INFORMATION RETRIEVAL

'Information retrieval (IR)' is the science of searching for information in documents, searching for documents themselves, searching for metadata which describe documents, or searching within databases, whether relational stand-alone databases or hypertextually-networked databases such as the World Wide Web. There is a common confusion, however, between data retrieval, document retrieval, information retrieval, and text retrieval, and each of these has its own bodies of literature, theory, praxis and technologies. IR is interdisciplinary, based on computer science, mathematics, library science, information science, cognitive psychology, linguistics, statistics and physics.
Automated IR systems are used to reduce information overload. Many universities and public libraries use IR systems to provide access to books, journals, and other documents. IR systems are often related to object and query. Queries are formal statements of information needs that are put to an IR system by the user. An object is an entity which keeps or stores information in a database. User queries are matched to objects stored in the database. A document is, therefore, a data object. Often the documents themselves are not kept or stored directly in the IR system, but are instead represented in the system by document surrogates.
In 1992 the US Department of Defense, along with the National Institute of Standards and Technology (NIST), cosponsored the Text Retrieval Conference (TREC) as part of the TIPSTER text program. The aim of this was to look into the information retrieval community by supplying the infrastructure that was needed for such a huge evaluation of text retrieval methodologies.
Web search engines such as Google, Yahoo search or Live.com are the most visible IR applications.

Contents
Performance measures
Precision
Recall
Fall-Out
F-measure
Average precision
Model types
First dimension: mathematical basis
Second dimension: properties of the model
Timeline
Open source systems
Other retrieval tools
Research Groups (in no particular order)
Major figures
Other figures associated with information retrieval
ACM SIGIR Gerard Salton Award
See also
External links

Performance measures


There are several measures on the performance of an information retrieval system. The measures rely on a collection of documents and a query for which the relevancy of the documents is known. All common measures described here assume a ground truth notion of relevancy: every document is known to be either relevant or non-relevant to a particular query. In practice queries may be ill-posed and there may be different shades of relevancy.
Precision

The proportion of retrieved ''and'' relevant documents to all the documents retrieved:
: mbox{precision}= rac{|{mbox{relevant documents}}cap{mbox{retrieved documents}}|}{|{mbox{retrieved documents}}|}
In binary classification, precision is analogous to positive predictive value. Precision takes all retrieved documents into account. It can also be evaluated at a given cut-off rank, considering only the topmost results returned by the system. This measure is ''called precision at n'' or ''P@n''.
Note that the meaning and usage of "precision" in the field of Information Retrieval differs from the definition of accuracy and precision within other branches of science and technology.
Recall

The proportion of relevant documents that are retrieved, out of all relevant documents available:
:mbox{recall}= rac{|{mbox{relevant documents}}cap{mbox{retrieved documents}}|}{|{mbox{relevant documents}}|}
In binary classification, recall is called sensitivity.
It is trivial to achieve recall of 100% by returning all documents in response to any query. Therefore recall alone is not enough but one needs to measure the number of non-relevant document also, for example by computing the precision.
Fall-Out

The proportion of non-relevant documents that are retrieved, out of all non-relevant documents available:
: mbox{fall-out}= rac{|{mbox{non-relevant documents}}cap{mbox{retrieved documents}}|}{|{mbox{non-relevant documents}}|}
F-measure

The weighted harmonic mean of precision and recall, the traditional F-measure or balanced F-score is:
:F = 2 cdot (mathrm{precision} cdot mathrm{recall}) / (mathrm{precision} + mathrm{recall}).,
This is also known as the F_1 measure, because recall and precision are evenly weighted.
The general formula for non-negative real α is:
:F_lpha = (1 + lpha) cdot (mathrm{precision} cdot mathrm{recall}) / (lpha cdot mathrm{precision} + mathrm{recall}).,
Two other commonly used F measures are the F_{2} measure, which weights recall twice as much as precision, and the F_{0.5} measure, which weights precision twice as much as recall.
Average precision

The precision and recall are based on the whole list of documents returned by the system. Average precision emphasizes returning more relevant documents earlier. It is average of precisions computed after truncating the list after each of the relevant documents in turn:
: operatorname{Ave}P = rac{sum_{r=1}^N (P(r) imes mathrm{rel}(r))}{mbox{number of relevant documents}} !,
where ''r'' is the rank, ''N'' the number retrieved, ''rel()'' a binary function on the relevance of a given rank, and ''P()'' precision at a given cut-off rank.
If there are several queries with known relevancies available, the ''mean average precision'' is the mean value of the average precisions computed for each of the queries separately.

