State of the Art Paper The Foundation for Semantic Interoperability on the World Wide Web

....................................................................................................................... 5 OVERVIEW ....................................................................................................................... 6 1. INTEROPERABILITY IN INFORMATION SYSTEMS.......................................................... 10 1.1 Definition............................................................................................................. 10 1.2 Approach to achieve interoperability.................................................................. 11 1.2.1 Standards ...................................................................................................... 11 1.2.2 Layered approach ......................................................................................... 11 1.2.3 Mediators...................................................................................................... 12 1.2.4 Wrappers ...................................................................................................... 13 1.3 Toward semantic interoperability in information systems.................................. 13 2. SEMANTICS AND ITS REPRESENTATION....................................................................... 15 2.1 Semantics............................................................................................................. 15 2.1.1 Definition ..................................................................................................... 15 2.1.2 Declarative semantics vs. Procedural semantics .......................................... 15 2.1.3 Intension vs. Extension ................................................................................ 16 2.2 Knowledge Representation.................................................................................. 17 2.2.1 Definition ..................................................................................................... 17 2.2.2 Logic and computation................................................................................. 18 2.2.3 Ontology....................................................................................................... 21 2.2.4 Approaches in representing knowledge ....................................................... 22 A. Frame-based systems.................................................................................... 22 B. Semantic Networks....................................................................................... 22 C. KL-ONE ....................................................................................................... 25 D. Description Logic ......................................................................................... 28 E. Nonmonotonic Reasoning: KR under uncertainty........................................ 30 3. INTEROPERABILITY ON THE WEB................................................................................ 33 3.1 Markup Languages.............................................................................................. 33 3.2 Hypertext Markup Language (HTML) ................................................................ 35 3.3 Extensible Markup Language (XML).................................................................. 37 3.3.1 XML Document ........................................................................................... 38 3.3.2 XML as a Data Interchange Format for the Web......................................... 41 3.3.3 XML Schema ............................................................................................... 42 4. WEB SEMANTICS........................................................................................................ 45 4.1 Metadata.............................................................................................................. 45 4.1.1 Definitions.................................................................................................... 45 4.1.2 Dublin Core .................................................................................................. 45 4.1.3 Warwick Framework.................................................................................... 47 4.1.4 Resource Description Framework (RDF) .................................................... 50 A. RDF Design Goals........................................................................................ 50 B. RDF Data Model .......................................................................................... 53 C. RDF Syntax .................................................................................................. 56 D. RDF Schema................................................................................................. 57 4.1.5 Topic Maps................................................................................................... 59 4.2 Semantic Web ...................................................................................................... 61