Internet

Internet

Firm Point Conducts a shared database all “ of five-percentage WWW-pages, where about everyone it is possible to read the detailed license.

Virtual Library.

The most old subject catalogue WWW is the catalogue Virtual Library:

http: // www.w3.org/hypertext/DataSources/bySubj ect/Overview.html

This system full enough covers a scientific layer WWW - servers of universities, laboratories and educational institutions.

Russia-On-Line Subject Guide.

For the users in our country the certain interest can represent the thematic catalogue Russia-On-Line Subject Guide, located to the address http://www.online.ru/rmain. This catalogue contains rather motley assembly of the links on foreign sources plus the thematic review of the Russian and Russian resources WWW.

2.2. Automatic indexes.

It is possible to approach to a problem of search of the information in Internet and on the other hand. There are programs in which have loaded some thousand well-known URL-addresses. Being is started on the computer with access to WWW, this program begins automatically to download from a network the documents on it URL, and from each new document she(it) takes all links, contained in it,(him,) and adds them in the base of addresses. As at the end all WWW the documents are connected among themselves, early or late such program will bypass all Internet.

Certainly, the program can not understand as or classify that she(it) sees in a network. The programs of such type refer to as robots. They are limited to the tax of the statistical information and construction indexes in the texts of the documents. The database, collected by the robot, - index - stores (keeps) in it, simply speaking, item of information on that in what WWW-documents to contain those or other words.

Such the automatically collected index also underlies retrieval systems of the second sort, which frequently and name - automatic indexes.

The automatic index consists of three parts: the program - robot collected by this robot of a database and the interface for search in this base, with which the user works. All these components quite can function without intervention of the man.

As any classification of materials in such systems are absent, it is necessary to resort to them only then, when you precisely know keywords concerning that it is necessary, - we shall tell, a surname of the man or it is enough some of rare terms from the appropriate area. If to set search on the a little widespread words, you will have not enough life to bypass all URL-addresses, received as a result of search, - for example, the index of system Alta Vista contains of 11 billions words taken from 30 millions of WWW-pages.

An automatic index of WWW-pages exists much: WebCrawler, Lycos, Excite, Inktomi, Open Text and others. Some of them (for example, Lycos) represent more or less successful synthesis of the subject catalogue and automatic index.

Alta Vista.

Its(her) address http://altavista.digital.com. This system has appeared in December 1995. She (it) one of largest on volume of indexes from all such retrieval systems both most powerful and floppy rules of construction of searches. Alta Vista understands two different languages of searches rather strongly distinguished from each other. On the first page Alta Vista you see the form for simple search (Simple Search), and the panel of heading at the top of page contains the button Advanced Search, having pressed which, you receive the form for complication of search.

Except for WWW-pages, Alta Vista conducts a separate index for clauses from more than 14000 conferences Usenet (including hierarchy of groups relcom. *).

Search Alta Vista: that Alta Vista worked on group of words, only when they cost(stand) beside, it is necessary to conclude this group in inverted commas. If it is necessary to exclude from result all documents containing a certain word, it is necessary to attribute this word with is familiar “minus”.

The word without any mark works in search precisely the same as also it with is familiar “plus”.

As against Yahoo, by default Alta Vista searches of entry of the whole words. The ordered terms should stand in the document separately, instead of to be a part of other chains of symbols. If you need to find of all entry of a word, even when it is included into structure of other words, use a symbol *. The asterisk can stand only at the end of a word, and prevent giving many (too much) of results, Alta Vista requires(demands), that the word which is coming to an end on *, should consist not less than of 3 letters. Moreover, a symbol * allows to find not any termination (ending) of a word, but only not exceeding length of five symbols and not containing of capital letters or figures.