Model types


categorization of IR-models (translated from German entry, original source Dominik Kuropka)

For successful IR, it is necessary to represent the documents in some way. There are a number of models for this purpose. They can be categorized according to two dimensions like those shown in the figure on the right: the mathematical basis and the properties of the model. (translated from German entry, original source Dominik Kuropka)
First dimension: mathematical basis


★ ''Set-theoretic Models'' represent documents by sets. Similarities are usually derived from set-theoretic operations on those sets. Common models are:


Standard Boolean model


Extended Boolean model


fuzzy retrieval

★ ''Algebraic Models'' represent documents and queries usually as vectors, matrices or tuples. Those vectors, matrices or tuples are transformed by the use of a finite number of algebraic operations to a one-dimensional similarity measurement.


Vector space model


Generalized vector space model


★ Topic-based vector space model (literature: [1], [2])


Extended Boolean model


★ Enhanced topic-based vector space model (literature: [3], [4])


★ Latent semantic indexing aka latent semantic analysis

★ ''Probabilistic Models'' treat the process of document retrieval as a multistage random experiment. Similarities are thus represented as probabilities. Probabilistic theorems like the Bayes' theorem are often used in these models.


Binary independence retrieval


Probabilistic relevance model (BM25)


★ Uncertain inference


Language models


Divergence from randomness models


Latent Dirichlet Allocation
Second dimension: properties of the model


★ ''Models without term-interdependencies'' treat different terms/words as not interdependent. This fact is usually represented in vector space models by the orthogonality assumption of term vectors or in probabilistic models by an independency assumption for term variables.

★ ''Models with immanent term interdependencies'' allow a representation of interdependencies between terms. However the degree of the interdependency between two terms is defined by the model itself. It is usually directly or indirectly derived (e.g. by dimensional reduction) from the co-occurrence of those terms in the whole set of documents.

★ ''Models with transcendent term interdependencies'' allow a representation of interdependencies between terms, but they do not allege how the interdependency between two terms is defined. They relay an external source for the degree of interdependency between two terms. (For example a human or sophisticated algorithms.)

Timeline



★ 1890: Hollerith tabulating machines were used to analyze the US census. (Herman Hollerith).

★ 1945: Vannevar Bush's ''As We May Think'' appeared in ''Atlantic Monthly''

★ Late 1940s: The US military confronted problems of indexing and retrieval of wartime scientific research documents captured from Germans.

★ 1947: Hans Peter Luhn (research engineer at IBM since 1941) began work on a mechanized, punch card based system for searching chemical compounds.

★ 1950: The term "information retrieval" may have been coined by Calvin Mooers.

★ 1950s: Growing concern in the US for a "science gap" with the SSSR motivated, encouraged funding, and provided a backdrop for mechanized literature searching systems (Allen Kent et al) and the invention of citation indexing (Eugene Garfield).

★ 1955: Allen Kent joined Case Western Reserve University, and eventually becomes associate director of the Center for Documentation and Communications Research.

★ 1958: International Conference on Scientific Information Washington DC included consideration of IR systems as a solution to problems identified. See: Proceedings of the International Conference on Scientific Information, 1958 (National Academy of Sciences, Washington, DC, 1959)

★ 1959: Hans Peter Luhn published "Auto-encoding of documents for information retrieval."

★ 1960: Melvin Earl (Bill) Maron and J. L. Kuhns published "On relevance, probabilistic indexing, and information retrieval" in Journal of the ACM 7(3):216-244, July 1960.

★ Early 1960s: Gerard Salton began work on IR at Harvard, later moved to Cornell.

★ 1962: Cyril W. Cleverdon published early findings of the Cranfield studies, developing a model for IR system evaluation. See: Cyril W. Cleverdon, "Report on the Testing and Analysis of an Investigation into the Comparative Efficiency of Indexing Systems". Cranfield Coll. of Aeronautics, Cranfield, England, 1962.

