Search/Browse Help - Boolean Operators and Nesting
Boolean Operators and Nesting
Boolean operators and nesting help you search for combinations of words or phrases processed in a specified order. Boolean operators are supported in Advanced Search and the EXPERT option of Keyword Search. Keyword (EXPERT) also supports nesting. In the LC Catalog, Boolean OR expressions are executed first, followed by expressions using AND or NOT (which are considered equivalent). Processing of equivalent expressions takes place in a left-to-right (or top-to-bottom) sequence.
Boolean operators AND, OR, and NOT can be searched as keywords. In Keyword Search, just enter these terms in the search box. In Keyword (EXPERT) search, include these terms, along with other words, in quotes as a phrase. Boolean operators can be entered in either upper or lower case.
| Concept | Search terms | Retrieval formula |
|---|---|---|
| AND | rodgers AND hammerstein children AND poverty "civil war" AND virginia |
 Retrieves only records containing all terms. |
| OR | sixties OR 60s OR 1960s labor OR labour email OR e-mail OR "electronic mail" |
 Retrieves records containing one or more terms. |
| NOT | caribbean NOT cuba jockey NOT disc "civil war" NOT american |
 Excludes records containing the term associated with NOT. |
| NESTING | fruit AND (banana OR apple) (women OR woman) AND basketball ((color OR colour) AND (decorate OR decoration)) NOT (art OR architecture) |
For the greatest precision, use parentheses ( ) to group portions of complex Boolean expressions in the EXPERT option of Keyword Search. Terms inside parentheses are processed first. |