The Immediate Prospects for the Application of Ontologies in

Digital Libraries

Jody DeRidderSpring 2007

IS 565, Digital LibrariesDr. Suzie Allard, Professor

What are Ontologies?

Thesaurus: …. And MORE!!Parent Child Instance: Andy is a child. Sarah is a child. NT Father NT Daughter Relation: “fight” NT Mother NT Son Axiom: Sarah and Andy always fight. RT Child RT Parent Constraint: Until their parents stop them!

An ontology is like an expanded thesaurus.

Methods of encoding our concepts and their relationships so computers can understand us, and help us find what we need.

Ontology components (constructs)

concepts (and their properties) instances (examples of concepts) relations axioms (always true) constraints (only true if)

Wine

Beringer White Zinfandel

GrapesZinfandel Grapes

Type of

Mad

e Fr

om

BUT!!Only when produced by

Beringer Corp.

White ZinfandelType ofProduces

Alw

aysA

lways

Made F

rom

Type of

Mad

e Fr

om

Lightweight Ontologies: are little more than taxonomies, and include: concepts, properties that describe concepts, and relationships. An example of this would be Dublin Corehttp://www.cs.umd.edu/projects/plus/SHOE/onts/dublin.html

Heavyweight ontologies: also include axioms and logic constraints An example of this would be Cyc http://

www.cyc.com/cyc/technology/whatiscyc.

Ontology Types: Depth of Territory

The more heavyweight the ontology is, the more expressive and powerful – and the more complex and costly to create, implement, and maintain.

Global Ontologies

Domain Ontologies

Application Ontologies

Ontology Types: Breadth of Territory

Simpler for computer applications if we can all map to a single global ontology – but MUCH more difficult for humans to agree on, implement, and maintain.

Botany Art History

Creating Lesson Plans

Identifying DiseasesBy Symptomology

An Audio Tape Ontology Example

http://jodi.tamu.edu/Articles/v01/i08/Hunter/

An example use of an ontology in education…

Alexandria Digital Earth Prototypehttp://www.alexandria.ucsb.edu/research/learning/index.htm

http://onto.stanford.edu:8080/wino/index.jsp -- where you can select a food and the software will choose appropriate

wines to accompany your meal.

An example you can play with: Wine Agent 1.0

How does it work?

If seafood is tagged as having the property of requiring a dry white wine; and swordfish is listed as an instance (type) of seafood; and a certain Swiss Chardonnay has been added as an instance (type) of dry white wine–

then when you ask what wine to serve with swordfish, this Chardonnay would be suggested to accompany your dinner.

Ontology Mapping

So… we all speak different “languages” or ontologies; to support searching across the variation of terms, we need to map each ontology onto the others… a form of translation.

One such ontology mapping language is XeOml, which allows one-to-one or one-to-many mappings between elements of two ontologies.

From: http://dit.unitn.it/~bouquet/ISWC-04-MCN/papers/10-Pazienza.pdf

Harebell

Downiniga elegans

showy downinig

a

Purple flower

Problems in Ontology Mapping

Michael Klein, 2001. <http://www.informatik.uni-bremen.de/agki/www/buster/IJCAIwp/Finals/klein.pdf>

How do query engines use ontology mapping?An example from OBSERVER

[Mena, 2000]

Standards, the bottom line for interoperability

To represent knowledge so that computers can “understand” us, we need to use formats they can process, and a language they can understand.

For applications to be interoperable, we need agreed-upon standards:

Resource Description Framework (RDF) is a simple notation for representing relationships between and among concepts. Each concept is represented by a URL.

Web Ontology Language (OWL) is a more complex artificial language for the exact description of things and their relationships.

