Madigan Library
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Applying Boolean Logic
Computers organize sets of keywords. Use "And, Or, or Not" to control the results you want. For example, think of the concept chocolate, and the concept cake.
AND
Search the word chocolate and the word cake: "chocolate and cake".
Both words have to be in the document found. Results: documents about "chocolate" and about "cake". Be careful: a document could also be about chocolate icing on a white cake. Both words are inside the document, but we didn't ask the computer to put the words right next to one another.
The gray would be the outcome of the search for "chocolate and cake".
OR
Search the word chocolate and the word cake: "chocolate or cake".
Either the word chocolate or the word cake must be in the document found. It makes no difference which word is found. Results: documents about "chocolate covered ants, chocolate cake, chocolate Labradors, chocolate candy, carrot cake, angel food cake..."
The blue would be the outcome of the search for both "chocolate or cake".
NOT
Search the word chocolate and the word cake: "chocolate not cake".
I do not like cake, so...search the word "chocolate" but do not give me any documents about cakes! Only the word "chocolate" needs to be in the document found. Results: chocolate icing, chocolate candy, but not chocolate cake!
The light gray would be the outcome of the search for "chocolate not cake".