LIS618 lecture 1

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LIS618 lecture 1

• Thomas Krichel
• 2004-02-01

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structure of talk

• Recap on Boolean (aurally)
• Before online searching
• Working with DIALOG
• Overview
• Search command
• Boolean exercise (on the fly)

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before a search I

• What is the purpose of the query?
• brief overview
• comprehensive search
• What perspective on the topic is required?
• scholarly
• technical
• business
• popular

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before search II

• What type of information does the patron want?
• fulltext
• bibliographic
• directory
• numeric
• Are there any known sources?
• authors
• journals
• papers
• conferences

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before search III

• What are the language restrictions?
• What, if any, are the cost restrictions?
• How current need the data to be?
• How much of each record is required?

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concept analysis

• This is the art/science of taking the topic to
  search for and develop facets. Example Internet
  filtering in Libraries
• Internet filter
• Libraries
• Controversy not technical issues
• We may also need the think about the aim of the
  search.

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search aims

• a known needle in a known haystack
• a known needle in an unknown haystack
• an unknown needle in an unknown haystack
• any needle in a haystack
• the sharpest needle in a haystack
• most of the sharpest needles in a haystack

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search aims

• all the needles in a haystack
• affirmation of no needles in a haystack
• things like needles in a haystack
• is there a new needle in the haystack
• where are the haystacks
• needles, haystacks, anything

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types of searches

• known-item searches
• negative searches
• selective dissemination of information
• topical or subject searches
• passage searching, where the user is only
  interested in part of the item

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search strategies I

• Building block approach
• Do a number of elementary searches
• Combine the resulting sets with Boolean operators
• This is what I did in the example in the previous
  lecture
• Works only with the Boolean model

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search strategies II

• Snowballing approach
• Start with a very specific query
• Think of other term that can be added to get more
  results
• Stop when a reasonable number of results are
  achieved.
• Not sure this really works well in practice.

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search strategies III

• The successive fraction approach is the opposite
  of the snowballing approach
• First search for a broad concept
• Then repeat the query by adding various limiting
  factors.
• Can work well if the IR system allows to repeat
  and edit queries.
• But queries can become unwieldy.

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search strategies IV

• Most specific facet first
• Conduct concept analysis
• Look for the most specific facet
• Search that first, add others later
• Presupposes that you have done a decent concept
  analysis.

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two steps in DIALOG

• step one select databases (aka files) to look at
  
• step two perform searches on the selected
  databases
• You may wonder why one does not have one single
  step like in a search engine. Discuss.
• today we concentrate on the second step

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working on selected files

• We assume that we have selected database that we
  know and we look at the search interface on the
  selected database.
• The database selection process is a bit more
  complicated, covered next week.
• First, let us login and look at the command
  prompt.
• Then we select the first database (file) with the
  begin command

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the begin command

• As its name suggests, usually the first command.
• begin number, number,
• selects files with numbers number
• Once they are selected they can be searched.
• Now select the ERIC "begin 1"
• "Begin 1" can be abbreviated as "b 1"

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substeps in the second step

• Identify search terms
• Use Dialog basic commands to conduct a search
• View records online or print the results

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the 's' (select) command

• Once issued the "begin" command to select a
  database, we issue the "s" command on the
  database.
• "s query_expression" where query_expression is a
  query expression.
• This will search the index of selected database
  in full-text view for the query issued
• It will not find any of the following "an and by
  for from of the to with". They are stop words.

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query expression

• A query expression contains search terms
  expressed in special ways
• You can truncate search terms.
• You can build an elementary expression by putting
  several keywords together. This is achieved by
  DIALOG's connectors.
• You can combine several expressions with the use
  of Boolean operators
• We will cover this is in turn now.

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truncation of terms I

• Open Truncation
• "select path?" retrieves all words that begin
  with path paths, pathos, pathway, pathology
• Controlled-Length Truncation
• "select path??" retrieves the root and up to two
  additional characters paths, pathos

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truncation of terms II

• Embedded Character truncation can be used for
  variant spellings
• "select organi?ation" -gt organization
  organisation 
• "select fib??board" -gt fiberboard fibreboard 
• This truncation feature is also useful for
  searching for unusual plural forms
• "select wom?n" -gt woman women
• Apparently you can also do prefixes by putting
  the ? in the beginning.
• "?mobile" -gt automobile metamobile

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use of connectors

• Connectors are used to put several words
  together.
• One instance where this is useful is when you
  have words that on their own mean different
  things.
• For example "mate" is a herbal beverage consumed
  in South America. Looking for mate on the
  Internet retrieves a lot of singles' pages.

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example terms related to "mate"

• What other terms to be used?
• matear (drink mate)
• matero (mate drinker)
• cebar (prepare mate)
• cebador (mate preparer)
• yerba (mate herb)
• bombilla (mate straw)

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connectors I

• '(W)' requires terms to appear one after the
  other next to each other e.g. 'yerba(W)mate?'
  matches "yerba mate".
• '(i W)' where i is an integer, means followed by
  at most i words, e.g. 'ceba?(3W)mate?' matches
  "cebar un maravilloso mate" but not "cebador
  guapo mirando un buen mate"

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connectors II

• '(N)' requires terms to be next to each other
  e.g. 'yerba(N)mate?' matches "yerba mate" or
  "mate yerba".
• '(i N)' where i is an integer, means proximity by
  at most i words, e.g. 'ceba?(3N)mate?' matches
  "cebar mate" or "matear con la cebadora".
• '(S)' searches for the occurrence of connected
  terms in the same paragraph.

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using Boolean operators

• In your query, you can combine several
  expressions with Boolean operators
• Example "S LIBRARY(W)SCHOOL? AND
  DISTANCE(W)EDUCATION"
• But I usually do not issue such fancy queries.

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executing several searches

• There can be several searches done sequentially,
  and the results sets are saved by the system.
• Each time the system assigns a set number, Si,
• These can be combined in Boolean expressions,
  e.g. 's S1 or S2 and S3'
• Remember that Boolean operations are
  set-theoretic!

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Boolean operators on sets

• When using Booleans, be aware that "and" has
  higher precedence than "or".
• Thus
• a or b and c
• is not the same as
• (a or b) and c
• but it is
• a or (b and c)
• Use parenthesis when in doubt

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DS (display sets)

• This command can be executed any time to review
  the sets that have been formed since the last B
  (begin) command.
• This can be useful to review your search history.

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the target command

• "target set" where set is a search result set
  creates a subset of the "statistically most
  relevant results" in the original set.
• I have not seen details about how this subset is
  computed.
• A new result set is being formed.

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display the type command

• type set/format/range
• set is a result set
• format is a format
• range can be
• start end
• start is a record number to start
• end is a record number to end
• all

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standard delivery formats

• 2 -- full record except abstract
• 3 or medium citation
• 5 or long full except full text
• 6 or free title and dialog number
• 8 or short title plus indexing terms
• useful to find other indexing terms
• 9 or full everything
• KWIC or K keywords in context

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options for delivery

• I once tried to email results to me, to no avail
• You can save the html of the search results in
  the browser.
• You can print the results within the browser.

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http//openlib.org/home/krichel

• Thank you for your attention!

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• to do set up consistent notation