IST 2140 Information Storage and Retrieval

1
IST 2140Information Storage and Retrieval

• Week 1

2
What is information?

• something that (1) is represented by a set of
  symbols, (2) has some structure, and (3) can be
  read and to some extent understood by users of
  information (Meadow)
• Data to information to knowledge continuum

3
What is Information Retrieval?

• the location and presentation to a user of
  information relevant to an information need
  expressed as a query (Korfhage)
• "an information retrieval system is a device
  interposed between a potential user of
  information and the information collection
  itself. For a given information problem, the
  purpose of the system is to capture wanted items
  and to filter out unwanted items (Harter)
•  "information retrieval deals with the
  representation, storage, and access to documents
  or representatives of documents (document
  surrogates) (Salton)
• Document may be text or ??

4
What is an Information Need? 

• Information problem that causes the user to act
• Four levels
• Visceral recognition of deficiency, though not
  cognitively defined (gap or anomalous state of
  knowledge defect in mental model)
• Conscious users characterization of the
  deficiency
• Formalized users clear articulation
• Compromised  formalized statement as limited by
  the search system

5
The IR process

• first approach to computer IR IR is a simple
  matching process QUERY----gt FILE ----gt
  ANSWER
• now realize it is an extremely complex process
  because
• Information need is amorphous/hard to express
• Document representation is inexact/ambiguous
• Probabilistic rather than deterministic process
• cf. retrieval from a DBMS

6
Sample search

• Search bridge on Google
• http//www.google.com
• And on Northern Light
• http//www.northernlight.com
• The problem of homonyms is just one of many in IR

7
Major functions of information services
8
What are the components of an IR system?

• Document processing (indexing)
• Query input
• Document-query matching
• Output module
• Feedback module
• User interface

9
Processing In a Boolean IR System
10
Some questions for IR

• how does an individual approach an IR system?
• how can the content ("value") of an item be
  represented?
• how can the individual and the information be
  brought together ("matched")?
• what is an appropriate way to present the
  results?
• how can the success or failure of information
  seeking activity be measured?
• how should the ISAR system be structured for
  maximum effectiveness? maximum efficiency?

11
Who builds information retrieval systems?

• Commercial information providers
• DIALOG, LEXIS-NEXIS, WestLaw, STN
• Text Software vendors
• InMagic, AskSam
• IR Researchers
• SMART, InQuery, Okapi, ZPRISE, Panoptics, Lemur
• Web search engine designers
• AltaVista, Google, Lycos, etc.  

12
Information retrieval system design and analysis

• The system-centered approach
• Salton, Croft, Van Rijsbergen, Lewis
• The user-centered approach
• Belkin, Marchionini, Fidel, Ingwersen

13
Sources of Information on IR

• journals
• Information Retrieval (IR)
• Information Processing Management (IPM)
• Journal of the American Society for Information
  Science and Technology (JASIST)
• Transactions on Information Systems (TOIS)
• conferences
• ACM SIGIR (Special Interest Group on Information
  Retrieval)
• American Society for Information Science and
  Technology
• TREC (Text REtrieval Evaluation Conference)

14
(No Transcript)