.edu/kif/specification.html, March 1995. [8] R. J. Brachman and J. G. Schmolze, “An overview of the KL-ONE knowledge representation system”, Cognitive Science, 9(2), 171-216, 1985. [9] G. Booch, J. Rumbaugh, and I. Jacobson, The Unified Modeling Language User Guide, Addison-Wesley, Reading, MA, 1999. [10] B. Owsnicki-Klewe, “A General Characterisation of Term Description Languages, Sorts and Types in Artificial Intelligence, K.-H. Blasius, U. Hedtstuck and C. Rollinger (eds.), Springer-Verlag LNAI, 418, 1990, pp. 183-189. [11] J. B. Warmer and A. G. Kleppe, The Object Constraint Language: Precise Modeling with UML, Addison-Wesley, Reading, MA, 1998. [12] R. Breu, R. Grosu, F. Huber, B. Rumpe, and W. Schwerin, "Towards a Precise Semantics for Object-Oriented Modeling Techniques", Proceedings ECOOP'97 Workshop on Precise Semantics for Object-Oriented Modeling Techniques, H. Kilov and B. Rumpe (eds.), Technische Universitat Munchen, TUM-I9725, 1997, pp. 53--59. [13] A. Evans, R. France, Kevin Lano, and B. Rumpe, "Developing the {UML} as a Formal Modelling Notation", Proceedings of UML'98 International Workshop France, June 3 - 4, 1998, P. Muller and J. Bezivin, ESSAIM, Mulhouse, France, 1998, pp. 297--307. [14] G. Overgaard, "A Formal Approach to Relationships in The Unified Modeling Language", Proceedings PSMT'98 Workshop on Precise Semantics for Modeling Techniques, M. Broy, D. Coleman, T. S. E. Maibaum, and B. Rumpe, Technische Universität München, TUM-I9803, 1998. [15] M. Richters and M. Gogolla, "On Formalizing the UML Object Constraint Language OCL", Proc. 17th Int. Conf. Conceptual Modeling (ER'98), T. Ling, and S. Ram, and M. Lee, Springer, Berlin, LNCS 1507, 1998. [16] A. Hamie, J. Howse, and S. Kent, "Interpreting the Object Constraint Language", Proceedings of the 5th Asia Pacific Software Engineering Conference (APSEC'98), IEEE Press, 1998. [17] R. J. Bayardo, Jr.,W. Bohrer, R. Brice, A. Cichocki, J. Fowler, A. Helal, V. Kashyap, T. Ksiezyk, G. Martin, M. Nodine, M. Rashid, M. Rusinkiewicz, R. Shea, C. Unnikrishnan, A. Unruh, D. Woelk, "InfoSleuth: agent-based semantic integration of information in open and dynamic environments", Proceedings of the ACM SIGMOD International Conference on Management of Data, J. Peckham (ed.) June 1997, pp. 195-206. [18] Distributed Systems Technology Centre, “Meta Object Facility Frequently Asked Questions, http://www.dstc.edu.au/Meta-Object-Facility/MOFAQ.html, 1998. [19] A. Y. Levy, D.Srivastava and T. Kirk. “Data Model and Query Evaluation in Global Information Systems” Journal of Intelligent Information Systems, 5(2), September 1995. [20] Y. Arens, C. A. Knoblock, and W. Shen, “Query Processing in the SIMS Information Mediator”, Advanced Planning Technology, Tate, A. (ed.), AAAI Press, Menlo Park, CA, 1996. [21] E. Mena, V. Kashyap, A. Sheth, and A. Illarramendi, “OBSERVER: An approach for query processing in global information systems based on interoperation across pre-existing ontologies”, Proceedings of First IFCIS International Conference on Cooperative Information Systems (CoopIS’96), June 1996

UML as an ontology modelling language

Current tools and techniques for ontology development are based on the traditions of AI knowledge representation research. This research has led to popular formalisms such as KIF and KL-ONE style languages. However, these representations are little known outside AI research laboratories. In contrast, commercial interest has resulted in ideas from the object-oriented programming community maturing into industry standards and powerful tools for object-oriented analysis, design and implementation. These standards and tools have a wide and rapidly growing user community. This