This document discusses two main challenges in ontology engineering: ontology reusability versus usability, and ontology application dependence. Regarding reusability and usability, there is a tradeoff - an ontology can either be highly reusable across different applications or highly usable for a specific application, but not both. Regarding application dependence, representing a domain for problem-solving purposes is influenced by the problem and intended use, which can lead to conflicting axiomatizations even if they agree at the domain level. The document uses examples to illustrate these challenges.

1. ‫أكاديمية الحكومة اإللكترونية الفلسطينية‬
The Palestinian eGovernment Academy
www.egovacademy.ps
Tutorial 4: Ontology Engineering & Lexical Semantics
Session 6.1
Ontology Engineering Challenges
Dr. Mustafa Jarrar
University of Birzeit
mjarrar@birzeit.edu
www.jarrar.info
PalGov © 2011 1

2. About
This tutorial is part of the PalGov project, funded by the TEMPUS IV program of the
Commission of the European Communities, grant agreement 511159-TEMPUS-1-
2010-1-PS-TEMPUS-JPHES. The project website: www.egovacademy.ps
Project Consortium:
Birzeit University, Palestine
University of Trento, Italy
(Coordinator )
Palestine Polytechnic University, Palestine Vrije Universiteit Brussel, Belgium
Palestine Technical University, Palestine
Université de Savoie, France
Ministry of Telecom and IT, Palestine
University of Namur, Belgium
Ministry of Interior, Palestine
TrueTrust, UK
Ministry of Local Government, Palestine
Coordinator:
Dr. Mustafa Jarrar
Birzeit University, P.O.Box 14- Birzeit, Palestine
Telfax:+972 2 2982935 mjarrar@birzeit.eduPalGov © 2011
2

3. © Copyright Notes
Everyone is encouraged to use this material, or part of it, but should
properly cite the project (logo and website), and the author of that part.
No part of this tutorial may be reproduced or modified in any form or by
any means, without prior written permission from the project, who have
the full copyrights on the material.
Attribution-NonCommercial-ShareAlike
CC-BY-NC-SA
This license lets others remix, tweak, and build upon your work non-
commercially, as long as they credit you and license their new creations
under the identical terms.
PalGov © 2011 3

4. Tutorial Map
Topic Time
Session 1_1: The Need for Sharing Semantics 1.5
Session 1_2: What is an ontology 1.5
Intended Learning Objectives
A: Knowledge and Understanding Session 2: Lab- Build a Population Ontology 3
4a1: Demonstrate knowledge of what is an ontology, Session 3: Lab- Build a BankCustomer Ontology 3
how it is built, and what it is used for. Session 4: Lab- Build a BankCustomer Ontology 3
4a2: Demonstrate knowledge of ontology engineering
and evaluation. Session 5: Lab- Ontology Tools 3
4a3: Describe the difference between an ontology and a Session 6_1: Ontology Engineering Challenges 1.5
schema, and an ontology and a dictionary.
Session 6_2: Ontology Double Articulation 1.5
4a4: Explain the concept of language ontologies, lexical
semantics and multilingualism. Session 7: Lab - Build a Legal-Person Ontology 3
B: Intellectual Skills Session 8_1: Ontology Modeling Challenges 1.5
4b1: Develop quality ontologies. Session 8_2: Stepwise Methodologies 1.5
4b2: Tackle ontology engineering challenges.
4b3: Develop multilingual ontologies. Session 9: Lab - Build a Legal-Person Ontology 3
4b4: Formulate quality glosses. Session 10: Zinnar – The Palestinian eGovernment 3
C: Professional and Practical Skills Interoperability Framework
4c1: Use ontology tools. Session 11: Lab- Using Zinnar in web services 3
4c2: (Re)use existing Language ontologies.
Session 12_1: Lexical Semantics and Multilingually 1.5
D: General and Transferable Skills
d1: Working with team. Session 12_2: WordNets 1.5
d2: Presenting and defending ideas. Session 13: ArabicOntology 3
d3: Use of creativity and innovation in problem solving.
Session 14: Lab-Using Linguistic Ontologies 3
d4: Develop communication skills and logical reasoning
abilities. Session 15: Lab-Using Linguistic Ontologies 3
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5. Outline and Session ILOs
This session will help students to:
4a2: Demonstrate knowledge of ontology engineering and evaluation.
4b2: Tackle ontology engineering challenges.
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6. Ontology Engineering Challenges
 Ontology Usability versus Ontology Reusability
 Ontology Application Dependence
• Only these challenges will be discussed, but there are many other
challenges that may face an ontology engineer.
• Discussing such challenges will help improve the modeling skills of
an ontology engineer.
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7. Ontology Reusability vs Usability
Given 4 different LegalPerson ontologies (which is more usable/reusable?)
O1
 Used by App1, 9000 times/day.
 Used by App1, 1000 times/day.
O2
 Used by App2, 1000 times/day.
 Used by App1, 100 times/day.
O3
 Used by App2, 100 times/day.
 Used by App3, 100 times/day.
 Used by App1, 10 times/day.
O4  Used by App2, 10 times/day.
 Used by App3, 10 times/day.
 Used by App4, 10000 times/day.
App1: Ministries’ Web Service to exchange companies’ profiles is based on this ontology.
App2: Champers of commerce’s Web Service to exchange companies’ profiles, based on this ontology.
App3: Banks designed their “new account” form, based on the company properties in this ontology (off time use).
App4: Lawyers refer to the definition of “company”, as stated in this ontology (off time use).
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8. Ontology Reusability vs Usability
Given 4 different LegalPerson ontologies (which is more usable/reusable?)
O1
 Used of different times/day.
Usability: maximizing the numberby App1, 9000 applications using
an ontology for the same kind of task.
 Used by App1, 1000 times/day.
Reusability: maximizing the number of different applications using
O2
 Used by App2, 1000 times/day.
an ontology over different kind of tasks.
Why Reusability:  Used by App1, 100 times/day.
1) Saving time, cost, and efforts…
O3
 Used by App2, 100 times/day.
2) Increasing reliability: the more reused the more tested.
3) An important quality  Used by App3, 100 times/day.
factor: a highly reusable ontology is an
indication that it is a good ontology.
 Used by App1, 10 times/day.
How to increase Usability? Used by App2, 10 times/day.

