1, definition of FOA
The process of Finding Out About
(FOA) is a series of cognitive activities, which helps decision-makers focus on
knowledge relevant to the topic of search and operate on the large collections
of linguistic objects by FOA searching techniques. The semantic meanings of linguistic objects
are essential for FOA. We usually draw
on others' opinion by communicating with others, reading valuable writings in
library, searching the Internet and so
on. Well-arranged linguistic expressions enable people to understand knowledge
wholly and represent own opinion more clear.
2, the process of FOA
The FOA conversion loop includes
three phases:
(1) Asking a question;
Users turn their information need into external expression of questions,
proposing query.
(2) Constructing an answer;Search engine is a computer program that algorithmically performs the task to answer users' questions or query.
(3) Assessing the answer.
This is a closing of the FOA
conversion loop. Making use of asker's relevance feedback fully provides more
information with their reaction to each retrieved document.
3, Information Retrieval
IR is concerned with
representing, searching, and manipulating large collections of electronic text
and other human-language data.
4, IR Applications:
(1) Web Search Engine
Web search engines are….., based
on clusters of computers which work cooperatively to generate a ranked list of
Web pages without redundant and duplicate pages to satisfy users' information
need embodied in the query. The rank of
the Web pages usually abide by the search engine 's ranking algorithm, which
keeps several features including the content and structure of pages, the
relation to other pages, the content and structure of the Web as a whole, and
characteristics of user such as geographic location or past searching behavior in
balance.
(2)Desktop and File System Search
Engines
(3)Document Management and Search
Service(4)Digital Libraries and Other Specialized IR Systems
(5)Other IR Applications
Associated with Storage, Manipulation, and Retrieval of Human-Language Data
For example, news aggregator,
e-mail system, text clustering and categorization systems, summarization
systems, information extraction systems, Topic detection and tracking systems,
expert search systems, question answering systems, and multimedia information
retrieval systems.
5, Basic Information Retrieval
Systems Architecture
User constructs a topic depending
on the information need, and issues a query which consists of terms to the IR
system. Then a search engine accepts user's queries and processes them by
maintaining and manipulating an inverted index for a document collection, which
forms the principal data structure used by the search engine. The search engine sorts relevant documents according
to the score or the retrieval status value (RSV) for each document. After
eliminating the redundant and duplicate results, the search engine reports the
ranked result list for further processing.
6, IR System Performance
Evaluation
There are two aspects: efficiency
and effectiveness.
Efficiency may be measured in
terms of time and space.
Effectiveness may be measured in terms
of relevance, depending on human judgment.
7,IR Problem
There are two crucial problems:(1) How to exactly extract information from documents;
(2) How to decide the relevance which depends on use's assessment for solving query.
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