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These include AND and OR and the unary operator NOT (). [3] The AND and NOT expressions are known as implied Boolean operators as they require or disallow a word or a phrase. [4] The use of + symbol as a prefix before a keyword requires that word be in a search result.
In computer science, a Boolean expression is an expression used in programming languages that produces a Boolean value when evaluated. A Boolean value is either true or false.A Boolean expression may be composed of a combination of the Boolean constants True/False or Yes/No, Boolean-typed variables, Boolean-valued operators, and Boolean-valued functions.
Like word searches and exact-phrase searches, non-alphanumeric characters are ignored, and proximity and fuzziness are options. insource:/regexp/ insource:/regexp/i: These are regular expressions. They use a lot of processing power, so we can only allow a few at a time on the search cluster, but they are very powerful.
Phrase search is one of many search operators that are standard in search engine technology, along with Boolean operators (AND, OR, and NOT), truncation and wildcard operators (commonly represented by the asterisk symbol), field code operators (which look for specific words in defined fields, such as the Author field in a periodical database ...
Less than 5% of users used advanced search features (e.g., boolean operators like AND, OR, and NOT). The top four most frequently used terms were (empty search), and, of, and sex. A study of the same Excite query logs revealed that 19% of the queries contained a geographic term (e.g., place names, zip codes, geographic features, etc.). [9]
Searches that use Boolean operators (for example, "encyclopedia" AND "online" NOT "Encarta") can dramatically increase the precision of a full text search. The AND operator says, in effect, "Do not retrieve any document unless it contains both of these terms." The NOT operator says, in effect, "Do not retrieve any document that contains this word."
After indexing, spiders use links to discover and index new content from other websites.Unlike the alphabetically searchable index of a printed book, search engines manage vast databases of pages, making alphabetical searches impractical. Instead, they rely on query language to assist users in finding information.
The (standard) Boolean model of information retrieval (BIR) [1] is a classical information retrieval (IR) model and, at the same time, the first and most-adopted one. [2] The BIR is based on Boolean logic and classical set theory in that both the documents to be searched and the user's query are conceived as sets of terms (a bag-of-words model ).