RDF: Resource Description Framework

<?xml version="1.0"?><rdf:RDF xmlns:rdf= "http://www.w3.org/1999/02/22-rdf-syntax-ns#" xmlns:contact= "http://www.w3.org/2000/10/swap/pim/contact#"> <contact:Personcontact:Person rrdf:about="http://www.w3.org/People/EM/contact#me"> <contact:fullName> Eric Miller</contact:fullName> <contact:mailbox rdf:resource="mailto:em@w3.org"/> <contact:personalTitle>Dr.</contact:personalTitle> </contact:Person></rdf:RDF>

From: http://www.w3.org/TR/REC-rdf-syntax/

Subject: Contact Person

Predicate: fullName

Object: Eric Miller

Example: RDF/XML Describing Eric Miller

OWL: Web Ontology Language

OWL and RDF have similarities, but OWL is a much stronger language with greater machine interpretability than RDF.

Three Sublanguages:

* OWL Lite Hierarchical Classification, simple constraints.

* OWL DL Description Logic: as expressive as is possible while maintaining

the logic needed for computers to reason and make inferences.

* OWL Full Maximum expressiveness with no computational guarantees.

Think of this OWL and RDF as frameworks for concepts and their possible relations.

You use the framework to encode the Ontology.

Ontologies… who needs them?

Findability Query Expansion Reasoning

…to help us sift through the exponential growth of digital materials

We do!!!

Ontology Implementation Tasks

Simperl and Tempich, 2006 <http://ontocom.ag-nbi.de/docs/odbase2006.pdf>>

What are the costs?

• Product factors complexity of the domain analysis, conceptualization, implementation,

instantiation, evaluation, integration, reusability, and documentation

• Personnel factors ontologist/domain expert capability & experience, language and tool experience, and personnel continuity

• Project factors tool support, multi-site development, required development schedule

• Reuse/maintenance factors ontology understandability, domain/expert unfamiliarity, complexity of

evaluation, modifications, and translations

ONTOCOM: http://ontocom.ag-nbi.de/index.html

How complex is your ontology? Heavyweight or lightweight?

And how broad is your domain?

Where are ontologies most feasible?

Commercial Ventures and Commercially Funded Research Example: Xyleme http://www.reddogsoftware.com/page/xyleme/

Government (especially Defense) Example: Ontology Works http://www.ontologyworks.com/

Possibly Education?If you work in one of these areas,

*you* will likely be using ontologies!

For the rest of us…

If you are in a general purpose digital library, and you have the funding:• start the research (what is your target audience’s terminology, versus the terminology of your content descriptions?) • watch the tools develop, and test them• watch for domain and global ontologies that are given the W3C stamp of approval! . . . IT WON’T BE LONG NOW!

Until the development, application, and maintenance becomes cheaper and easier, ontologies will not be feasible for general purpose digital libraries without major ongoing funding.

Bibliography

• Simperl, Elena Paslaru Bontas and Christoph Tempich. “Ontology Engineering: a Reality Check.”

• 5th International Conference on Ontologies, Databases, and Applications of Semantics, 2006.

• <http://ontocom.ag-nbi.de/docs/odbase2006.pdf> (16 March 2007).

Bontas, Elena Paslaru and Malgorzata Mochol. “Ontology Engineering Cost Estimation with ONTOCOM.” Technical Report TR-B-06-01, Freie Universität Berlin, Germany, 7 February 2006. <http://ontocom.ag-nbi.de/docs/tr-b-06-01.pdf> (16 March 2007).

Data, Refnes. "Introduction to OWL.” W3Schools, 2006. <http://www.w3schools.com/rdf/rdf_owl.asp> (1 April 2007).

de Bruijn, Jos. “Using Ontologies: Enabling Knowledge Sharing and Reuse on the Semantic Web.” Digital Enterprise Research Institute Technical Report DERI-2003-10-29, October 2003. <http://www.deri.at/fileadmin/documents/DERI-TR-2003-10-29.pdf> (13 March 2007).

Doerr, Martin, Jane Hunter, and Carl Lagoze. “Towards a Core Ontology for Information Integration.” Journal of Digital Information, 4:1, Article 169, 9 April 2003. <http://jodi.ecs.soton.ac.uk/Articles/v04/i01/Doerr/> (3 February 2007).

Hsu, Eric L. “Wine Agent: How does it work?” Stanford University Knowledge Systems

Artificial Intelligence Laboratory , 8 April 2003. <http://www.ksl.stanford.edu/projects/wine/explanation.html> (3 February 2007).

