NESTING

Using two or more boolean operators in a search statement is another method which allows for more precise searching. This process is called NESTING. The items being combined must be placed within parentheses when you are using the NESTING option. Items within the parentheses are processed first. In the example:

(gun? OR firearm?) AND violence

the computer looks for articles which have the terms gun? or firearm? first. Once it has found those, it then begins to narrow your search by "ANDing" the results with the term violence. Another example would be:

(gun? AND violence) NOT school?

In this example the computer looks for information on guns and violence and then discards any that relate to guns and violence in schools.

Some people might find it easier to think of the nesting process in algebraic terms. For example, the search statement of
(gun? AND violence) NOT school?
could be translated into: (a + b) – y.

Another technique for greater search precision is the use of Double Nesting. If you have several qualifiers to define your topic, you could write a search statement such as the following:

((gun? OR firearm?) AND violence) NOT school?

In this case, the computer looks first for items with the terms gun? or firearm?, which would be a broad search. It then starts to focus or narrow the results by "ANDing" the term violence. After those results are found, the computer then goes a step further and eliminates any items which mention schools.