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Semantic Web: Annotating course material with metadata

Semantic Web: Annotating course material with metadata. Ontology-Development and Application Example: MIT OPEN COURSEWARE Martina Brose & Gebhard Dettmar for HS Knowledge and the Web. Need for Information Retrieval in scientific communities.

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Semantic Web: Annotating course material with metadata

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  1. Semantic Web: Annotating course material with metadata Ontology-Development and Application Example: MIT OPEN COURSEWARE Martina Brose & Gebhard Dettmar for HS Knowledge and the Web

  2. Need for Information Retrieval in scientific communities • Faculties often make use of the www to present course material. Sometimes they use access limitations • In a scientific network these limitations are overcome. The aim ist to represent as much material as possible in the most accessable way to anyone who needs the Information these materials provide • Companies do the same in TCP/IP driven Intranets

  3. Example MIT OCW (Open Course Ware) • „the goal is to provide the course materials free and open to the world.“ (FAQ 6) „and (to) create a global web of knowledge“ (a message from the president) • providing the world with Information („adding logic to the web“) requires a world-wide valid concept that comes from an AI-Field: knowledge-representation. MIT´s goal is to fulfill the needs of such concepts by 2007. In the moment it´s just plain html.

  4. XML is called a „Meta-Language“ lets you define your own tags allows for arbitrary structure still says nothing about the meaning of a structure RDF Schema comes frome the AI-Discipline Knowledge Represantation and is (by surprise) expressable in XML carries meaning by using triples (subject, predicate, object) subject and object are identified via URIs. A resource (subject) is described by a property (predicate), this property has a value (object) Two ways of „Adding logic to the web“(Tim Berners-Lee)XML and RDF Big problem

  5. The next steps: DAML+OIL; OWL • The next step in developing the semantic web is DAML. DAMLis the first `expressis verbis´ ontology and inference language based upon RDF1. • „DAML+OIL divides the world up into objects, which are elements of DAML classes, and datatype values...“2 • In DAML you can use the UnambigiousProperty class, which says that if two subjects have a common object, these subjects are equivalent. 1cf. http://infomesh.net/2001/swintro/ 2 cf http://www.daml.org/2001/03/daml+oil-walkthru

  6. XML Schema, RDFS, DAML+OIL, OWL – quot homines, tot linguae. An overview:

  7. MIT Course `Industrial Organization´ • IO consists of Introduction, Time Schedule, Problem Sets, an Exam, a Reading List, related Links and gives some preliminary documents like „Monopoly Pricing“

  8. Considerations for „Industrial Organization“-Ontolgy • Ind. Org. is a subclass of EconomicsCourse. It has all properties of this class, i.e URL, staff, docs, description, term etc. Economics is a subclass of „course“ • course is the object of its subclasses „economy“ and „biology“, so they are equivalent (UnambigiousProperty, see below) • They have properties (e.g. ofScience) that link them and give them values (over domains and ranges, see below)

  9. RDF Model for MIT Course `Industrial Organization´1 http://ocw.mit.edu/14/14.271/f01/pdf/industr.pdf http://../14/14.271/f01/index.html hasDocument hasURL hasTitle Industrial Organization isAuthorOf http://ocw.mit.edu/global/department14.html Sara Ellison Glenn Ellison Olivier Blanchard1 hasName http://ocw.mit.edu/#person isOfScience isPerson hasURL Economics hasStaff http://ocw.mit.edu/#Staff 1cf. MIT-Ontology in OWL from Martina Note that the verbs (syntactically speaking: predicates) also get URIs 1 simplification: of course each predicate has its own value

  10. The main concept behind RDF(S): the statement • The diagramm (slide 9) shows what in RDF Schema is called a statement. A statement always consists of a triple. It defines the value of a property of a resource. • Everything that is expressed in RDF(S) is expressed in this triple: subject, predicate, object • It is possible to make a statement a resource (Reification) Doing so we are able to make statements about statements. E.g. it is possible to say: the statement „Glenn Ellison (subject) is member (predicate) of http://ocw.mit.edu/#Staff (object)“ is only valid for a certain time but not generally true. • This ability is the core-component of the Semantic Web

  11. Domains and Ranges – to which classes does a property belong? • Industrial Organization isOfScience economics1 reads that this property „ofScience“ has a subject (Industrial Organization) of a domain „course“ and an object (Economics) of a range „science“ • So the subject is an Individual of the class „course“ and the object of the class „science“ • You will see that in Martinas code in detail 1cf. slide 9

  12. Practical work • like I said before MIT is quite vague about their approach to semantics. In the end they tell nothing more than „metadata is important“. Technological aims concern Content Management rather than ontologies. • Martina did their job. She made up her mind to see how an OCW-Ontology should look like • Now see what she did click here for Martinas Presentation

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