Search Strategies

Searching the Internet and Online Library Catalogues

It is possible to construct some complex searches using Boolean logic.  This technique works equally well with online library catalogues and internet search engines.
To do so, use the following terms: AND, OR & NOT. 
Boolean logic provides a simple and elegant way to construct a "search expression" with which to find precisely the information you need.
 
How Boolean logic works is represented by the following diagrams:


This is expressed as yellow AND red, drawing AND figure
When using AND the results retrieved will contain information from both the yellow and the red circles indicated here by the brown oval in the middle. The results will not include those documents containing ONLY yellow or ONLY red information In this example a search for drawing AND figure should retrieve ONLY those records containing BOTH keywords, that is, books, articles or web sites about figurative drawing.

 
This is expressed as Yellow OR red, monoprint OR collograph
When using OR the results retrieved will contain either yellow information, OR red information, OR red and yellow information together (middle brown area). In the diagram the documents retrieved by using this search expression are contained within ALL the colour areas. For example a search for monoprint OR collograph will retrieve records containing each of these keywords in addition to those containing BOTH.

This is expressed as Yellow NOT Red, sculpture NOT stone
When using NOT, results will contain only the yellow area. The NOT operator will exclude red completely and the brown area in the middle will also be eliminated. The NOT operator should be used carefully as it can exclude some potentially useful
information. For example if you typed sculpture NOT stone in order to eliminate all books or articles on stone sculpture you would retrieve records containing the word sculpture but NONE containing the word stone. You could lose many useful books
articles or web sites such as those on wood or metal sculpture if they were also PARTLY about stone sculpture.