Boolean Techniques

Boolean searching implements the rules set by Boolean logic. Boolean is a form of math and the rules of this math type apply to Boolean searches. Below are some examples of how you may implement Boolean logic in database/Internet searches to locate information more efficiently and quicker.

Boolean Searching

Logical operators are used as search parameters:

 AND

Search for documents containing all terms/words. Search for and match all terms. AND sometimes is represented by a  "+" symbol in some search tools. Most search engines support the + symbol for AND.

 Examples:

• pear AND apple

• cat AND dog AND pet

• soren AND kierkegaard AND philosophy AND existential

OR

Search for documents containing either of the words and match any search term. OR can be represented as ANY in some search tools. Some search tools do this search type by using a menu next to the search box or on the advanced search page. Most search tools list pages having all terms first, and then those with some of the terms.

 Examples:

• pear OR apple

• cat OR feline

• gun OR weapon OR pistol OR rifle

NOT

Exclude terms and allow searching for documents containing the first word before NOT but not the second word. Most search tools allow excluding certain words. The "-" symbol is sometimes used to represent NOT.

 Examples:

• pear NOT apple

• cat NOT dog

• marx NOT groucho

• cat NOT dog NOT canine

NEAR

Proximity control command used to specify how close terms should appear to each other. The exact distance desired between words can be specified by using the NEAR/# command. For example: "fruit NEAR/10 apple" specifies fruit should be no more than ten words away from apple. The default word distance varies among search tools. Usually a seven to ten word distance is the default.

 Examples:

• fruit NEAR apple

• groucho NEAR marx

• shakespeare NEAR macbeth

Nesting ( )

Nesting is used to form more complex queries and most search tools support this feature. Queries are nested using parentheses. Nesting via parentheses allows combining different Boolean query types to be applied in a particular order. When using nested parentheses, there must be the same amount of left parentheses as there are right parentheses. In other words, the number of parentheses on both sides must balance.

Examples:

• fruit AND (apple OR orange)

• (fruit AND juice) AND apple

• fruit AND (apple OR orange) AND juice

• (fruit AND juice) AND (apple OR orange)

• ((fruit AND juice) AND (apple OR orange)) AND NOT banana

Additional Boolean Search Techniques

Phrase Searching/Quoting

Quote marks define the phrase so words are retrieved in the exact order typed. Quotes are used to limit the number of responses retrieved and to ensure that the exact concept you are seeking is found.

 Examples:

• "chinese food"

• "groucho marx"

• "to be or not to be"

• "seven brides for seven brothers"

Truncation/Stemming/Wildcards

Truncation, or stemming, expands the number of responses, and is used to replace none, one or more letters at the end of a word. Usually an * at the end of a word or part of a word will retrieve all forms of the word.

Be very careful when using truncation. It can return an unmanageable number of results. Use truncation for less common word root stems and don't use this for word roots that form the base of many common words.

 Examples:

• librar* retrieves: library, libraries, librarians and librarianship.

• cit* retrieves city, cities, citrus, citroen, etc.

• cat* retrieves cat, catty, cathy, catamount, cathedral, etc.

Other Power Searching Techniques

Search engines have various means such as menu systems and special query commands to refine and control searches. Each search tool has some operator or technique that is unique to it. Be sure to read the "Help" function of the search tool you are using to find out more.