paper examines the potential for object-oriented standards to be used for ontology modelling, and in particular presents an ontology representation language based on a subset of the Unified Modeling Language together with its associated Object Constraint Language.Unpublished[Bateman et al., 1995] John A. Bateman, Renate Henschel, and Fabio Rinaldi. The generalized upper model 2.0. http://www.darmstadt.gmd.de/publish/komet/genum/newUM.html, 1995. [Bayardo et al., 1997] R. J. Bayardo, Jr., W. Bohrer, R. Brice, A. Cichocki, J. Fowler, A. Helal, V. Kashyap, T. Ksiezyk, G. Martin, M. Nodine, M. Rashid, M. Rusinkiewicz, R. Shea, C. Unnikrishnan, A. Unruh, and D. Woelk. Infosleuth: agent-based semantic integration of information in open and dynamic environments. In Joan Peckham, editor, Proceedings of the ACM SIGMOD international conference on management of data, SIGMOD Record 26(2), pages 195–206, June 1997. [Brachman and Schmolze, 1985] R. J. Brachman and J. G. Schmolze. An overview of the KL-ONE knowledge representation system. Cognitive Science, 9(2):171–216, April 1985. [Breu et al., 1997] Ruth Breu, Radu Grosu, Franz Huber, Bernhard Rumpe, and Wolfgang Schwerin. Towards a precise semantics for object-oriented modeling techniques. In Haim Kilov and Bernhard Rumpe, editors, Proceedings ECOOP’97 Workshop on Precise Semantics for Object-Oriented Modeling Techniques, pages 53–59. Technische Universität München, TUM-I9725, 1997. [Crawley et al., 1997] Stephen Crawley, Simon McBride, and Kerry Raymond. Meta-Object Facility tutorial (draft). http://www.dstc.edu.au/Meta-Object-Facility/Tutorial.html, 1997. [Donini et al., 1996] F. Donini, M. Lenzerini, D. Nardi, and A. Schaerf. Reasoning in description logics. In G. Brewka, editor, Principles of Knowledge Representation and Reasoning, Studies in Logic, Language and Information, pages 193–238. CLSI Publications, 1996. [DSTC, 1998] Distributed Systems Technology Centre. Meta Object Facility frequently asked questions. http://www.dstc.edu.au/Meta-Object-Facility/MOFAQ.html, 1998. [DSTC, 1999] Distributed Systems Technology Centre. XMI spec recommended. News item on Meta-Object Facility Information Web Page, http://www.dstc.edu.au/Meta-Object-Facility/, January 1999. [Evans et al., 1998] Andy Evans, Robert France, Kevin Lano, and Bernhard Rumpe. Developing the UML as a formal modelling notation. In Pierre-Alain Muller and Jean Bézivin, editors, Proceedings of UML’98 International Workshop, Mulhouse, France, June 3 - 4, 1998, pages 297–307. ESSAIM, Mulhouse, France, 1998. [Farquhar et al., 1996] Adam Farquhar, Richard Fikes, and James Rice. The Ontolingua Server: a tool for collaborative ontology construction. In Proceedings of the 10th Knowledge Acquisition for Knowledge-Based Systems Workshop (KAW’96), 1996. [Genesereth and Ketchpel, 1994] M. R. Genesereth and S. P. Ketchpel. Software agents. Communications of the ACM, 37(7):48–53, July 1994. [Haimowitz et al., 1988] Ira J. Haimowitz, Ramesh S. Patil, and Peter Szolovits. Representing medical knowledge in a terminological language is difficult. In Proceedings of the Symposium on Computer Applications in Medical Care, pages 101–105. IEEE Computer Society Press, 1988. [Hamie et al., 1998a] Ali Hamie, Franco Civello, John Howse, Stuart Kent, and Richard Mitchell. Reflections on the Object Constraint Language. In Pierre-Alain Muller and Jean Bézivin, editors, Proceedings of UML’98 International Workshop, Mulhouse, France, June 3–4, 1998, pages 137–145. ESSAIM, Mulhouse, France, 1998. [Hamie et al., 1998b] Ali Hamie, John Howse, and Stuart Kent. Interpreting the Object Constraint Language. In Proceedings of the 5th Asia Pacific Software Engineering Conference (APSEC’98). IEEE Press, 1998. [ISI, 1998] Information Sciences Institute. Loom project home page. http://www.isi.edu/isd/LOOM/LOOM-HOME.html, 1998. [Knoblock and Ambite, 1997] C. A. Knoblock and J. L. Ambite. Agents for information gathering. In J. Bradshaw, editor, Software Agents. AAAI/MIT Press, 1997. [KSL, 1994] Knowledge Systems Laboratory. The Frame Ontology. ftp://ftp.ksl.stanford.edu/pub/knowledge-sharing/ontologies/html/frame-ontology/frame-ontology. lisp.html, 1994. [Levesque and Brachman, 1985] Hector J. Levesque and Ronald J. Brachman. A fundamental tradeoff in knowledge representation and reasoning (revised version). In Ronald J. Brachman and Hector J. Levesque, editors, Readings in Knowledge Representation, pages 42–70. Morgan Kaufman, 1985. [Mena et al., 1999] E. Mena, A. Illarramendi, V. Kashyap, and A. Sheth. OBSERVER: An approach for query processing in global information systems based on interoperation across pre-existing ontologies. Distributed and Parallel Databases, 1999. (to appear). [NCITS, 1998] National Committee for Information Technology Standards, Technical Committee T2 (Information Interchange and Interpretation). Draft proposed American national standard for Knowledge Interchange Format. http://logic.stanford.edu/kif/dpans.html, 1998. [Nebel, 1990] B. Nebel. Reasoning and Revision in Hybrid Representation Systems. Lecture Notes in Artificial Intelligence, number 422. Springer-Verlag, 1990. [OMG,1997a] ObjectManagementGroup.UMLsemantics, version 1.1. ftp://ftp.omg.org/pub/docs/ad/97-08-04.pdf, September 1997. [OMG, 1997b] Object Management Group. Object Constraint Language specification. ftp://ftp.omg.org/pub/docs/ ad/97-08-08.pdf, September 1997. [OMG, 1997c] Object Management Group. MOF specification. http://www.omg.org/techprocess/meetings/schedule/Technology Adoptions.html#tbl MOF Specification, 1997. [OMG, 1998] Object Management Group. OMG homepage. http://www.omg.org/, 1998. [OMG, 1999] Object Management Group. Stream-based model interchange Web page. http://www.omg.org/techprocess/meetings/schedule/Stream-based_Model_Interchange.html, 1999. [Övergaard, 1998] Gunnar Övergaard. A formal approach to relationships in the Unified Modeling Language. In Manfred Broy, Derek Coleman, Tom S. E. Maibaum, and Bernhard Rumpe, editors, Proceedings PSMT’98 Workshop on Precise Semantics for Modeling Techniques. Technische Universität München, TUM-I9803, 1998. [Owsnicki-Klewe, 1990] Bernd Owsnicki-Klewe. A general characterisation of term description languages. In K.-H. Bläsius, U. Hedtstück, and C. Rollinger, editors, Sorts and Types in Artificial Intelligence, Lecture Notes in Artificial Intelligence, number 418, pages 183–189. Springer-Verlag, 1990. [Richters and Gogolla, 1998] Mark Richters and Martin Gogolla. On formalizing the UML Object Constraint Language OCL. In Tok Wang Ling, Sudha Ram, and Mong Li Lee, editors, Proc. 17th Int. Conf. Conceptual Modeling (ER’98). Lecture Notes in Computer Science, number 1507, Springer-Verlag, 1998. [Rumbaugh et al., 1998] James Rumbaugh, Ivar Jacobson, and Grady Booch. The Unified Modeling Language Reference Manual. Addison-Wesley, 1998. [SMI, 1998] Stanford Medical Informatics. The Protégé project. http://smi-web.stanford.edu/projects/protege/, 1998. [Warmer and Kleppe, 1998] Jos B. Warmer and Anneke G. Kleppe. The Object Constraint Language: Precise Modeling With UML. Addison-Wesley, 1998

UML as an ontology modelling language

