Introduction to Semantic Web

What is semantic? Semantics is the study of meaning. It is often used in ordinary language to denote a problem of understanding that comes down to word selection or connotation. In computer science, where it is considered as an application of mathematical logic, semantics reflects the meaning of programs or functions. For instance, the following statements use different syntaxes (languages), but result in the same semantic:

§ x += y (C, Java, etc.)

§ x := x + y (Pascal)

Semantics permits programs to be separated into their syntactical part (grammatical structure) and their semantic part (meaning). It encodes meanings separately from data and content files, and separately from application code.

Humans are capable of using the Web to carry out tasks such as finding the Finnish word for "monkey", reserving a library book, and searching for a low price for a DVD. However, a computer cannot accomplish the same tasks without human direction because web pages are designed to be read by people, not machines. The semantic web is a vision of information that is understandable by computers, so that they can perform more of the tedious work involved in finding, sharing, and combining information on the web.

The Semantic Web is an evolving extension of the World Wide Web in which the semantics of information and services on the web is defined, making it possible for the web to understand and satisfy the requests of people and machines to use the web content. It derives from World Wide Web Consortium director Sir Tim Berners-Lee's vision of the Web as a universal medium for data, information, and knowledge exchange. It provides a common framework that allows data to be shared and reused across application, website, enterprise, and community boundaries.

The Semantic Web is about two things. It is about common formats for integration and combination of data drawn from diverse sources, where on the original Web mainly concentrated on the interchange of documents. It is also about language for recording how the data relates to real world objects. That allows a person, or a machine, to start off in one database, and then move through an unending set of databases which are connected not by wires but by being about the same thing.

Semantic Models are both like and unlike other IT models:

• Like databases, ontologies are used by applications at run time (queried and reasoned over). Unlike databases, relationships are first-class constructs.
• Like object models, ontologies describe classes and attributes (properties). Unlike object models, ontologies are set-based and dynamic.
• Like business rules, they encode rules. Unlike business rules, ontologies organize rules using axioms.
• Like XML schemas, they are native to the web (and are in fact serialized in XML). Unlike XML schemas, Ontologies are graphs not trees, and used for reasoning.

Resources:

· http://en.wikipedia.org/wiki/Semantic_Web

· http://semanticweb.org/wiki/Main_Page

· http://www.w3.org/2001/sw/

· http://www.biomedcentral.com/1471-2105/8/S3/S2

· http://www.cs.washington.edu/research/semweb/email.html

· http://www.w3.org/2001/sw/SW-FAQ#swonbrowser

· http://en.wikipedia.org/wiki/Semantic_wiki