Boolean logic is a system of showing relationships between sets by using the words AND, OR, and NOT. (The term Boolean comes from the name of the man who invented this system, George Boole.) Boolean logic is recognized by many electronic searching tools as a way of defining a search string.
Boolean searching is an important tool that can be used when searching catalogs, indexes, online databases, and the web.
Here are some examples of boolean search strings:
Boolean logic is a bit more confusing than it seems. Sets get smaller the more "AND" is used, and larger the more "OR" is used. Although you might think "AND" would add more hits to a set, what it has actually added is limitations. The term "OR" adds possible options. A good way to illustrate how boolean logic works is through a Venn diagram. The circles in a Venn diagram illustrate different sets and the shaded areas show how the boolean terms form relationships between the sets.
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