Transcript The Immediate Prospects for the Application of Ontologies in Digital Libraries Jody DeRidder Spring 2007 IS 565, Digital Libraries Dr.

The Immediate Prospects for the
Application of Ontologies in
Digital Libraries
Jody DeRidder
Spring 2007
IS 565, Digital Libraries
Dr. Suzie Allard, Professor
What are Ontologies?
Methods of encoding our concepts and their
relationships so computers can understand us, and
help us find what we need.
An ontology is like an expanded thesaurus.
Thesaurus:
Parent
NT Father
NT Mother
RT Child
Child
NT Daughter
NT Son
RT Parent
…. And MORE!!
Instance: Andy is a child. Sarah is a child.
Relation: “fight”
Axiom: Sarah and Andy always fight.
Constraint: Until their parents stop them!
Ontology components (constructs)





Beringer
Corp.
concepts
instances
relations
axioms
constraints
Produces
(and their properties)
(examples of concepts)
(always true)
(only true if)
Beringer White Zinfandel Type of
White Zinfandel
BUT!!
Only when produced by
Wine
Zinfandel Grapes Type of
Grapes
Ontology Types: Depth of Territory
Lightweight Ontologies:
are little more than taxonomies, and include:
 concepts,
 properties that describe concepts, and
 relationships.
An example of this would be Dublin Core
http://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.
The more heavyweight the ontology is, the more expressive and powerful –
and the more complex and costly to create, implement, and maintain.
Ontology Types: Breadth of Territory
Global Ontologies
Domain Ontologies
Botany
Art
History
Application Ontologies
Creating Lesson
Plans
Identifying Diseases
By Symptomology
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.
An Audio Tape Ontology Example
http://jodi.tamu.edu/Articles/v01/i08/Hunter/
An example use of an ontology in
education…
Alexandria Digital Earth Prototype
http://www.alexandria.ucsb.edu/research/learning/index.htm
An example you can play with: Wine Agent 1.0
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. 
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.
Harebell
Downiniga
elegans
showy
downinig
a
Purple
flower
From: http://dit.unitn.it/~bouquet/ISWC-04-MCN/papers/10-Pazienza.pdf
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"?>
Example: RDF/XML Describing Eric Miller
<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:Person rdf:about="http://www.w3.org/People/EM/contact#me">
<contact:fullName> Eric Miller</contact:fullName>
<contact:mailbox
rdf:resource="mailto:[email protected]"/>
<contact:personalTitle>Dr.</contact:personalTitle>
</contact:Person>
</rdf:RDF>
Subject: Contact Person
Predicate: fullName
Object: Eric Miller
From: http://www.w3.org/TR/REC-rdf-syntax/
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?
We do!!!
Findability
Query Expansion
Reasoning
…to help us sift through the exponential growth
of digital materials
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…
Until the development, application, and
maintenance becomes cheaper and easier,
ontologies will not be feasible for general
purpose digital libraries without major ongoing
funding.
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!
Bibliography
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.”
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<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
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Bibliography, continued
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Mena, Eduardo, et. al. “OBSERVER: An Approach for Query Processing in Global Information Systems
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Bibliography, continued
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