Contents
•Boolean Logic
•Truncation
•Phrase Searching
theTHEORY Boolean Logic
• Boolean logic allows users to combine search terms.
• Boolean logic allows users to both expand or limit their search.
• This is achieved by using Boolean operators AND, OR and NOT to link the search terms in searches.
• Boolean logic is used by search engines on the Internet and some CD ROMs.
Boolean Logicthe
THEORY
• An example will explain how the operators (or link words) work to limit or expand your search.
• The question for this search is:
How are children affected by television?
Boolean Logicthe
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• First it is necessary to isolate the major terms from the example to use as search terms.
• These terms are referred to as key words.
• E.g. The keywords from this example are CHILDREN and TELEVISION.
Boolean Logicthe
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• The first operator (or link word) to investigate is OR
• How will it affect the search on children and television?
• Will the search expand or will OR limit the search?
Boolean Logicthe
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• Type in “children OR television”
• Documents retrieved have either of the key words on them.
Boolean LogicUsing
OR
ORHighestretrieval
Television & children
• The second operator (or link word) to investigate is AND
• How will it affect the search on CHILDREN and TELEVISION
Boolean LogicUsingAND
• Type in “children AND television”• Items retrieved only where children
and television both appear on the pages.
Boolean LogicUsingAND
Television & children
ANDnarrows the
search
• The third operator (or link word) to investigate is NOT
• How will it affect the search on CHILDREN and TELEVISION?
Boolean LogicUsingNOT
• Type in “television NOT children”• Items retrieved refer to television
only.
Boolean LogicUsingNOT
Items on
television
NotPages contain
one but not
the other term
• Search engines require users to click on advanced search to use boolean searching.
• Individual engines use boolean slightly differently.
• The example of how Alta Vista uses boolean logic will explain further.
Boolean LogicUsing
ALTA VISTA
• Boolean searching with search engine Alta Vista requires the + (plus) symbol to be placed before all terms if they are to be included. (+ replaces AND)
• E.g. +china +platewill result in both terms being somewhere in all documents retrieved.
Boolean LogicUsing
ALTA VISTA
Try it : http://www.altavista.com/
• Boolean search with Alta Vista requires the – (minus) symbol to be placed before terms which are to be excluded. (- replaces NOT)
• E.g. china –plates retrieves all documents with China but excludes documents containing plates.
Boolean LogicUsing
ALTA VISTA
Try it : http://www.altavista.com/
• Truncation is a tool which can broaden a search.
• Users enter part of a word in order to ensure retrieval of all documents containing variations of the word.
• Try the next examples using Alta Vista.
TruncationUsing
ALTA VISTA
• Tool to broaden searches1.Right hand truncation with*• Type sight*• You will retrieve documents with
sights, sightseeing, sighted etc.
Try it: http://www.altavista.com/
TruncationUsing
ALTA VISTA
2. Internal “wild-card” truncation with*
• Type colo*r
• You will retrieve documents containing both colour and color.
• Try it: http://www.altavista.com/
TruncationUsing
ALTA VISTA
• Phrase searching offers another tool which will contribute to a successful search on the Internet.
• Try the following examples -
Phrase SearchingUsing
• Enclose terms to be searched as a phrase in quotes
“children’s book week”“The capital city of India”
• The phrase will be retrieved exactly as keyed in.Try it: http://www.google.com/
Phrase SearchingUsing
References
•Henninger, M. (1999). Don’t Just Surf. Effective research strategies for the net. University of New South Wales Press Ltd., Sydney.
Tyner, R. (1999). Internet Search Tools & Techniques. M.L.S.Okanagan University College. Available from http://www.sci.ouc.bc.ca/libr/connect96/search.htm
Barlow, L.(1996-1999). The Spider’s Apprentice: A Helpful Guide to Search Engines. Monash Information Services. Available from: http://www.monash.com/spidap4.html
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