Boolean Searching:
A Brief Introduction
Michael P. Sauers
What is Boolean?
- A system of logical operators devised by English mathemetician George Boole (1815-1864).
- A method for defining what you are, and are not searching for by placing a
combination of "operators" along with your keywords.
- Supported by online databases and most Web-based search engines.
Boolean Operators
- AND
- OR
- NOT (AND NOT)
- Operators do not need to be typed in all capitals. This is traditionally done to make them easier to separate visually from your keywords.
AND
- Specifies that both terms must appear within a result.
- Terms may appear in any order.
- In most cases, AND is the default operator.
OR
- Specifies that either term must appear within a result.
- Term order is irrelevant in this circumstance as only one term may appear and still satisfy the search request.
NOT (AND NOT)
- Specifies that the first term must appear and the second term must not appear
- Term order is relevant in this instance as you are specifying only one term actualy appear in a result.
"quotation marks"
- Conntects multiple words together as a phrase.
- Forces the search engine to search for multiple words in the order specified.
- Although not actually a Boolean operator, quotation marks are extemely useful when searching.
Venn Diagrams
- A method of visually depecting boolean logic developed by British logician John Venn (1834-1923).
war
Image courtsey of boolistic.com
iraq
Image courtsey of boolistic.com
iraq OR war
Image courtsey of boolistic.com
iraq AND war
Image courtsey of boolistic.com
"iraq war"
Image courtsey of boolistic.com
iraq AND NOT war
Image courtsey of boolistic.com
EBSCO Host
- Let's try each of these searches in EBSCO and see what sort of results we receive:
- war
- iraq
- iraq OR war
- iraq AND war
- "iraq war"
- iraq NOT war