O4
by being closer to the application specifications and
requirements at hand.
 Used by App3, 10 times/day.

How to increase Reusability?Used by App4, 10 times/day.
App1: Ministries Web Service to exchange companies profiles is based on this ontology. i.e. be more
by taking into account different usages/applications,
App2: Champers of commerce’s Web Service to exchange companies profiles, based on this ontology.
general.
App3: Banks designed their “new account” form, based on the company properties in this ontology (off time use).
App4: Lawyers refer to the definition of “company”, as stated in this ontology (off time use).
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9. Ontology Reusability vs Usability
Given 4 different LegalPerson ontologies (which is more usable/reusable?)
O1
 Used of different times/day.
Usability: maximizing the numberby App1, 9000 applications using
an ontology for the same kind of task.
 Used by App1, 1000 times/day.
Reusability: maximizing the number of different applications using
O2
an ontology over Reusability Used by App2, 1000 times/day.
 Usability
different kind of tasks.
Why Reusability: usability and reusability 100 times/day.
Tradeoff between  Used by App1,
1) Savings in time, cost, and efforts…
O3
 Used by App2, 100 times/day.
2) The more an ontology is more reusedless more tested. be,
Increasing reliability: the usable the the reusable it will
3) and important quality  Used by App3, 100 times/day.
An vice versa. factor: a highly resalable ontology is an
 A good ontologyis a good ontology.
indication that it engineer knowsApp1, 10 times/day.
 Used by how/where to compromise
this tradeoff.
How to increase Usability? Used by App2, 10 times/day.

O4
by being closes to the application specifics and requirements at
hand.
 Used by App3, 10 times/day.

How to increase Reusability?Used by App4, 10 times/day.
App1: Ministries Web Service to exchange companies profiles is based on this ontology. i.e. be more
by taking into account different usages/applications,
App2: Champers of commerce’s Web Service to exchange companies profiles, based on this ontology.
general.
App3: Banks designed their “new account” form, based on the company properties in this ontology (off time use).
App4: Lawyers refer to the definition of “company”, as stated in this ontology (off time use).
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10. Ontology Application Dependence
Ontologies are supposed to capture knowledge at the domain level
independently of application requirements [G97] [GB99] [CJB99].
The problem is that when building an ontology, there will always be
intended or expected usability requirements -“at hand”- which influence
the independency level of ontology axioms.
This problem is as the Interaction Problem:
“Representing knowledge for the purpose of solving some
problem is strongly affected by the nature of the problem and
the inference strategy to be applied to the problem.”
Bylander and Chandrasekaran in [BC88]
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11. Ontology Application Dependence
What is the meaning of a “book” here?
Applications
Bookstores
?
Applications
Library
 Usability perspectives lead to different (and sometimes conflicting)
axiomatizations although these axiomatizations might agree at the domain level.
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12. Ontology Application Dependence
What is the meaning of a “book” here?
Applications
Bookstores
Both are not ontologies, they are data schemes.
? Can you build a useful and an application-independent ontology?
Applications
Library
 Usability perspectives lead to different (and sometimes conflicting)
axiomatizations although these axiomatizations might agree at the domain level.
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13. References
Mustafa Jarrar: Towards methodological principles for ontology engineering. PhD
Thesis. Vrije Universiteit Brussel. (May 2005)
Thomas R. Gruber: Toward Principles for the Design of Ontologies Used for Knowledge
Sharing http://tomgruber.org/writing/onto-design.pdf
Nicola Guarino: Formal Ontology and Information Systems http://www.loa-
cnr.it/Papers/FOIS98.pdf
Guarino, N.: Understanding, building, and using ontologies: A commentary to “Using
Explicit Ontologies in KBS Development”, by van Heijst, Schreiber, and Wielinga."
International Journal of Human and Computer Studies No. 46. (1997) pp. 293–310
[HV93] Hemmann, T., Voss, H.: A Reusable and Specializable Interpretation Model for
ModelBased Diagnosis. In: Luckenhoff, C., Fensel, D., Studer, D. (eds.): Proceeding
3rd KADS Meeting Siemens AG. Munich. March (1993) pp. 189–205
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