Current tools and techniques for ontology development are based on the traditions of AI knowledge representation research. This research has led to popular formalisms such as KIF and KL-ONE style languages. However, these representations are little known outside AI research laboratories. In contrast, commercial interest has resulted in ideas from the object-oriented programming community maturing into industry standards and powerful tools for object-oriented analysis, design and implementation. These standards and tools have a wide and rapidly growing user community. This paper examines the potential for object-oriented standards to be used for ontology modelling, and in particular presents an ontology representation language based on a subset of the Unified Modeling Language together with its associated Object Constraint Language.Unpublished[Bateman et al., 1995] John A. Bateman, Renate Henschel, and Fabio Rinaldi. The generalized upper model 2.0. http://www.darmstadt.gmd.de/publish/komet/genum/newUM.html, 1995. [Bayardo et al., 1997] R. J. Bayardo, Jr., W. Bohrer, R. Brice, A. Cichocki, J. Fowler, A. Helal, V. Kashyap, T. Ksiezyk, G. Martin, M. Nodine, M. Rashid, M. Rusinkiewicz, R. Shea, C. Unnikrishnan, A. Unruh, and D. Woelk. Infosleuth: agent-based semantic integration of information in open and dynamic environments. In Joan Peckham, editor, Proceedings of the ACM SIGMOD international conference on management of data, SIGMOD Record 26(2), pages 195–206, June 1997. [Brachman and Schmolze, 1985] R. J. Brachman and J. G. Schmolze. An overview of the KL-ONE knowledge representation system. Cognitive Science, 9(2):171–216, April 1985. [Breu et al., 1997] Ruth Breu, Radu Grosu, Franz Huber, Bernhard Rumpe, and Wolfgang Schwerin. Towards a precise semantics for object-oriented modeling techniques. In Haim Kilov and Bernhard Rumpe, editors, Proceedings ECOOP’97 Workshop on Precise Semantics for Object-Oriented Modeling Techniques, pages 53–59. Technische Universität München, TUM-I9725, 1997. [Crawley et al., 1997] Stephen Crawley, Simon McBride, and Kerry Raymond. Meta-Object Facility tutorial (draft). http://www.dstc.edu.au/Meta-Object-Facility/Tutorial.html, 1997. [Donini et al., 1996] F. Donini, M. Lenzerini, D. Nardi, and A. Schaerf. Reasoning in description logics. In G. Brewka, editor, Principles of Knowledge Representation and Reasoning, Studies in Logic, Language and Information, pages 193–238. CLSI Publications, 1996. [DSTC, 1998] Distributed Systems Technology Centre. Meta Object Facility frequently asked questions. http://www.dstc.edu.au/Meta-Object-Facility/MOFAQ.html, 1998. [DSTC, 1999] Distributed Systems Technology Centre. XMI spec recommended. News item on Meta-Object Facility Information Web Page, http://www.dstc.edu.au/Meta-Object-Facility/, January 1999. [Evans et al., 1998] Andy Evans, Robert France, Kevin Lano, and Bernhard Rumpe. Developing the UML as a formal modelling notation. In Pierre-Alain Muller and Jean Bézivin, editors, Proceedings of UML’98 International Workshop, Mulhouse, France, June 3 - 4, 1998, pages 297–307. ESSAIM, Mulhouse, France, 1998. [Farquhar et al., 1996] Adam Farquhar, Richard Fikes, and James Rice. The Ontolingua Server: a tool for collaborative ontology construction. In Proceedings of the 10th Knowledge Acquisition for Knowledge-Based Systems Workshop (KAW’96), 1996. [Genesereth and Ketchpel, 1994] M. R. Genesereth and S. P. Ketchpel. Software agents. Communications of the ACM, 37(7):48–53, July 1994. [Haimowitz et al., 1988] Ira J. Haimowitz, Ramesh S. Patil, and Peter Szolovits. Representing medical knowledge in a terminological language is difficult. In Proceedings of the Symposium on Computer Applications in Medical Care, pages 101–105. IEEE Computer Society Press, 1988. [Hamie et al., 1998a] Ali Hamie, Franco Civello, John Howse, Stuart Kent, and Richard Mitchell. Reflections on the Object Constraint Language. In Pierre-Alain Muller and Jean Bézivin, editors, Proceedings