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Ontology-based User Modeling for Web-based Information Systems Anton Andrejko, Michal Barla and Mária Bieliková {andrejko, barla, bielik}@fiit.stuba.sk
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ISD 2006Ontology-based User Modeling for Web-based Information Systems 2 Web-based IS and User Modeling Motivation: –Users with different knowledge and needs –Exponential growth of information on the Web People are overloaded with information Finding relevant information can be nearly impossible Solution: Focus on individual user and her needs Personalization of content-oriented web-based IS
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ISD 2006Ontology-based User Modeling for Web-based Information Systems 3 Adaptation Process Peter Brusilovsky: Methods and techniques of adaptive hypermedia. User Modeling and User-Adapted Interaction, 6(2-3):87–129, 1996.
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ISD 2006Ontology-based User Modeling for Web-based Information Systems 4 User Model Beliefs about the user that include preferences, knowledge and attributes (characteristics) for a particular domain Used to adapt the content, presentation or navigation –Filtering on behalf of the user –Interpretation of the users input –Personalization of systems output
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ISD 2006Ontology-based User Modeling for Web-based Information Systems 5 Presentation Overview Overview of various representation of user model Example of incorporation of a model into IS architecture Example of an ontology-based user model –Used at the project Tools for Acquiring, Organizing and Presenting Information and Knowledge in an Environment of Heterogeneous Information Sources –http://nazou.fiit.stuba.skhttp://nazou.fiit.stuba.sk
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ISD 2006Ontology-based User Modeling for Web-based Information Systems 6 User Model Representations Relational database –User Model represented as a set of interconnected tables –Characteristic = attribute in the relational data model XML-based language –Characteristics represented as values or attributes of specific tags personal.name John Smith false
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ISD 2006Ontology-based User Modeling for Web-based Information Systems 7 User Model Representations Ontology-based representation –Ontology ~ an explicit specification of the conceptualization of a domain –Using RDF/OWL formalisms Define classes and properties Define a vocabulary for describing classes and properties
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ISD 2006Ontology-based User Modeling for Web-based Information Systems 8 Flexibility, changeability Uniform representation for different kinds of characteristics Relational database - –User model created as an overlay of a domain model –User model contains semi-structured data –Changing the structure of tables brings often problems XML - Ontology -
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ISD 2006Ontology-based User Modeling for Web-based Information Systems 9 Performance Relational database – –Good theoretical background –Maturity of DBMS XML – –limited by performance of used file system or XML database Ontology – –immature technologies
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ISD 2006Ontology-based User Modeling for Web-based Information Systems 10 Reasoning Relational database, XML – –No formally defined semantics Ontology – –Relations, conditions and restrictions provide the basis for inferring additional user characteristics
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ISD 2006Ontology-based User Modeling for Web-based Information Systems 11 Easy of use Relational database - –Most of content-oriented IS already use some rel. DB –Mature technology XML - –Many tools available –Mature technology Ontology - –Lack of experts, tools –Immature technology
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ISD 2006Ontology-based User Modeling for Web-based Information Systems 12 Understandability Can domain expert work easily with a model? Relational database - –Relational calculus can be hard to understand (M:N) XML - Ontology - –Thinking in terms of classes, instances, relations and restrictions is close to thinking of an expert We need a visualization for complicated models!
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ISD 2006Ontology-based User Modeling for Web-based Information Systems 13 Shareability and reusability Shareability – needed for the Semantic Web vision Relational database - –Proprietary, platform-dependent XML – –Platform independent –Everyone can invent his own names for tags Ontology – –Easy combining of existing models into the new ones Creation of an overlay model is intuitive
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ISD 2006Ontology-based User Modeling for Web-based Information Systems 14 User model in web-based IS Web-based IS for people looking for a job Offers are retrieved from the Web and processed into ontological representation (domain model) User is adaptively navigated to offers of her interest Various presentation tools integrated in portal solution
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ISD 2006Ontology-based User Modeling for Web-based Information Systems 15 Web-based IS using User Model Standard layered architecture –Presentation layer Personalized presentation layer Click SemanticLog LogAnalyzer Factic TopK
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ISD 2006Ontology-based User Modeling for Web-based Information Systems 16 User Model User model consists of two parts –Domain-dependent Use the same vocabulary as a domain model –Domain-independent Describe user as a person
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ISD 2006Ontology-based User Modeling for Web-based Information Systems 17 Domain independent part
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ISD 2006Ontology-based User Modeling for Web-based Information Systems 18 Domain model
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ISD 2006Ontology-based User Modeling for Web-based Information Systems 19 Domain dependent part
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ISD 2006Ontology-based User Modeling for Web-based Information Systems 20 Conclusions Web-based IS Adaptive Web-based IS User model is necessary for adaptation Relational representation of a model does not fulfill our needs Ontological representation of a model Semantic Web vision opens data to the world Sharing aspect is becoming more important More information about the project: –http://nazou.fiit.stuba.skhttp://nazou.fiit.stuba.sk
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