Boolean Searching

More than one concept, single search term

If you want to find information which discusses both concepts, connect the search terms with the Boolean connector "and". For example, search using the statement:

Alzheimer’s and aluminum

Each additional search term connected with an "and" will result in fewer pages retrieved.

Only one concept, more than one search term

Connect the search terms with the Boolean connector "or". For example, search using the statement:

aluminum or aluminium

will find information containing the word aluminum or the British word aluminium or both words. Each additional search term connected with an "or" will result in a larger number of pages retrieved.

Eliminating a Concept

In some cases you may wish to eliminate a concept from your search. This is possible by providing Boolean "not" capability. If you want information which discusses Alzheimer’s, but does not mention aluminum, you may use the following search statement:

Alzheimer’s not aluminum

Complex Boolean Information: Nested Logic

Complex Boolean information needs meet both of the following criteria:

• There is more than one important concept in the statement of information need.
• At least one of these concepts can be expressed by more than one search term.

The following is a statement of a complex Boolean information need:

I want to find information on the role of aluminum (both American and British spellings) in Alzheimer's disease.

The proper Boolean search statement is illustrated by the following:

alzheimers and (aluminum or aluminium)

Note especially the use of the parentheses. The parentheses tell the search engine or box to "Process the terms within the parentheses first". This is absolutely necessary for proper processing of combined AND's and OR's. If the parentheses are omitted, many search engines will process the statement left to right, resulting in retrieval of all pages with both Alzheimer’s and aluminum, PLUS all additional pages with aluminium, which is not what you want.