The document introduces the concepts of the Semantic Web and its goals. It discusses how the Semantic Web aims to add meaning to documents on the World Wide Web through standards like XML, RDF and ontologies. It provides an example of how the Semantic Web could understand information about a person like their schedule and help manage their daily life. The document outlines the chapters of the book, which will cover topics like XML, RDF, ontologies, knowledge representation and applications of Semantic Web technologies.

1. Chapter 1 The Semantic Web

2. Introduction
• World Wide Web: wide-area hypermedia
information retrieval initiative aiming to give
universal access to a large universe of
documents.
• The challenge of the Semantic Web, according
to Berners-Lee:
– To provide a language that expresses both data and
rules for reasoning about the data and that allows
rules from any existing knowledge representation
system to be exported onto the Web.
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3. Introduction
• Example 1.1: let us assume that Gopal is a professor.
– The Web wakes him up based on his lecture schedule as well as
depending on the day of the week.
– Web informs him about his schedule and appointments. He could also
get the details of how to reach a particular destination on that day.
– He could further informed of locations of his personal accessories.
– The Web manages all sorts of dynamic situations such as unexpected
events.
– On weekends, when he completes his work for the day, the Web makes
arrangements for him to meet his wife and kids for dinner in a restaurant
in the city.
• Web has completely taken over Gopal’s life and it makes
life easier but it is also up to Gopal to follow the advice
given by the Web.
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4. Evolution of the Web
Web in 1995 Web in 2000 Web in 2008
HTML, XML HTML, XML, RDF
HTML
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5. Hyper Text Transfer Protocol
• The request line from the client consists of
a request method, the address of the file
requested and the HTTP version number.
GET /mypage.html HTTP/1.1
– The above request calls for mypage.html file using the
GET HTTP method;
• A header looks like:
ACCEPT: */*
ACCEPT_LANGUAGE:en-us
REFERER:http://www.ntnu.org/dev03.html
USER_AGENT:FireFox/5.0 (compatible; MSIE 6.01;
Windows NT 6.0)
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6. Uniform Resource Identifier
• URL stands for Uniform Resource Locator, which means it is a uniform
(same throughout the world) way to locate a resource (file or document) on
the Internet.
• A Uniform Resource Identifier (URI) is an identifier used to identify objects
in a space.
URL is written as http://www.tmrfindia.org
Various URI schemes are,
• ftp://ftp.ac.bolt.org/class/class237.txt
• http://www.bolt.org/class/class123.txt
• ldap://[2003:db7::3]/c=GB?objectClass?one
• mailto:ram.seth@bsnl.in
• news:comp.infosystems.www.servers.unix
• tel:+91-230-247-7876
• telnet://164.0.1.12:80/
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7. A Layered Cake (W3C)
A layered cake consists of:
– Extensible Markup
Language (XML):
– XML Schema:
– Resource Description
Framework (RDF):
– RDF Schema:
– Ontology:
– Logic and Proof:
– Trust:
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8. Semantic Web Technologies
The Semantic Web
Information
XML, RDF, Metadata, Database Technology: Management
Agent Technology:
Ontologies, Data Transactions, Metadata, Technology:
DAML
Modelling Technologies Storage, Query Collaboration,
Knowledge Management
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9. Ontology
• Definition 1.1: An ontology is a formal, explicit
specification of a shared conceptualization.
– Ontologies describe data models in terms of classes,
subclasses, and properties.
– For instance, we can define a man to be a subclass of human,
which in turn is a subclass of animals that is a biped i.e. walks
on two legs.
– Ontologies are mainly categorized into two types:
– general ontologies (like SENSUS, Cyc, WordNet, etc.)
– domain-specific ontologies (like, GALEN – Generalized
Architecture for Languages, Encyclopedias, and
Nomenclatures in medicine; UMLS - Unified Medical Language
System).
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10. Semantics
• Definition 1.2: Semantic is a study of
meaning and changes of meaning.
• The different types of semantics are:
– Denotational Semantics:
– Operational Semantics:
– Axiomatic semantics:
– Model-Theoretic Semantics:
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11. Web Service
– Web Services is
• self-contained,
• self-describing,
• modular applications that can be published,
located, and invoked across the Web.
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12. Semantic Web Mining
• The Semantic Web
– to organize and browse the Web in ways more suitable to the
problems they have at hand.
– to impose a conceptual filter to a set of Web pages, and display
their relationships based on such a filter.
– to visualization of complex content. With HTML, such interfaces
are virtually impossible since it is difficult to extract meaning from
the text.
• The major concern of Semantic Web is to convert the
World Wide Web from just a huge repository of unrelated
text, into useful linked pieces of information.
– Linking the information is not only based on text similarity, but
mainly on the meanings and real-world relations between items.
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13. Book Overview
• Chapter 2: XML is a universal language for defining markup, it does not
provide with any means of talking about the semantics (i.e. meaning) of
data. XML helps Web document to become structured document. This
structure of a document can be made machine-accessible through DTDs
and XML schema.
• Chapter 3: RDF is a language for describing resources and RDF Schema is
a primitive ontology language. Both, RDF and RDF Schema, provide the
core languages for the Semantic Web.
• Chapter 4: This chapter deals with concept of ontology and ontology
languages. Here, we will also present some of the practical issues that arise
when building ontologies.
• Chapter 5: We will present some useful concepts from knowledge
representation and reasoning, especially description logic. This is a
backbone of some ontology languages.
• Chapter 6: This chapter presents some issues for building Semantic Web.
Actually, it is very difficult to predict the architecture of Semantic Web.
• Chapter 7: The chapter discusses a wide-ranging outline of the kinds of
techniques to which Semantic Web technology can be applied.
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14. Suggested Reading
– T. Berners-Lee, J. Hendler and O. Lassila. The
Semantic Web. Scientific American 284, 5, May
2001: 34-43.
– T. Berners-Lee. Weaving the Web. Harper 1999.
– T. Berners-Lee. Semantic Web Road Map.
http://www.w3.org/DesignIssues/Semantic
– T. Berners-Lee. Evolvability.
http://www.w3.org/DesignIssues/Evolution.html
– T. Berners-Lee. What the Semantic Web can
represent.
http://www.w3.org/DesignIssues/RDFnot.html
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