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. Separation of Content from Presentation
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
1st generation, Internet enabled disparate machines to exchange data
2nd 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. Semantics remain Under-Specified
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
<rdf:RDF  xmlns:rdf="  xmlns:s="  
  <rdf:Bag ID="B1">       <rdf:li>       <s:resourceAccessRule rdf:ID="U2" s:access="get,put,delete">                  <s:accessor rdf:resource="               </s:resourceAccessRule></rdf:li>    </rdf:Bag>    <rdf:Description aboutEach="#B1">       <s:hasAccessTo rdf:resource="    </rdf:Description>
</rdf:RDF>

9. RDFS Example
<rdfs:Class ID="ResourceAccessRule">   <rdfs:label xml:lang="en">Access Rule</rdfs:label>   <rdfs:comment>An assertion of access privileges to a resource.</rdfs:comment>   <rdfs:isDefinedBy resource=" </rdfs:Class>
<rdf:Property ID="hasAccessTo">   <rdfs:label xml:lang="en">has access to</rdfs:label>   <rdfs:comment>Relates an Access Rule to the resources to which the rule applies.  The inverse relation is 'accessedBy'</rdfs:comment>   <rdfs:range rdf:resource="   <rdfs:domain rdf:resource="#ResourceAccessRule"/>   <rdfs:isDefinedBy resource=" </rdf:Property>

10. More Semantically Rich
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 <rdf:Property ID="memberOf"> <rdf:type
rdf:resource=" standard#TransitiveProperty"/>   <rdfs:label xml:lang="en">member of</rdfs:label>   <rdfs:comment>The relationship of a member of a group to that group.</rdfs:comment>   <rdfs:range rdf:resource="#Group"/>   <rdfs:domain rdf:resource="#Principle"/>   <rdfs:isDefinedBy resource=" </rdf:Property>

13. Semantic Web Logic Proof Trust
I am an employee of UMBC. UMBC is a member of W3C. UMBC has GET access to I (therefore) have access to
Proof
UMBC's document employList lists me as an employee. W3C'c member list includes UMBC. The ACLs for assert that employees of members have GET access.
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 were set by an agent trusted by the access control mechanism.
Making the simple stuff simple and the complex stuff possible.