Search Engines and Algorithms: Semantic Search - Boolean Search and Wildcard Search

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Boolean Search

A Boolean Search is a combination of terms allowing the inclusion or exclusion from search results of documents containing certain words. This is achieved through the use of operators such as AND, NOT and OR.

Boolean operators consist of the following words, and how they are used:

• AND or the plus (+) sign - Two or more terms or phrases must be in the description; AND is the default operator.

• OR - Either one or the other of the multiple terms specified must be in the description.

• NOT or the minus (-) sign - A term or phrase specified is excluded from the search

Boolean Search is probably the most simple of search matching programs. A good example of a Boolean Search is when you use any of the major search engines like Google or Yahoo with multiple words; it is assumed that the operator AND is being used, in order to search for all the terms. For example, if I perform a search with the phrase: buy plasma TV online, it is assumed that I am looking for all of the words to match my query, and all pages that contain the words buy, plasma, TV, and online will be returned.

Another example would be if I wanted to exclude a search term during my search: buy plasma TV online -Sony now the search algorithm understands that all the relevant results will be returned that include the words buy, plasma, TV, and online, but exclude the pages that contain the word Sony.

It is rare that you will find search engines that do not support Boolean search, and most do it automatically, without your having to enter the Boolean operators. There is once in a while you’ll find a search where Boolean searches aren’t performed automatically. One I used recently was a forum search, in which I had to use the (+) sign in order to have all of the results included, so while this search supported Boolean search, it just wasn’t automatic.

Wildcard Search

Many advanced search engines allow for Wildcard Searching. Wildcards, usually in the form of an asterisk (*) or a question mark (?), are used to substitute for possible letters to make up the spelling of a word.

The single character wildcard search looks for terms that match with the single character replaced. For example, to search for text or test you can use the search: te*t or te?t.

Next: Proximity Search and Fuzzy Search >>
 

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