★ 1962: Kent published Information Analysis and Retrieval

★ 1963: Weinberg report "Science, Government and Information" gave a full articulation of the idea of a "crisis of scientific information." The report was named after Dr. Alvin Weinberg.

★ 1963: Joseph Becker and Robert Hayes published text on information retrieval. Becker, Joseph; Hayes, Robert Mayo. Information storage and retrieval: tools, elements, theories. New York, Wiley (1963).

★ 1964: Karen Spärck Jones finished her thesis at Cambridge, ''Synonymy and Semantic Classification'', and continued work on computational linguistics as it applies to IR

★ 1964: The National Bureau of Standards sponsored a symposium titled "Statistical Association Methods for Mechanized Documentation." Several highly significant papers, including G. Salton's first published reference (we believe) to the SMART system.

★ Mid-1960s: National Library of Medicine developed MEDLARS Medical Literature Analysis and Retrieval System, the first major machine-readable database and batch retrieval system

★ Mid-1960s: Project Intrex at MIT

★ 1965: J. C. R. Licklider published ''Libraries of the Future''

★ 1966: Don Swanson was involved in studies at University of Chicago on Requirements for Future Catalogs

★ 1968: Gerard Salton published ''Automatic Information Organization and Retrieval''.

★ 1968: J. W. Sammon's RADC Tech report "Some Mathematics of Information Storage and Retrieval..." outlined the vector model.

★ 1969: Sammon's "A nonlinear mapping for data structure analysis" (IEEE Transactions on Computers) was the first proposal for visualization interface to an IR system.

★ Late 1960s: F. W. Lancaster completed evaluation studies of the MEDLARS system and published the first edition of his text on information retrieval

★ Early 1970s: first online systems--NLM's AIM-TWX, MEDLINE; Lockheed's Dialog; SDC's ORBIT

★ Early 1970s: Theodor Nelson promoting concept of hypertext, published Computer Lib/Dream Machines

★ 1971: N. Jardine and C. J. Van Rijsbergen published "The use of hierarchic clustering in information retrieval", which articulated the "cluster hypothesis." (Information Storage and Retrieval, 7(5), pp. 217-240, Dec 1971)

★ 1975: Three highly influential publications by Salton fully articulated his vector processing framework and term discrimination model:


★ A Theory of Indexing (Society for Industrial and Applied Mathematics)


★ "A theory of term importance in automatic text analysis", (JASIS v. 26)


★ "A vector space model for automatic indexing", (CACM 18:11)

★ 1978: The First ACM SIGIR conference.

★ 1979: C. J. Van Rijsbergen published ''Information Retrieval'' (Butterworths). Heavy emphasis on probabilistic models.

★ 1980: First international ACM SIGIR conference, joint with British Computer Society IR group in Cambridge

★ 1982: Belkin, Oddy, and Brooks proposed the ASK (Anomalous State of Knowledge) viewpoint for information retrieval. This was an important concept, though their automated analysis tool proved ultimately disappointing.

★ 1983: Salton (and M. McGill) published Introduction to Modern Information Retrieval (McGraw-Hill), with heavy emphasis on vector models.

★ Mid-1980s: Efforts to develop end user versions of commercial IR systems.

★ 1985-1993: Key papers on and experimental systems for visualization interfaces.

★ Work by D. B. Crouch, Robert R. Korfhage, M. Chalmers, A. Spoerri and others.

★ 1989: First World Wide Web proposals by Tim Berners-Lee at CERN.

★ 1992: First TREC conference.

★ 1997: Publication of Korfhage's ''Information Retrieval'' with emphasis on visualization and multi-reference point systems.

