1. The Semantic Web
By: Maulik Parikh

2. The Semantic Web?
“The Semantic Web is an extension of the current web in which information is given well-defined meaning, better enabling computers and people to work in co- operation.“ [Berners-Lee et al, 2001]

3. Build of Semantic web
The emergence of the Semantic web is a natural progression in accredited information theories, borrowing concepts from the knowledge representation and knowledge management worlds as well as form revised thinking within World Wide web community.
The semantic web is much more expressive, comprehensive and powerful form of data modeling.

4. Does Semantic Web exist?
The Semantic Web currently exists as a vision, although a promising and captivating one. Similar to the current Web.
the Semantic web will be formed through a combination of open standard and proprietary protocols, frameworks, technologies, and services.

5. Semantic web, Semantic interoperability and Semantic Technologies
The terms “semantic interoperability” and “Semantic Technologies” are not interchangeable with the term “Semantic Web” much of the work on the Semantic Web is focused on the ambitious goal of allowing relatively universal and autonomous understanding of information on the internet.
Semantic interoperability represents a more limited or constrained subset of this goal.

7. Semantic web, Semantic interoperability and Semantic Technologies continued..
Semantic technologies is defined as a software technology that allows the meaning of and associations between information to be known and processed at a execution time.
For a semantic technology to be truly at work within a system there must be a knowledge model of some part of the world that is used by one or more applications at execution time

8. Today’s Web
Currently most of the Web content is suitable for human use.
Typical uses of the Web today are information seeking, publishing, and using, searching for people and products, shopping, reviewing catalogues, etc.
Dynamic pages generated based on information from databases but without original information structure found in databases.

9. Limitations of the Web Search today
The Web search results are high recall, low precision.
Results are highly sensitive to vocabulary.
Results are single Web pages.
Most of the publishing contents are not structured to allow logical reasoning and query answering.

10. Key components of the semantic Web
XML (extensible Markup Language)
RDF (Resource Description framework)
OWL ( Web Ontology Language)

11. XML (extensible Markup Language)
XML was developed in the late 1990s by the W3C as a standard way of describing, transporting, and exchanging data.
XML does not do anything by itself, but rather serves as a mechanism for describing data through the use of customized tags in a customized manner.
XML provides constructs such as document type definition (DTD) or XML Schema for defining these types of data exchange rules.

12. XML (extensible Markup Language)
Meaning of XML-Documents is intuitively clear
due to "semantic" Mark-Up
tags are domain-terms
But, computers do not have intuition
tag-names do not provide semantics for machines.
DTDs or XML Schema specify the structure of documents, not the meaning of the document contents
XML lacks a semantic model
has only a "surface model”, i.e. tree

13. XML: limitations for semantic markup
XML representation makes no commitment on:
Domain specific ontological vocabulary
Which words shall we use to describe a given set of concepts?
Ontological modelling primitives
How can we combine these concepts, e.g. “car is a-kind-of (subclass-of) vehicle”
RDF (Resource Description framework) is next step.

14. RDF (Resource Description framework)
RDF encodes information in sets of triples, each triple being rather like the subject, verb and object of an elementary sentence.
A Universal Resource Identifier (URI), similar to a URL for a Web page, identifies each of the triple elements.
The purpose of a URI is to uniquely identify a concept in the form of subject, verb or object by linking to the origin where the concept is defined. RDF provides an infrastructure for linking distributed metadata.

15. RDF: Basic Ideas Properties Properties are special kind of resources;
Properties describe relations between resources.
For example: “written by”, “composed by”, “title”, “topic”, etc.
Properties in RDF are also identified by URIs.
This provides a global, unique naming scheme.
Statements
A statement is an object-attribute-value triple.
It consists of a resources, a property, and a value.

16. RDF Schema: Basic Ideas
RDF is a universal language that enables users to describe their own vocabularies.
But, RDF does not make assumption about any particular domain.
It is up to user to define this in RDF schema.

17. Ontologies
The term ontology is originated from philosophy. In that context it is used as the name of a subfield of philosophy, namely, the study of the nature of existence.
For the Semantic Web purpose:
“An ontology is an explicit and formal specification of a conceptualization”. (R. Studer)
In general, an ontology describes formally a domain of discourse.
An ontology consists of a finite list of terms and the relationships between the terms.

18. Ontologies and Semantic Web
The terms denote important concepts classes of objects) of the domain.
For example, in a university setting, staff members, students, courses, modules, lecture theatres, and schools are some important concepts.
In the context of the Web, ontologies provide a shared understanding of a domain.
Such a shared understanding is necessary to overcome the difference in terminology.
Ontologies are useful for improving accuracy of Web searches.
Web searches can exploit generalization/specialization information

19. Ontology Spectrum Overview
Taxonomy
This is one of the simple form of semantic model, Taxonomies are defined simply as the structures used to organize information.
Thesaurus
This is more complex then a Taxonomy because its parent-child relationship.
Conceptual model & logical Theory
Conceptual Models and Logical Theories can be considered Ontology,Because the relationships are specified there is no longer a need for a strict structure that encompasses or defines the relationships.

20. Ontologies (OWL)
RDFS is useful, but does not solve all possible requirements
Complex applications may want more possibilities:
similarity and/or differences of terms (properties or classes)
construct classes, not just name them
can a program reason about some terms? E.g.:
“if «Person» resources «A» and «B» have the same «foaf: » property, then «A» and «B» are identical”
etc.
This lead to the development of OWL (Web Ontology Language)

21. OWL ( Web Ontology Language)
Whereas RDF's primary value can be seen in enabling integration of distributed data, OWL's main value is in enabling reasoning over distributed data. RDF and OWL can operate together or separately.
In RDFS, you can subclass existing classes… that’s all.
In OWL, you can construct classes from existing ones:
enumerate its content
through intersection, union, complement
through property restrictions

22. Semantic Web and AI? No human-level intelligence claims
As with today’s WWW
large, inconsistent, distributed
Requirements
scalable, robust, decentralised
tolerant, mediated
Semantic Web will make extensive use of current AI,
any advancement in AI will lead to a better Semantic Web
Current AI is already sufficient to go towards realizing the semantic web vision
As with WWW, Semantic Web will (need to) adapt fast

23. References
Barnaghi, Payam. "Introduction to the Semantic Web." Lecture.
W3C Semantic Web
The Semantic Web Community Portal,

24. Thank you!!