of UML’98 International Workshop, Mulhouse, France, June 3–4, 1998, pages 137–145. ESSAIM, Mulhouse, France, 1998. [Hamie et al., 1998b] Ali Hamie, John Howse, and Stuart Kent. Interpreting the Object Constraint Language. In Proceedings of the 5th Asia Pacific Software Engineering Conference (APSEC’98). IEEE Press, 1998. [ISI, 1998] Information Sciences Institute. Loom project home page. http://www.isi.edu/isd/LOOM/LOOM-HOME.html, 1998. [Knoblock and Ambite, 1997] C. A. Knoblock and J. L. Ambite. Agents for information gathering. In J. Bradshaw, editor, Software Agents. AAAI/MIT Press, 1997. [KSL, 1994] Knowledge Systems Laboratory. The Frame Ontology. ftp://ftp.ksl.stanford.edu/pub/knowledge-sharing/ontologies/html/frame-ontology/frame-ontology. lisp.html, 1994. [Levesque and Brachman, 1985] Hector J. Levesque and Ronald J. Brachman. A fundamental tradeoff in knowledge representation and reasoning (revised version). In Ronald J. Brachman and Hector J. Levesque, editors, Readings in Knowledge Representation, pages 42–70. Morgan Kaufman, 1985. [Mena et al., 1999] E. Mena, A. Illarramendi, V. Kashyap, and A. Sheth. OBSERVER: An approach for query processing in global information systems based on interoperation across pre-existing ontologies. Distributed and Parallel Databases, 1999. (to appear). [NCITS, 1998] National Committee for Information Technology Standards, Technical Committee T2 (Information Interchange and Interpretation). Draft proposed American national standard for Knowledge Interchange Format. http://logic.stanford.edu/kif/dpans.html, 1998. [Nebel, 1990] B. Nebel. Reasoning and Revision in Hybrid Representation Systems. Lecture Notes in Artificial Intelligence, number 422. Springer-Verlag, 1990. [OMG,1997a] ObjectManagementGroup.UMLsemantics, version 1.1. ftp://ftp.omg.org/pub/docs/ad/97-08-04.pdf, September 1997. [OMG, 1997b] Object Management Group. Object Constraint Language specification. ftp://ftp.omg.org/pub/docs/ ad/97-08-08.pdf, September 1997. [OMG, 1997c] Object Management Group. MOF specification. http://www.omg.org/techprocess/meetings/schedule/Technology Adoptions.html#tbl MOF Specification, 1997. [OMG, 1998] Object Management Group. OMG homepage. http://www.omg.org/, 1998. [OMG, 1999] Object Management Group. Stream-based model interchange Web page. http://www.omg.org/techprocess/meetings/schedule/Stream-based_Model_Interchange.html, 1999. [Övergaard, 1998] Gunnar Övergaard. A formal approach to relationships in the Unified Modeling Language. In Manfred Broy, Derek Coleman, Tom S. E. Maibaum, and Bernhard Rumpe, editors, Proceedings PSMT’98 Workshop on Precise Semantics for Modeling Techniques. Technische Universität München, TUM-I9803, 1998. [Owsnicki-Klewe, 1990] Bernd Owsnicki-Klewe. A general characterisation of term description languages. In K.-H. Bläsius, U. Hedtstück, and C. Rollinger, editors, Sorts and Types in Artificial Intelligence, Lecture Notes in Artificial Intelligence, number 418, pages 183–189. Springer-Verlag, 1990. [Richters and Gogolla, 1998] Mark Richters and Martin Gogolla. On formalizing the UML Object Constraint Language OCL. In Tok Wang Ling, Sudha Ram, and Mong Li Lee, editors, Proc. 17th Int. Conf. Conceptual Modeling (ER’98). Lecture Notes in Computer Science, number 1507, Springer-Verlag, 1998. [Rumbaugh et al., 1998] James Rumbaugh, Ivar Jacobson, and Grady Booch. The Unified Modeling Language Reference Manual. Addison-Wesley, 1998. [SMI, 1998] Stanford Medical Informatics. The Protégé project. http://smi-web.stanford.edu/projects/protege/, 1998. [Warmer and Kleppe, 1998] Jos B. Warmer and Anneke G. Kleppe. The Object Constraint Language: Precise Modeling With UML. Addison-Wesley, 1998