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Research Tips & Peer Reviewed Articles: Boolean Searching with AND and OR

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What does "Boolean" mean?

George Boole was an English mathematician who lived from 1815 to 1864. He developed a branch of algebra that works with sets. When you type search words in one of the Library's online databases, you can use his "operators" AND, OR, (and sometimes NOT) to tell the computer (1) to make a set of results for each search term and (2) how you want the computer to combine the sets to give you the best results.

Arranging your search words with Boolean operators

Two very important little words are: AND and OR.

AND: This tells the computer that all your keywords have to be present in the search results. 

Topic

Keywords in Topic

Search Statement

What are some ways to save energy at home?

Save, energy, home

Save AND energy AND home

What was the cause of the recession?

Cause, recession

Cause AND recession

Are there advantages to being bilingual?

Advantages, bilingual

Advantages AND bilingual

Here’s another way to look at this: Draw yourself a diagram with each search term in a circle. For this example of the search for advantages AND bilingual, one circle represents all the articles in a database that contain the word “Advantages”.  The other represents all the articles in a database that contain the word “bilingual”.  Draw them overlapping. The part that overlaps represents the articles that contain both words.

OR: This tells the computer to also look for synonyms or related words.  Use parentheses to group the related words. This will expand your search.

Topic

Related Words for Topic

Search Statement

What are some ways to save energy at home?

Save: reduce, cheaper, green

Energy: power, heat, electricity

Home: house

(save OR reduce OR cheaper OR green) AND (energy OR power OR heat OR electricity) AND (home OR house)

What was the cause of the recession?

Cause: start, started, “set off”

Recession: downturn, “economic conditions”

(cause OR start OR started OR “set off”) AND (recession OR downturn OR “economic conditions”)

Are there advantages to being bilingual?

Advantages: advantage, benefit, benefits

Bilingual: “second language”, “two languages”

(advantage OR advantages OR benefit OR benefits) AND (bilingual OR “second language” OR “two languages”)