LIS618 lecture 5

1
LIS618 lecture 5

• Thomas Krichel
• 2003-02-26

2
structure

• operations on any file (database)
• connectors
• booleans
• set handling
• display
• file-specifics
• bluesheet
• Introduction to structured queries

3
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.

7
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.
• 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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Looking at database structure

• Up until now, we have looked at commands that
  take a full-text view of the database.
• Such commands can be executed for every database.
• If we want to make more precise queries, we have
  to take account of database structure.

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blue sheet

• each database name is linked to a blueish pop-up
  window called the blue sheet for the database
• This is called the bluesheet.
• It contains the details of the database.

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closer look at the bluesheet

• file description
• subject coverage (free vocabulary)
• format options, lists all formats
• by number (internal)
• by dialog web format (external, i.e.
  cross-database)
• search options
• basic index, i.e. subject contents
• additional index, i.e. non-subject

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basic vs additional index

• the basic index
• has information that is relevant to the
  substantive contents of the data
• usually is indexed by word, i.e. connectors are
  required
• the additional index
• has data that is not relevant to the substantive
  matter
• usually indexed by phrase, i.e. connectors are
  not required

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search options basic index

• select without qualifiers searches in all fields
  in the basic index
• bluesheet lists field indicators available for a
  database
• also note if field is indexed by word or phrase.
  proximity searching only works with word indices.
  when phrases are indexed you don't need proximity
  indicators

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http//openlib.org/home/krichel

• Thank you for your attention!