Hunter, Jane. “MetaNet – A Metadata Term Thesaurus to Enable Semantic Interoperability Between Metadata Domains.” Journal of Digital Information, 1:8, No. 42, 8 February 2001. <http://jodi.tamu.edu/Articles/v01/i08/Hunter/> (24 February 2007).

Institut für Informatik. “ONTOCOM Cost Drivers.” Institut für Informatik, Networked Information Systems, Freie Universität Berlin, 2006. <http://ontocom.ag-nbi.de/ontocom.html> (1 April 2007).

Bibliography, continuedInternational Conference on Ontologies, Databases, and Applications of Semantics, 2006. <http://ontocom.ag-nbi.de/docs/odbase2006.pdf> (16 March 2007).

Klein, Michael. “Combining and Relating Ontologies: An Analysis of Problems and Solutions.” International Joint Conferences on Artificial Intelligence Workshop on Ontologies and Information Sharing, 2001. <http://www.informatik.uni-bremen.de/agki/www/buster/IJCAIwp/Finals/klein.pdf> (13 March 2007).

Mena, Eduardo, et. al. “OBSERVER: An Approach for Query Processing in Global Information Systems Based on Interoperation Across Pre-Existing Ontologies.” Distributed and Parallel Databases, 8, 223- 271, 2000.

Menzies, Tim. “Cost Benefits of Ontologies.” Intelligence, Fall 1999. Copyright 1997 Don Bishop, Artville, LLC.

Milam, John. “Ontologies in Higher Education.” HigherEd.org, 2005. <http://highered.org/docs/milam-ontology.pdf> (1 April 2007)

Ontology Works, Inc. “Ontology Works Knowledge Server.” 2005. <http://www.ontologyworks.com/ks.php> (18 March 2007).

Pazienza, Maria Teresa, et. al. “XeOML: An XML-based extensible Ontology Mapping Language.” Paper presented at the 3rd International Semantic Web Conference (ISWC2004) in Hiroshima, Japan, November 2004. <http://ai-nlp.info.uniroma2.it/stellato/publications/2004_ISWC-04_XeOML%20An%20XML-based%20extensible%20Ontology%20Mapping%20Language.pdf> (6 February 2007).

Bibliography, continuedShreve, Gregory M. and Marcia Lei Zeng. “Integrating Resource Metadata and Domain Markup in an NSDL Collection.” In Proceedings of the International DCMI Metadata Conference and Workshop, Seattle, WA, 28 September - 2 October, 2003. <http://www.siderean.com/dc2003/604_paper62.pdf> (16 March 2007).

Simperl, Elena Paslaru Bontas and Christoph Tempich. “Ontology Engineering: a Reality Check.” 5th International Conference on Ontologies, Databases, and Applications of Semantics, 2006.

<http://ontocom.ag-nbi.de/docs/odbase2006.pdf> (16 March 2007).

Smith, Terence R., Marcia L. Zeng, and the ADEPT project Team. “Building Semantic Tools for Concept- based Learning Spaces: Knowledge Bases of Strongly- Structured Models for Scientific Concepts in Advanced Digital Libraries.” Journal of Digital Information, 4:4, Art. 263, 28 January 2004. <http://jodi.tamu.edu/Articles/v04/i04/Smith/> (16 March 2007).

Sourceforge. “Ontology MApping FRAmework (MAFRA) Toolkit.” Open Source Technology Group, 31 January 2007. <http://mafra-toolkit.sourceforge.net> (18 March 2007).

Stuckenschmidt, Heiner, and Frank van Harmelen. Information Sharing on the Semantic Web. Berlin: Springer, 2005.

Welty, Chris. “Ontology Maintenance Support: Text, Tools, and Theories.” Presentation at the 7th International Protégé Conference, Bethesda MD, 2004. <

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World Wide Web Consortium. “OWL Web Ontology Language Guide.” W3C Recommendation, February 2004. <http://www.w3.org/TR/owl-guide/> (26 March 2006).

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