★ Late 1990s: Web search engine implementation of many features formerly found only in experimental IR systems

Open source systems



DataparkSearch, search engine written in C, GPL

Egothor high-performance, full-featured text search engine written entirely in Java

Glimpse and Webglimpse advanced site search software

ht://dig Open source web crawling software

Lemur Language Modelling IR Toolkit

Lucene [5] Apache Jakarta project

MG full-text retrieval system Now maintained by the Greenstone Digital Library Software Project

★ [ftp://ftp.cs.cornell.edu/pub/smart/ Smart] Early IR engine from Cornell University

Sphinx [6] Open-source (GPL) SQL full-text search engine

Terrier TERabyte RetrIEveR, Information Retrieval Platform, written in Java

Wumpus multi-user information retrieval system

Xapian Open source IR platform based on Muscat

Zebra GPL structured text/XML/MARC boolean search IR engine supporting Z39.50 and Web Services

Zettair, compact and fast search engine written in C, able to handle large amounts of text

Other retrieval tools



ASPseek

iHOP Information retrieval system for the biomedical domain

MEDIE An intelligent search engine, retrieving biomedical events from Medline.

EBIMed Information retrieval (and extraction) system over Medline

Info-PubMed Protein interaction database with 200,000 gene/protein names mined from Medline.

Fluid Dynamics Search Engine (FDSE) A search engine written in Perl, freeware and shareware versions are available

GalaTex XQuery Full-Text Search (XML query text search)

Information Storage and Retrieval Using Mumps (Online GPL Text)

mnoGoSearch written in C, it can index web multilingual sites and many databases types.

Sphinx Free SQL full-text search engine

BioSpider Free metabolite/drug/protein information retrieval system (used in the annotation of DrugBank and the Human Metabolome Database)

Research Groups (in no particular order)



Center for Intelligent Information Retrieval at UMASS

Information Retrieval at the Language Technologies Institute, Carnegie Mellon University

Information Retrieval at Microsoft Research Cambridge

Glasgow Information Retrieval Group

CIR Centre for Information Retrieval

Centre for Interactive Systems Research at City University, London

IIT Information Retrieval Lab

Information Retrieval Group at Université de Neuchâtel

PSU Intelligent Systems Research Laboratory

Information and Language Processing Systems at the University of Amsterdam

Information Retrieval Laboratory, Harbin Institute of Technology (mainly in Chinese)

Information Retrieval Group at the University of Waterloo, Canada

Information Retrieval Group at the Queen Mary University of London

Information Retrieval Lab at the University of A Coruña

Major figures



Gerard Salton

Hans Peter Luhn

W. Bruce Croft

Karen Spärck Jones

C. J. van Rijsbergen

Donald Kraft

Stephen E. Robertson

Abraham Bookstein

Stephen P Harter

David Blair

Other figures associated with information retrieval



Vannevar Bush

Paul DeMaine

Douglas Engelbart

Eugene Garfield

Robert R. Korfhage

Calvin Mooers

Ted Nelson

Don Swanson
Awards in this field: Tony Kent Strix award.

ACM SIGIR Gerard Salton Award


; 1983 - Gerard Salton, Cornell University : "About the future of automatic information retrieval"
; 1988 - Karen Spärck Jones, University of Cambridge : "A look back and a look forward"
; 1991 - Cyril Cleverdon, Cranfield Institute of Technology : "The significance of the Cranfield tests on index languages"
; 1994 - William S. Cooper, University of California, Berkeley : "The formalism of probability theory in IR: a foundation or an encumbrance?"
; 1997 - Tefko Saracevic, Rutgers University : "Users lost: reflections on the past, future, and limits of information science"
; 2000 - Stephen E. Robertson, City University, London : "On theoretical argument in information retrieval"
; 2003 - W. Bruce Croft, University of Massachusetts, Amherst : "Information retrieval and computer science: an evolving relationship"
; 2006 - C. J. van Rijsbergen, University of Glasgow, UK : "Quantum haystacks"

See also



Adversarial information retrieval

Controlled vocabulary

Cross Language Evaluation Forum

Cross-language information retrieval

Digital libraries

Document classification

Educational psychology

Free text search

Geographic information system

Information extraction

Information science

Knowledge visualization

Question answering

Relevance feedback

Search engines

Search index

Spoken document retrieval

tf-idf

SP theory

External links



ACM SIGIR: Information Retrieval Special Interest Group

BCS IRSG: British Computer Society - Information Retrieval Specialist Group

Text Retrieval Conference (TREC)

Chinese Web Information Retrieval Forum (CWIRF)

Information Retrieval (online book) by C. J. van Rijsbergen

Information Retrieval Wiki

Information Retrieval resources (Google search)

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