Information Search and Retrieval

8/7/2019 Information Search and Retrieval

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Information Search and Retrieval


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There are three different techniques in

search and Resource discovery paradigms,

Information searching & retrieval

Electronic directories & catalogs

Information filtering


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Information search & retrieval

Information search and retrieval is a process of

finding and extracting information according to the

specification provided by a user

The main purpose of developing this process is to

support nave users in areas like electronic shopping

and home banking.


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The goals of information search and

retrieval:

To satisfy the customers up to the maximum extent

To reduce the cost.

To fastly execute the requested query. Computer

methods that are used to execute the query are, Method for finding exact match based on keyword.

Method for finding nearest neighbors.

Information search and retrieval is used in areas like

libraries where customers are concentrating oninformation seeking behavior.


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Electronic Directories and Catalogs

Directories and catalogs are used for the

following tasks

1)Information organizing 2)Information browsing


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Information Organizing:

Organizing refers to the way of organizing orarranging the information so as to make decisionsfor interrelating it.

Organizing the information in a static way isuseful for some people but causes harm to otherpeople.

The apprehension of organizing the information is

very intuitive which means that what one findseasy may be difficult for others to browsedepending on the requirement.


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Information Browsing:

It is defines as an activity that is guided by human foranalyzing the enterprise and identifying the details of

resource space.

There are two major problems that occur while

performing browsing, they are navigation issues anddisorientation issues of users.

These problems can be solved by using system that

supports different representation of similar

information.


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Information Filtering:

The objective f information filtering is to provide

access to relevant and variable information when a

user requests for it.

Information filtering is a process of selecting only

those information that matches the users request.

The purpose of this process is not responsible for

performing any kind of search but its only objective isto filter out inconsistent data.


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Software filters are used to provide access control.

local filter

Remote filter

Local filter:

Local filters are used for processing incoming streamof data.

Remote filters:

They are software agents that perform their task on

behalf of users. They help users to perform daily task,search and retrieve information, support decision-making


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INFORMATION SEARCH AND

RE

TRIEV

AL

Searching is a process of identifying/finding the

required information from a massive amount of

stored semi structured information. This is in contrast

to the database application that deals with thestructured format since it follow certain standards,

syntaxes and make use of data type that have

specific meaning

Examples: students database and email messages.


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There are two phases in which search process can be

accomplished. They are

End user retrieval phase

Publisher indexing phase.


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End user Retrieval phase:

The following steps must be followed in end user retrievalphase are,

A query is constructed by a user which specifies the search

method to be used.

Query is then sent to the server , that examines the query,process it and initiate the search process. The result is a

table that contains a list of matching documents called hit

list. This tables finally degenerate hit list is passed back to

the user.

Users then select the pertinent document according to

their requirement , scans it and print only the desired part

of a document.


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Publisher Indexing phase:

This phase is responsible for,

Making an entry of a document in the database.

Creating and updating indexes and pointers that are useful

while searching is performed


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What is a Document?

Examples: web pages, email, books, news stories,

scholarly papers, text messages, Word, Power point, PDF,forum postings, patents, IM sessions, etc.

Common properties

Significant text contentSome structure (e.g., title, author, date for papers;

subject, sender, destination for email)


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Documents vs. Database Records

Database records (or tuples in relational databases)

are typically made up of well-defined fields (or

attributes)e.g., bank records with account numbers,

balances, names, addresses, social security numbers,

dates of birth, etc.

Easy to compare fields with well-defined semantics to

queries in order to find matches

Text is more difficult


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Dimensions of IRContent Applications Tasks

Text Web search Ad hoc search

Images Vertical search Filtering

Video Enterprise search ClassificationScanned docs Desktop search Question answering

Audio Forum search

Music P2P search

Literature search


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InfrmationRetrievalTasks

Ad-hoc search Find relevant documents for an

arbitrary text query

Filtering Identify relevant user profiles for a newdocument

Classification Identify relevant labels for documents

Question answering Give a specific answer to a

question


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Models of Information Retrieval:

There are three models that are used for retrieving

information from the database in an efficient

manner. They are

Boolean information retrieval model

Vector space information retrieval model

Probabilistic information retrieval model


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Boolean information retrieval model:

Boolean refers to query specification which are foundusing word or phrases, which are combined usingstandard operators AND, OR, NOT.

The drawback of this model fetches those text filesirrespective of their locations.

The drawback of this model is that it does not giveany preference or priority to fetched document

The system is more effective if a query exactlymatches with the retrieved document and on theother hand results ineffectiveness id the result is notdefinite and accurate.


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Vector space information retrieval model

Vector space model is developed to overcome the

problems of Boolean model.

It performs vector comparison using cosine

correlation similarity method.

According to this method, the query matches the

text, when vector text is similar to vector query.


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Probabilistic information retrieval model:

This model is based on probability ranking criterion.

According to this criteria, every text present in the

database is given some priority.

Both vector space model and probabilistic model uses

Boolean queries.


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CHALLENGES AND PROBLEMS

ENCOUNTERD IN INFORMATION SEARCH The following are the various challenges that a rises

while searching information online.

Information is being uploaded on the internet at ahigh rate.

Since, the turnover of information is rapid, traditionaltools of information search are not sufficient for theconsumers. Therefore, a challenge is to design and

implement advances searching, filtering and datamining tools that maximize the search process of anindividual in terms of time, cost and informationneeds


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Sometimes the search results gets overloaded often

confusing the consumers.

Consumer learn the environment slowly by knowing what iswhere. Additionally, directories and catalogs may be provided

to the consumers that facilitate them to navigate and browse

the product information of their choice.

Today, the focus is on human technology interfaces,according to this feature, the information regarding

preferences of a customer is taken and intelligent and useful

information is provided to the consumer, but the challenge

here is, how to represent this useful information on thescreen. Developments are being made to use virtual reality for

displaying such information to user