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Ask About Boolean Searches

by Boggled in Beloit | May 26, 2012

Subject :Internet

Dear Toolkit,

When I'm looking for information on the Web, some search engines ask if I want to do a "Boolean search." Maybe I would if I knew what the heck it was! Can you shed some light on this cryptic conundrum?

Boggled in Beloit

Dear Boggled,

Let me introduce you to George Boole, a math whiz born in England in 1815, the year Napoleon was being hassled at Waterloo. George was the son of a shoemaker who couldn't afford to send him to Oxford or Cambridge, so young George educated himself for the most part. This self-taught scholar was an expert linguist, a teacher, an aspiring clergyman and a father of five daughters. His bride was the niece of George Everest, for whom that notable mountain is named. But his main claim to fame is a form of symbolic logic, later christened Boolean algebra, in which there are only two ultimate values--true or false.

Boole was a contemporary of a couple of other 19th century English pioneers of computer science. Charles Babbage was busily developing an "analytical engine," the ancestor of the digital computer of today, just about the time George was defining his logic. And Ada Byron King, Countess of Lovelace and daughter of the poet, Lord Byron, worked closely with Babbage on what the public of that era deemed his greatest folly. Ada is thought to be the first computer programmer. She theorized that punch cards, used in weaving intricate designs on Jacquard looms, could be employed as the "software" to give life to Babbage's "hardware." And she might have pulled it off had she not died at the tender age of 36. But IBM sure liked her idea!

When computers finally got themselves more fully developed in the mid-20th century, they were based on the binary number system in which each and every bit has one of only two values--zero or one. (The proverbial switch--on or off--signified by a difference in voltage!) In 1938 an MIT grad student, Claude Shannon, noticed that George's true/false logic system fit nicely with computer science's 0/1 binary bent. Thanks to Shannon, Boole's logic was discovered to be the most sensible way to sift through vast amounts of computer-based data and the Boolean search was born.

Boolean logic uses punctuation and prepositions to narrow a search. By using the mundane words AND, OR and NOT, and sometimes NEAR, as operators, and occasionally quotation marks or brackets, wheat generally emerges from chaff. Since a picture is said to be worth a thousand words, take a look at this site for a graphic representation in living color of how Boolean logic narrows down a search.

This link will save several dozen paragraphs of confusing descriptions about overlapping circles or boxes and it will give you a pretty standard illustration of the classic diagrams dreamed up by John Venn, another Boole peer, representing the AND, OR and NOT logic concepts.

As a rule, AND trumps OR, so you may need to use parentheses to clarify the search:

A or B and not C or D might be read as:
A or (B and not C) or D unless you specify
(A or B) and not (C or D)

Some engines allow the use of quotation marks in place of brackets. And some engines will let you do "proximity searches" using the operator NEAR. For example: mortality AND (auto NEAR crash) may give you a list of hits on car accident survival statistics where the word auto is not necessarily always exactly adjacent to the word crash.

Wasn't that enlightening? Now that you've got a grip on how that's done, let's go over a few more tips for successful searching.

Internet has been likened to a library after an earthquake. All the books are still there, but they're scattered all over the floor. And if the card catalog survived the quake, you'd at least be able to tell what part of the library your book was in, if not the shelf it used to be on.

A search engine is like a card catalog. It can give you a general sense of direction, and the more you can tell it, the more it can tell you about how to locate the information you need in the gigantic database that is the Internet.

But all search engines are not created equal. Google is my personal favorite. It's an industrial-strength, keyword-based search engine with both simple and advanced (Boolean) options, and it's fast and getting better every day. I'm not alone in my opinion -- Google has over 80 percent of the search engine market share.  Bing and Yahoo are far behind, in second and third place, each with under 10 percent.