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LIS618 lecture 1

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retrieves all words that begin with path: paths, pathos, pathway, pathology ... Each time the system assigns a set number, Si, ... – PowerPoint PPT presentation

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Title: LIS618 lecture 1


1
LIS618 lecture 1
  • Thomas Krichel
  • 2003-09-20

2
Structure of talk
  • Recap on Boolean
  • Before online searching
  • Working with DIALOG
  • Overview
  • Search command
  • Bluesheets
  • Basic and additional index

3
before a search I
  • what is purpose
  • brief overview
  • comprehensive search
  • What perspective on the topic
  • scholarly
  • technical
  • business
  • popular

4
before search II
  • What type of information
  • Fulltext
  • Bibliographic
  • Directory
  • Numeric
  • Are there any known sources?
  • Authors
  • Journals
  • Papers
  • Conferences

5
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?

6
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

7
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

8
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"

9
Substeps in the second step
  • Identify search terms
  • Use Dialog basic commands to conduct a search
  • View records online or print the results

10
the 's' (select) command
  • Once issued the "begin" command to select a
    database, we issue the "s" command on the
    database.
  • "s query_terms" where query_terms are the query
    terms
  • 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.

11
connectors
  • If you want to use several keywords there are
    three ways
  • you can truncate search terms
  • you can build an 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

12
truncation of terms
  • 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

13
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
  • You can also do prefixes by putting the ? in the
    beginning.
  • "?mobile" -gt automobile metamobile

14
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.

15
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)

16
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"

17
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.

18
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.

19
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!

20
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

21
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.

22
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.

23
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

24
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

25
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.

26
http//openlib.org/home/krichel
  • Thank you for your attention!
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