Internet expert Barbara G. Friedman calls Boolean expression “the real power of advanced search” and “the Web’s best kept secret.”
In her book Web Search Savvy: Strategies and Shortcuts for Online Research (Mahwah, NJ: Lawrence Erlbaum Associates, 2004), 28, Friedman explains that “Boolean logic is named for George Boole, a 19th-century British mathematician who merged algebra and logic which, for our purposes, determines the way information on the Internet is searched for and retrieved. Boolean logic allows the user to include operators (also called connectors or joiners) in a search to retrieve fewer and more meaningful results.”
Boolean operators, she says, are “and,” “or,” “not,” and “near,” and they work in the following ways:
“AND”
Putting AND between words in your search tells the search engine you want it to return links to documents containing both (or all) words together on a page. For example, the names Laurel and Hardy would naturally appear together on some Web sites, since the two were a comedy team. Typing laurel AND hardy tells AltaVista you want all documents containing the words laurel and hardy. You may get links to pages about the comic actors Stan Laurel and Oliver Hardy, but by using lowercase letters you’ll likely also get pages that make reference to bay leaves and hardy chrysanthemums. How might you narrow your search, then? Two options are worth trying. First, type your search using uppercase letters for the actors’ names…You could further minimize your search results by specifying language, a range of dates, or adding keywords that pertain to specific information.
“OR”
Using OR in your search strategy widens the results. Type sharks OR fish and you tell the search engine to find those pages containing either the word “sharks” or the word “fish. ” The words do not necessarily have to appear together on the page. This is helpful if you are searching for as many pages as possible.
“AND NOT”
Most search engines also let the user exclude things using the operator NOT, or in the case of AltaVista “and not.” For example, the search results for Truman AND NOT Roosevelt on the AltaVista page would include pages that refer to Truman but exclude those containing Roosevelt, even if those same pages also contained Truman’s name.
“NEAR”
You may be able to call up a Web site by a identifying a combination of words and their proximity to one another. Say, for instance, you are looking for a site related to the professional golfer Tiger Woods. His first and last names are likely to appear on a wide range of sites. “Woods” could be on pages related to forests or parks and “tiger” might appear on pages related to wildlife, for instance. To avoid those kinds of sites, you can use the NEAR function of a search engine. AltaVista allows the user to identify sites where words appear within 10 words of each other. By typing “Tiger Woods” NEAR golf, you are telling the search engine to find sites where the name Tiger Woods (remember that by placing it in quotation marks or parentheses and using capitalization, you are asking for an exact match) appears within 10 words of “golf.”
The NEAR operator is also quite helpful when you’re looking for a person. Since proper names on lists are sometimes indexed by last name, use NEAR to find variations on a name. For example, a search phrased as John NEAR Doe will find Doe, John, and John Q. Doe.
Friedman adds that “some simple searches allow some use of Boolean logic using the plus sign (+) for AND, and the minus sign (-) for AND NOT. However, simple searches do not offer the additional strategies discussed above.”
For more of Friedman’s online search strategies and shortcuts, click here.
