Boolean Logic

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Boolean Searching




many search engines allow complex search queries, or advanced searches, which use special connecting words and symbols called Boolean operators

the English language uses syntax, a special set of rules, for combining words to form grammatical sentences

search engines use Boolean logic, a special mathematical syntax, to perform complex searches

boolean searching refers to a process of identifying those items that contain a particular combination of search terms

Boolean operators instruct the search engine how to interpret your search and expand, narrow, or restrict your search results

it is used to indicate that a particular group of terms must all be present (the Boolean AND)

that any one of a particular group of terms is acceptable (the Boolean OR)

or that if a particular term is present, the item is rejected (the Boolean AND NOT)

most search search engines provide a syntax and don't require you to use these terms because they have menus like the one below

if you choose "all the words" option from a pull-down menu, you are requesting the Boolean AND

if you choose the "any of the words" option, you are requesting the Boolean OR

if you want some words but not in combination with others, you are using the Boolean AND NOT

all search engines have full Boolean capabilities

below is an image form the advanced search feature of Google

searchengineboolean.png
many search engines automatically imply the AND so that Prague economics tourism is actually Prague AND economics AND tourism


boolean.png

Sources:

ADAM: Boolean Search Tips
http://adam.ac.uk/info/boolean.html

The Boolean Machine
http://kathyschrock.net/rbs3k/boolean/

Boolean Searching on the Internet
http://www.internettutorials.net/boolean.asp

Boolean Logic
http://www.ithacalibrary.com/sp/subjects/guide.php?subject=boolean

Boolify**
http://www.boolify.org/

Barker, Donald I. and Carol D. Terry Internet research Boston, MA: Course Technology, 2009

Hock, Randolph The extreme searcher's Internet handbook: a guide for the serious searcher Medford, NJ: CyberAge Books, 2009