Semantic Web Lecture, Summer 2004, University of Hannover A course on the Semantic Web given at University of Hannover by Prof. Dr. N. Henze N. Henze 2004-10-04 Internet and World Wide Web Internet World Wide Web W3C - World Wide Web Consortium W3C - Recommendations Other Standards: RFCs: Request for Comments Semantic Web : What do we need a Semantic Web for? Todays Web Techniques Ways to improve the current web Semantic Web: What should be achieved? Semantic Web: How can machines better recognize and process content? Definitions of Semantic Web Definition of T. Berners-Lee Definition of the Semantic Web Activity Group @ W3C Semantic Web Tower Markup languages and Meta languages SGML: Standard Generalized Markup Language SGML: Standard Generalized Markup Language HTML - Hypetext Markup Language Structure of HTML documents HTML Head: Meta information Structuring text with HTML HTML - Links XML - Extensible Markup Language XML - Prolog XML - Elements XML - Attributes XML - Comments XML - Processing instruction Well-formed XML Valid XML XMl - Document Type Definition Elements Attributes XML Schema XML Schema: Element types XML Schema: Attribute Types Types in XML Schema Extending Data Types Restricting Data Types Restricting Data Types The problem The solution Namespace Syntax XHTML XHTML 1.0 vs. HTML 4.0 XHTML 1.1 Module-based XHTML Friends and members of the XML Family CSS - Cascading StyleSheets Internal CSS External CSS Pseudo Classes in CSS XPATH Locating Nodes in XPATH Selecting Branches Selecting Several Paths Selecting Attributes Location Path Expression Axes And Node Tests Axes Node-Tests Predicates Location Path Abbreviated Syntax Numerical Expressions Equality Expressions Testing Against a Node-Set Relational Expressions Boolean Expressions XPath Function Library String Functions Number Functions Boolean Functions XSL: Extensible Style Sheet Language Whats with stylesheets in the first place? What Does a Stylesheet Do? Transformation capabilities Description of information The components of the XSL language XML to result tree Result tree doctypes An XSL stylesheet The Structure of a Stylesheet Stylesheet Examples A Complete Example Understanding A Template Example XML - File Conflict Resolution Applying Style Procedurally For-each Example Creating the Result Tree Conditional Processing Numbering Sorting Sorting Example Formatting objects and properties Sample FO result tree Some XSL-FO templates Formatting Object Basics Common Formatting Objects Basic properties Overall XSL formatting capabilities Chapter, title, para example Some XSLT-Processor FOP RDF: Resource Description Framework Basic Building Blocks Basic Building Blocks Basic Building Blocks Resources Statements Three views of a statement Reification Data Types in RDF RDF: Discussion and Critiques Semantic Web Tower RDF: XML based syntax rdf:resource Nested Descriptions rdf:Type Container Elements RDF: Collections Reification RDF Schema(RDFS) RDFS: Purpose Classes and properties Class hierarchies Comparison to Object-Oriented Programming Property Hierarchies The RDF Schema Language RDFS: Core Classes RDFS: Core Properties RDFS: Restricting Properties Properties for Reification Container Utility Properties OWL - Web Ontology Language OWL in OWL Some thoughts about the future of OWL Intorduction to Ontology Engineering steps to create an Ontology Determine the domain and scope of the ontology Consider reusing existing ontologies Enumerate important terms in the ontology Define the classes and the class hierarchy Define the properties of classes Define Facets Create Instances! Check for Anomalies Logical Languages Boolesche Logik / Propositional Logik Wahrheitstabelle fur Boolesche Logik First Order Logic (FOL) Description Logic (DL) Rule Systems (Horn Logic, definite logic programs) Rules Facts Logic Programs Goals Rule Markup Rule Markup in XML.. Monotonic Rules Terms Atomic Formulas Facts Rules Queries DTD for monotonic rules Rule Markup in XML.. Monotonic Rules DTD Proof, Trust and Security Trust and Policy Management Goals for Trust and Policy Management Interaction dimensions between autonomous communicating parties Example A trust framework for simple data transfer Example of an extended transaction Current Initiatives with participation of University of Hannover Web Services The User Factor- Personilization for the Semantic Web Adaptive Hypermedia Adaptive Hypermedia Modeling a User What can be in a User Model Adaptation for Hypertext Personalization Techniques Adaptive Hypermedia ALogic-Based Definition of Adaptive Simple: A Simple Adaptive Hypermedia System A simple AEHS - Extension 1 A simple AEHS - Extension 2 Recommendation Techniques Overview of recommendation techniques Content-based recommendations Collaborative recommendations / social information filtering Demographic recommendations Utility-based recommendations Knowledge-based recommendations