semantic webce.sharif.edu/courses/90-91/2/ce694-1/resources...the introduction of the world wide...

بسمه تعالی

Semantic Web

Morteza Amini

Introduction to Semantic Web

Sharif University of Technology Spring 90-91

Outline

Thinking and Intelligent Applications

The World Wide Web History

The Problem with the Web

Machine-Processable Data

Semantic Technology & Semantic Layer Cake

Sharif Univ. of Tech. Introduction to Semantic Web - Morteza Amini 2

Outline








Thinking is the most important aspect of human existence:

Aristotle describes Human as Rational Animals

But what is thinking?

In general, thinking can be a complex process that uses concepts, their interrelationships, and inference or deduction, to produce new knowledge.

However, thinking is often used to describe such disparate acts as

memory recall,

Arithmetic calculations,

creating stories,

decision making, and so on.

Sharif Univ. of Tech. 4 Introduction to Semantic Web - Morteza Amini


The term intelligence can be applied to nonhuman

entities as we do in the field of Artificial Intelligence (AI).

But frequently we mean something somewhat different

than in the case of human intelligence.

For example,

a child who can perform difficult arithmetic calculations quickly

a computer that could perform the same calculations faster



Human thinking involves complicated interactions within the

biological components of the brain, and that the process of

learning is also an important element of human intelligence.

Increasingly, software applications perform tasks that are

sufficiently complex and human-like that the term intelligent

may be appropriate.

AI can be seen as the science of machines that behave

intelligently (or simulate intelligent behavior)

The concept of intelligent applications entails the efforts to

take advantage of AI technologies to enhance applications and

make them act in more intelligent ways.


Outline



The Problem with the Webs





The history of the Web extends back more than 40 years.

Early signs of network architecture in the 1960s by

ARPANET project. A network between universities and

research laboratories.

The ARPANET was a success right from the very

beginning.

Few years later, the network developed

New sites (nodes)

New capabilities and features (such as software)

New protocols to facilitate email and file transfers



The mid-1980s marked a boom in the personal computer and superminicomputer industries.

Internet used to communicate with each other and with their customers.

By 1990,

the ARPANET was decommissioned,

leaving only the vast network-of-networks called the Internet with over 300,000 hosts.

Three events fueled the internet:

the introduction of the World Wide Web,

the widespread availability of the graphical browsers,

the unleashing of commercialization.


The World Wide Web

HTTP (how to transfer data)

GET /index.html

URI (how to address data)

http://www.sharif.ir/

HTML (how to mark up data for human reader)

<html><head><title>.....


Outline








Billions of pages with static data representations that are

designed for direct human.

Problems in:

Search and retrieving documents

Extracting relevant data from retrieved documents

Combining information from different sources to achieve a

particular goal


Search and Retrieving Documents

How can we find some documents on a subject in this

huge volume of non-specified information?


Extracting Information (1)

Which

book is

about

security?


Extracting Information (2)

What is the

price of the

book?


Combining Information

Where can I find the cheapest copy of “Computer

Security”?


Outline







The Solution

Instead of publishing static represented data in natural

language, publish machine-processable data!

Publish information in terms understandable for a

machine

Ask questions in terms understandable for a machine

And: make sure all machines understand your terms!

This is what envisioned as Semantic Web.


Machine-Processable Data (1)

Publishing:

B related-to A

C related-to A

D related-to C

Querying (give me all things related to A):

?x related-to A

Answer:

?x = B

?x = C


Machine-Processable Data (2)

Publishing (related-to is transitive):

B related-to A

C related-to A

D related-to C

?x related-to ?y and ?y related-to ?z ?x related-to ?z

Querying (give me all things related to A):

?x related-to A

Answer:

?x = B

?x = C

?x = D


Outline







Semantic Technology

Semantic Technology (by Davis's definition) semantic technology is "a collection of software standards and

methodologies that are aimed at providing more explicit meaning for the information in a computational environment".

Semantics in semantic technology is interpreted as the mapping between the structured data or concepts and the set of objects. In this way, it provides a common understanding and interpretation

about the concepts for machines and humans.

Semantic technology encodes meanings (semantics) in an abstract layer by describing the structure of the knowledge we have about them. separately from data and content files, and separately from

application code.


Semantic Layer Cake (1)

The semantic layer cake provides a framework to present a variety of approaches to provide the meta-data that describe the abstract layer (semantics or meaning of underlying resources and information).

More upper layer provides more vocabulary and thus more meaning (semantics).


Semantic Layer Cake (2)

We talk more about the different layers of the semantic

layer cake, during this course.

A semantic data model, which is more often leveraged to

represent and share knowledge in a distributed world

using semantic technology, is ontology.

So, our main focus will be on ontologies.

Ontology languages (based on Description Logics)

Ontology engineering

Ontology matching


Any Question...

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