Boolean Operators

Help: Research Tools: CU Library Catalog: Advanced Search Features:

Using Boolean Operators

Boolean, or logical operators -- AND, OR and NOT -- broaden or narrow a search by defining the relationship between terms, or sets of terms.

Using Boolean operators in a Command Keyword search:

Using the AND operator between two or more terms narrows the search results to records that contain both or all of the terms.
e.g. vietnam AND history
Using the OR operator between search terms broadens the search to retrieve records that contain either, or any, of the terms.
e.g.encyclopedia OR dictionary
The NOT operator instructs the system to exclude a certain term from the search results.
e.g. worms NOT computer

Nesting Commands in a Command Keyword search:

For more complex queries combining different Boolean operators, use parentheses ( ) to ensure that the operations are performed in the correct sequence.

e.g. (vietnam and history) and (dictionary or encyclopedia) to retrieve records containing (vietnam and history and dictionary), OR (vietnam and history and encyclopedia)

Additional Command Keyword Examples:

politics AND (athens OR sparta)
(residence OR home OR housing) AND (elderly OR aged)
((color OR colour) AND (impressionist OR impressionism)) NOT (monet OR manet)

Guided Keyword Search:

The Guided Keyword Search guides a user through the process of combining terms and nesting operations:

Enter terms in the first line. Note that the pull-down to the right is set to [all of these] by default. This instructs the system to place an AND between each term.

Or, enter terms and select [any of these] from the pull-down menu. This instructs the system to place an OR between each term.
Use the radio buttons for AND, OR, and NOT between lines to set relationships between sets of terms. See the sample Guided Keyword Search below:

Boolean Operator Guided Keyword Equivalents Command Keyword Examples Results

AND

AND with next set

all of these

business AND ethics

"human genome project" AND disease
poet? AND sonnet? AND lyric?
Retrieves records that contain ALL of the search terms.
Narrows a search.

OR

OR with next set

any of these

sixties OR 60s OR 1960s

theater OR theatre
web OR www OR "world wide web"
Retrieves records containing ANY of the search terms.
Expands a search.

NOT

NOT with next set

java NOT indonesia

"organic compounds" NOT polymer?
Excludes records containing the second search term.
Focuses a search.