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

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• 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.

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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

GOOGLE

• 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

GOOGLE

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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