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Boolean Searching

Boolean logic is basic to searching. It is the process of narrowing or expanding a search by linking search terms with the connectors or operators:

  •  AND

  •  OR

  • NOT

  •  and sometimes NEAR

It refers to the logical relationship among search terms and is named after British mathematician, George Boole.

Be sure to use capitals when typing your operators.

Operator

Function /Action

Example

AND

Both words must be present in the search results (not necessarily in the order they appear.) It narrows a search. Use it to combine two ideas which must be present

London AND travel

Violence AND classroom

Child AND abuse

Crime AND poverty

OR

Either word should be present. Use it combine synonyms or related terms. It broadens a search

College OR university

Adolescent OR teenager

Sex OR gender

NOT

Narrows a search by excluding words or phrases.       A word should not be present in the search results. Use it with caution since items can be easily eliminated. It is most useful when there are alternative meanings of a word.

travel NOT luxury

cats NOT musicals

cancer NOT mice

lotus NOT program

NEAR

Used to specify how close terms should appear to each other.

Moon NEAR river

" "

Searches for a whole phrase in the order it appears.

"LondonUnderground"

+ or -

"+" is sometimes used to mean AND.

"-" is sometimes used to mean NOT.

London + travel - luxury

 

*

Can be used as a wild card to return words that include all or part of the word. (Some sites do this automatically.)

London AND travel* Returns London travel, traveler,       traveling, etc.

( ) nesting

Allows the building of complex queries. By combining operators a search can be fashioned for a very specific topic. This is done by nesting, or placing certain terms in parentheses, or by creating number sets.

(hogs or pigs) and market

(sex or gender) and pay

(cancer and fat) not mice

Where to Search: A Selected List

Boolean Commands

Command

How

Supported By

Or

OR

All but...

None

Google, Go, LookSmart, Yahoo

And

AND

All but...

None

Google, Go, LookSmart, Yahoo

Not

NOT

All but...

AND NOT

AltaVista, Excite, MSN Search, Netscape, Snap

None

Google, Go, LookSmart, Yahoo

Nesting

( )

All but...

None

Google, Go, LookSmart, Yahoo

Near

NEAR

AOL Search (specify number) AltaVista & MSN Search         (10 words), Lycos (25 words), WebCrawler (2 words)

None

Others

The following Internet sites are helpful to learn more about Boolean searching:

Boolean Searching:  http://searchenginewatch.com/2155991

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

HELP: Boolean Searching: http://media.lbcc.cc.ca.us/doc/BOOLEAN.HTX