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Semantic Web Thanks to folks at LAIT lab Sources include : Tim Berners-Lee Presentation W3C Semantic Web Activity Presentation of W3C and Semantic Web.

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Presentation on theme: "Semantic Web Thanks to folks at LAIT lab Sources include : Tim Berners-Lee Presentation W3C Semantic Web Activity Presentation of W3C and Semantic Web."— Presentation transcript:

1 Semantic Web Thanks to folks at LAIT lab Sources include : Tim Berners-Lee Presentation W3C Semantic Web Activity Presentation of W3C and Semantic Web by Eric Prudhommeaus

2 What is XML HTML describes document structure and presentation XML is meta-language used to define other domain or industry specific language XML addresses “structuring” of data rather than documents XML documents by themselves, bear no semantics Separation of Content from Presentation

3 XML and Semantics XML Documents do not have semantics One uses XML to define an XML language adhering to a particular DTD XML documents can have semantics only by convention Implicit Semantic agreement on paper within a community of users for a particular domain data

4 Semantic Web 1 st generation, Internet enabled disparate machines to exchange data 2 nd generation, enabled new applications on top of growing internet, making enormous amounts of information available, in human-readable form, and allowing revolution in new applications B2C The next generation of the net is an “agent- enabled” (Semantic Web) which makes information available in machine-readable form …. enabling “agent” communication at a Web-wide scale

5 Semantic Web The Semantic Web is a vision: the idea of having data on the web defined and linked in a way that it can be used by machines The Semantic Web approach proposes languages for expressing information and the relationships between information. … Over time, these languages will accommodate additional formal systems techniques for verification of logical consistency and for reasoning” - W3C Semantic Web Activity Statement

6 Tim Berners- Lee’s Vision of Semantic Web

7 RDF & RDFS Provide a data model and syntax convention for representing the semantics of data in standardized interoperable manner Describe relationships among resources as “subject-verb-object” triples and properties & values RDFS – Minimal ontology modeling language, object oriented type system Semantics remain Under-Specified

8 RDF Example

9 RDFS Example Access Rule An assertion of access privileges to a resource. has access to Relates an Access Rule to the resources to which the rule applies. The inverse relation is 'accessedBy'

10 Ontology Layer A common vocabulary an agreed upon meanings to describe a subject domain Widens interoperability & inter-conversion More meta-information such as –Transitive property –Unique, unambiguous, cardinality etc. More Semantically Rich

11 DAML + OIL Goal to define language(s) for the Semantic Web Build on top of RDF and XML Adds more constraints to RDF Allows definition, sharing, composition and use of ontologies Frame based knowledge representation language Add meta-data about anything which has URI

12 DAML+OIL Example member of The relationship of a member of a group to that group.

13 Semantic Web Logic –I am an employee of UMBC. UMBC is a member of W3C. UMBC has GET access to http://www.w3.org/Member/. I (therefore) have access to http://www.w3.org/Member/.http://www.w3.org/Member/ Proof –UMBC's document employList lists me as an employee. W3C'c member list includes UMBC. The ACLs for http://www.w3.org/Member/ assert that employees of members have GET access.http://www.w3.org/Member/ Trust –UMBC's document employList is signed by a private key that W3C trusts to make such assertions. W3C'c member list is trusted by the access control mechansim. The ACLs for http://www.w3.org/Member/ were set by an agent trusted by the access control mechanism.http://www.w3.org/Member/ Making the simple stuff simple and the complex stuff possible.


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