English mathematician George Boole (1815-64) founded a field of mathematical and philosophical study called symbolic logic. His name is now used most often to describe a set of logic commands used with search engines called Boolean commands .

These Boolean commands must be entered in capitals combined with keywords and key phrases.

There are three Boolean commands that we will be discussing today. They are the "AND", "OR" and "NOT" Boolean commands .

• AND - when entering combinations of keywords and keyphrases as search criteria, the search engine will find web documents containing both terms. For example - "chocolate cake" AND pies will give you web documents containing both of those terms. Sometimes the Boolean command may not work in the search engine you are using. You can try to substitute the plus sign + without a space between the keyword and key phrases. For example - "chocolate cake"+pie.

• OR - when entering combinations of keywords and key phrases as search criteria, the search engine will find web documents containing either one term or the other term. For example - "chocolate cake" OR pies will give you web documents that will contain either "chocolate cake" or pies. If the Boolean command OR does not work with your search engine, then use the commas to separate the keyword or key phrases.

• NOT - when entering combinations of keywords and keyphrases as search criteria, the search engine will find web documents containing the term before the NOT and excludes the term following the NOT. For example - "chocolate cake" NOT nuts will find all web documents containing chocolate cake and exclude the word nuts. Again if the Boolean command NOT does not seem to work in your search engine, use the minus sign - without a space between the keyword and key phrases. For example "chocolate cake"-nuts should work.

Now there is a way to "Nest" Boolean commands to give very specific results. This is a combination of the OR and the AND Boolean commands for several search combinations. The OR Boolean commands should always be in parenthesis. () An example of nesting Boolean commands is ("chocolate cake" OR "vanilla cake") and (nuts OR raisins). This would give you web documents about chocolate or vanilla cake that have nuts or raisins. Another example of nesting Boolean commands is ("chocolate cake" OR "vanilla cake") AND NOT (nuts OR raisins). This would give you web documents about chocolate or vanilla cake with no nuts or raisins.

Remember you can normally substitute the plus sign for AND, the minus sign for NOT, and commas for OR. The more specific you get with requesting search information on topic, the better the results will be that you find exactly what you want.

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• () ValHaring - 27 Aug 2002
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