Subject: Search engines. Search for information or information object in the text, file structures, databases, the Internet. Use of keywords, phrases to search for information. Search term combinations.
Purpose: To study ways to search for information in text, in file structures, in databases, on the Internet.
Learning aids: PC, Internet.
Explanations for the execution of the work:
The search for information is a task that mankind has been solving for many centuries. As the volume of information resources potentially available to one person grew, more and more sophisticated and sophisticated search tools and techniques were developed to find the necessary document. Extensive opportunities for working with large amounts of information are provided by Interner search services.
If there is primary information on the search topic, documents can be searched for by search engines. In this case, one should distinguish between simple, advanced, contextual and special search techniques.
Simple search refers to searching Web resources for one or more keywords. The disadvantage of a simple search is that it usually returns too many documents, among which it is difficult to choose the most relevant ones.
When using advanced search, keywords are linked by logical relation operators. Advanced search is used when simple search methods give too many results. With the help of logical relationships, the search task is formed in such a way as to more accurately detail the task and limit the selection area, for example, by publication date or data type.
Contextual search is a search for an exact phrase. It is convenient for abstract information retrieval, but is not available in all search engines. First of all, in order to provide such a possibility, the system must work not only with indexed files, but also with full-fledged images of Web pages. This operation is quite slow, and not all search engines perform it.
Special search is used when searching for Web pages containing links to specified URLs, containing specified data in service fields, for example, in the title field, etc.
Advanced Search. In addition to the simple search facility, search services typically provide advanced search facilities. These tools allow you to more accurately formulate the search task, but require some experience and work noticeably slower. In most search engines, advanced search commands are formed using logical commands. The convenience of using logical commands, in particular, is due to the fact that many search engines implement simple search commands in different ways. Each system strives to make simple search tools the most convenient, and advanced search tools the most standard. However, different search engines use different notations to denote logical operators. Therefore, it is desirable to learn the syntax of the search queries of the selected search engine before performing an advanced search.
Let us consider in more detail the operators of logical relations (logical commands).
The logical operator OR (OR) is used to form a search query if the search text must contain at least one of the terms connected by this operator. This operator in various search engines can be designated in one of the following ways: | ; OR; OR.
For example, the result of the query “Black OR sea” – will be represented by a list of links to documents that contain the word “Black”, or the word “sea”, or both of these words together.
In some search engines, as noted above, keywords in a query are linked by this logical relationship by default.
Using the logical operator AND (AND) searches for documents containing all the terms connected by this operator. This operator can be denoted in one of the following ways: +; AND; &; AND.
For example, the query – “Black AND sea” – will find documents that contain the words “black” and “sea”.
The logical operator NOT (HE) allows you to search for documents in the text of which there are no terms following the given operator. This operator can be denoted in one of the following ways: not; !; ~; NOT.
For example, for the query – “Black NOT sea”, the result is documents in which there is the word “Black” and there is no word “sea”.
With the help of logical operations, you can create quite complex queries. A multi-word query interspersed with operators will be interpreted according to their precedence. The AND and NOT operators traditionally have higher precedence, so a multi-word query is first grouped by the AND and NOT operators, and only then by the OR operators. For example, the query “Black AND sea OR Crimea” will find documents that either necessarily contain the words: “Black” and “sea”, or the word “Crimea”, or all three words.
You can change the grouping order using parentheses. The statement in parentheses will be executed first. Using parentheses allows you to build nested queries and pass them as arguments to operators. Thus, the query “Black AND (sea OR Crimea)” will find documents that necessarily contain the word “Black” and one of the two words “sea” or “Crimea”.
Using nested queries, you can significantly limit the scope of the selection, freeing the resulting list from unnecessary references. So, for example, if we are interested in information about a vacation in the south at sea, but only on the Russian coast, then we can try to use something like this query – “rest AND ((Azov OR Black) AND sea) NOT (Crimea OR Turkey OR Bulgaria)” .
The use of parentheses to control the order in which a search job is executed is allowed by most major search engines.
Advanced search yandex.ru
|“||Detects exact quoted words or phrases|
||||Find any of the words. It is enough to put the symbol | between the words, and you will get pages that contain at least one of the query words.|
|~||Excludes pages that contain a word or phrase.|
|()||You can build arbitrarily complex constructions by substituting entire expressions in each of the operators instead of a single word. In order for Yandex to understand you correctly, enclose expressions in parentheses.|
|&||Limit search to pages where query words are within a sentence|
|&&||If you need documents where the given words are present – no matter at what distance and in what order – connect them with an operator|
|!||Capitalized and lowercase words are considered different forms of the same word, so it doesn’t matter which case to use in the query. The exception is the exact form operator. This is useful if the proper name you are looking for matches a common phrase, such as the group !Black coffee. All words that you provide in the query are searched by default taking into account morphology. To turn it off, use the ! before the word (no space).|
|/||You can specify the maximum allowed distance between any two query words by placing a / character after the first word, followed immediately by a number indicating the distance.|
|*||Replacement of part of a word. Journalist*|
|?||Replacing any character. Journalist?|