Lesson 2: Boolean Searching

The library catalog is searched using what are known as "Boolean operators".  These operators are AND, OR and NOT.   When you search the catalog using more than one keyword, you must combine your keywords with one or more of these operators. 

• AND

  • This operator will narrow your search when placed between keywords.  For instance, if you are looking for books about the possible evolution of birds from dinosaurs, you would type the phrase birds AND dinosaurs in the search box.  This will return a list of book records that have both of your keywords somewhere in the record.  Most of the books in the results list should have something to do with the avian evolution.  Please note:  AND is the default operator for this catalog.  You can type AND in between your keywords, but it is not necessary.  If you do not use an operator between keywords, the catalog will default to AND.

• OR  

  • This operator will broaden your search.   For example if you are looking for books on birds or books on dinosaurs you would place the OR operator between your search terms.   You would then type the phrase birds OR dinosaurs into the search box.  The OR operator is also useful when you want to search using synonyms (words that mean the same thing, for example, car OR automobile) or words that have variant forms.

• NOT  

  • This operator will restrict your search.   NOT allows you to eliminate a term from your results.  For instance,  say you are searching for Martin Luther the monk who began the Reformation.  You type in Martin AND Luther in the search box, click on the search button, and view the resulting list of books.  You quickly see that the computer has retrieved books on both Martin Luther the monk and Martin Luther King the civil rights leader.  To remove any books about Martin Luther King, you place the NOT operator before the word you wish to eliminate.  In this case, King.  Your search phrase now looks like this:    Martin AND Luther NOT King.  If you do the search again, you will find that the computer has returned only books on Martin Luther the monk.  NOT is a very useful and powerful operator that can help to refine your search.  However, it must be used carefully.   In the above search you are asking the computer to remove any record with the word "king" in it.  This means that a potentially useful book on Martin Luther by someone with a name such as "John King" would not be retrieved. 

Truncation

You may use what is known as the truncation symbol (*) to include varying forms of a word in your search.  For instance, instead of looking for birds AND dinosaurs you could truncate birds to bird* and dinosaurs to dinosaur*.  This way your search would include the word bird, birds, birding, dinosaur, dinosaurs, dinosaurian etc.   If you do not use the truncation symbol the computer will only search for the exact words birds and dinosaurs.  By searching for all forms of the word, you increase your chances of finding relevant books.

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