The Evolution of Search Engine Technology

One way to make Internet searches more effective was to use the Boolean system, named for George Boole, a nineteenth-century mathematician. The Boolean system is based on set theory: if you cross the set containing hot dogs with the set containing mustard with the set containing relish, you get a search that produces a hot dog with mustard and relish. A Boolean query is the kind that invites you to include the commands “and,” “or,” and “not,” and it had already existed as a way of querying a database. The Boolean system is famous for being counterintuitive: to get your above-mentioned hot dog as you ordered it, you actually have to specify mustard or relish. And, although it can be useful, it does not match the way most people think. But using the “advanced search” option in 2006 for Google, Yahoo!, or many other search engines, one is led into a more natural way of posing a Boolean query. Searchers can specify a whole phrase or phrases that they want to find plus words that must be included (the equivalent of “and”) and words that cannot be included (the equivalent of “not”).