Introduction to the Semantic Web

1. What is the Semantic Web?
 : an extension of the current Web in which information is given a well-defined meaning, better enabling computers and people to work in cooperation.

 - The annotated Web
  1) Enrich existing web pages with annotations
  2) Annotations enable enhanced browsing and searching

 - The Web of Data
  1) Expose existing databases in a common format: it allows the integration of data in unexpected ways
  2) Express existing database schemas in a machine-understandable form: it allows reasoning about data

https://www.w3.org/standards/semanticweb/


2. The Origins of the Semantic Web
 - Interwoven themes: Knowledge Based Systems + Hypertext/Hypermedia + Library and Information Science
  1) Knowledge representation 
   * Long-standing discipline within Artificial Intelligence
   * Knowledge representation languages should handle qualitative knowledge
     e.g. RDF, RDF Schema and OWL
  2) Hypertext/Hypermedia
   * Links: essence of hypermedia is connection
   * Open hypermedia makes links between different bits of knowledge but Network knowledge representation makes links that are knowledge
  3) Library and Information Science
   * Library cataloguing = metadata
   * Metadata: data about data

http://artint.info/html/ArtInt_8.html


3. Basic Concepts

The World Wide Web	The Semantic Web
the web for people	the web for machines
machine readable: information needs humans to give it interpretation	machine understandable: information is structured so that it can be interpreted by machines
technologies include URI, HTTP, XML and HTML	technologies include RDF, RDFS and OWL

4. Semantic Web Technical Architecture
 - Fundamental Principles
  1) Anyone can make assertions about anything
  2) Entities are referred to using Uniform Resource Identifiers
  3) Based on XML technologies
  4) Formal Semantics

 - The Semantic Web layer cake: https://en.wikipedia.org/wiki/Semantic_Web_Stack

 - The triple: underlying model of triples used to describe the relations between entities in the Semantic Web
   (subject) -- [predicate] --> (object)

 - RDF: Resource Description Framework
  1) a framework for representing information about resources on the WWW and beyond
  http://melancholy8914.blogspot.co.uk/2017/06/resource-description-framework.html

 - RDF Schema: RDF Vocabulary Description Language
  1) an RDF vocabulary which we can use to define other vocabularies
  http://melancholy8914.blogspot.co.uk/2017/06/rdf-schema.html

 - OWL: Web Ontology Language
  1) OWL provides more expressive features than RDF Schema
  http://melancholy8914.blogspot.co.uk/2017/06/ontologies.html

  http://melancholy8914.blogspot.co.uk/2017/06/web-ontology-language.html

 - SPARQL: the SPARQL Protocol and RDF Query Language
  http://melancholy8914.blogspot.co.uk/2017/06/sparql-protocol-and-rdf-query-language.html


5. Vocabularies and Applications
 - Social Networking
  1) FOAF
   * Friend Of A Friend
   * a machine readable ontology describing persons, their activities, and their relations to other people and objects
  http://www.ldodds.com/foaf/foaf-a-matic.html

  2) SIOC
   * Semantically-Interlinked Online Communities
   * ontology for describing interconnecting discussion methods like wikis, bulletin boards, blogs etc
  http://sioc-project.org/

 - Bibliographic Metadata
  1) Dublin Core
   * A standard set of 15 metadata elements for cross-domain information resource description
   * possibly the most widely used Semantic Web vocabulary
  http://dublincore.org

 - Cultural Heritage
  1) CIDOC CRM
   * ICOM's International committee for DOCumentation Conceptual Reference Model
   * ontology for heterogeneous cultural heritage information
  http://www.cidoc-crm.org/

 - Knowledge Organisation
  1) SKOS
   * Simple Knowledge Organisation System
   * standard vocabulary to support thesauri, classification schemes, subject heading lists, taxonomies, and other types of controlled vocabulary
   * semantic relationships: broader, narrower, related terms
  https://www.w3.org/2004/02/skos/

 - Web Annotation
  1) Annotea
   * shared annotations for the Web
   * Annotea-enabled browsers can query server to obtain annotations for pages
   * Open Annotation Data Model: a framework for creating associations between resources
 http://www.openannotation.org/spec/core/

 - Commerce
  1) Good Relations
   * standardised vocabulary for product, price, and company data