2. Tools of search
Conditionally tools of search are subdivided into search means of a help
type (directories) and retrieval systems in the pure state (search
engines).
2.1 Thematic catalogues
The search tools of the first type name subject, or thematic catalogues
more often. The company owning such catalogue, continuously conducts huge
work, investigating, describing, cataloguing and displaying on half-glasses
contents of WWW-servers and other network resources scattered worldwide.
Result her(it) titanium of efforts is the constantly updated hierarchical
catalogue, at the top level the most general(common) categories, such as
“business” are assembled, "”science", "”art" etc., and the elements of the
lowermost level represent the links to separate WWW-pages and server
together with the brief description of their contents.
Guarantees that such catalogue really covers all contents WWW, nobody will
give, however possible(probable) not the completeness and selection of
materials is with interest expiated there, that for the present not under
force to any computer - intelligence of selection.
The subject catalogues give also opportunity of keyword search. However
search this occurs not in contents of WWW-servers, and in their brief
descriptions stored(kept) in the catalogue.
The subject catalogues Internet can be counted literally on fingers, as
their creation and support require(demand) huge expenses. To most known
concern Yahoo, WWW Virtual Library, Galaxy and some other.
Yahoo.
Is most popular in the population Internet the catalogue Yahoo. On the
first page Yahoo, located to the address http://www.yahoo.com, you receive
access to two basic method of work with the catalogue - keyword search and
hierarchical tree of sections.
Having begun descent(release) on sections of the catalogue, you will see,
that each section contains the precisely same field for input of keywords
and button Search, starting search.
Each section can include as transfer included in him(it) and actually links
to pages concerning at once all section, with their brief descriptions.
Instead of travel you can at once get in the necessary place of the
catalogue Yahoo with the help of search. Having entered one or several
keywords divided(shared) by blanks, in a line of search and having pressed
the button Search, you receive the list all in Yahoo, that comprises the
specified keywords. This list will be divided(shared) into two parts -
“categories” and “sites”.
If total of the links returned as a result of search, exceeds 25, the list
of the links will be broken on some parts.
Magellan.
But not seldom happens so, that the list, given out by the machine, is very
great and to see (overlook) it(him) simply not really. An output(exit) from
this situation can become stricter selection of the information brought in
the catalogue. One of most known such systems - catalogue Magellan to the
address: http: // www.mckinley.com
This database contains the items of information on 80 thousand WWW-pages -
that very much not much in comparison with those in millions, which exist
in a network. However if Yahoo as the description of a resource uses one -
two lines of the text, the employees of system Magellan on some of pages
brought in their database, write the small reviews, and also estimate
quality of these information resources on a five-mark scale. Till past
bases of the reviews, Magellan owns as an own automatic index, for search
in which it is necessary to throw the switch under a field of input in a
rule(situation) entire database.
As a rule search represents one or several keywords divided(shared) by
blanks.
Point.
The service, similar by the principles, of firm Point (http: //
www.pointcom.com) in general basic emphasis does(makes) not on search, and
on work with the thematic catalogue.
The service Point is known in a network for that its(her) employees are
constantly engaged оцениванием of network resources and conduct the lists
of those sites, which they consider(count) belong to “ to the best five
percents(interests) WWW ”.
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.
Results of search Alta Vista, as well as Yahoo, gives out as the list of
the links on the documents, but instead of the description of each document
near to his(its) heading you will see simply first some lines of his(its)
text. If will be found more than 10 documents, Alta Vista will break their
list on pages till 10 links on everyone. Alta Vista sorts the links so that
on the first place there were “most important” documents with your keywords
at definition of a degree of importance taking into account the following
factors:
Whether the keywords into heading of the documents enter;
Whether these words in the first several lines of the documents contain;
As far as are close to each other in the text the keywords are found out.
Info seek
Info seek, entered in of operation at the end of 19996 years, is somewhat
reminiscent Alta Vista, however volume of the complete texts, surveyed by
him,(it,) of the documents yet does not exceed 30 million. Web-pages. The
address: http://www.infoseek.com. It is rather powerful system having high
speed and idle time in circulation. Opportunities of drawing up of search
almost same, as well as in Alta Vista, but not so rich. At almost complete
preservation of values of marks "«plus", "«minus" and "«inverted commas",
sensitivity to a difference header both lower case letters and opportunity
to limit search to fragments Web- of pages, Info seek yet has no ability to
define(determine) beside the worth terms (there is no operator NEAR), to
limit search by date of updating a source and, main, to truncate
terminations(ending) the key terms.
But the given retrieval system contains weight of facultative functions.,
for example, opportunity concerns to those to define(determine)
quantity(amount) of the links in WWW on concrete page, that is to judge, as
far as she(it) is popular or, on the contrary, to find out, how many links
to external pages contain on the given site, more correctly, how many from
them are reflected in index files Ultra seek. Use of special function Image
seek allows to find in Internet of the image (figures, photo) on the
certain subject. Info seek has also one of the best directories of
resources of a Network.
HotBot
By one of powerful search means in World Wide Web can attribute (relate)
HotBot, containing the items of information on the complete texts 110
million. Pages. The address: http://www.hotbot.com. HotBot belongs to the
newest systems, therefore his (its) profound search gives amazingly ample
opportunities for detailed elaboration of search. It is reached (achieved)
at the expense of use of the multistage menu offering various variants of
drawing up of the search instruction. It is possible to carry out search on
presence in the document one or several terms, search on a separate phase,
search of the concrete person or links to the certain electronic address.
For the greater detailed elaboration of search probably application of
conditions SHOULD (can contain), MUST (should necessarily contain), MUST
NOT (should not contain) in relation to any concepts. Besides HotBot
represents возможность ограничить search by date of creation or last
updating of the document, on geographic a rule(situation) of the server.
Top of service opportunities is the search of the documents containing
certain types of files, for example video. For this purpose it is necessary
only to make a mark in special item of the menu of search.
WebCrawler.
It is one more tool of search such as search-bot (search the robot).
The address: http: // www.webcrawler.com. The search here is very simple.
Enter maximal keywords into a field of search, press Search.
Lycos.
It is the large database that contents of all pages, found by Web.
The address: http://www.lycos.com.
World Wide Web Worm.
You will find this tool of search on
http://www.cs.colorado.edu/home/mcbryan/wwww.html. It is one more extensive
index of sites Web.
In each concrete case it is expedient to use the tool of search. You should
try to carry out(spend) search through one tool and, if you have not
received results, to pass to another. But nevertheless what tool to use?
First of all it is better to take advantage of the thematic catalogue such
as Yahoo, size at them rather small, but the speed is great. If to find the
necessary information it was not possible, it speaks that you are
interested in a too narrow subject, or badly correspond with your subject
the keywords, chosen by you. It does not mean, that the necessary
information in WWW is not present - it will be simple to find her(it) more
difficultly. For its(her) search to you will be reached to take advantage
of more primitive, more automatic and consequently by more universal
systems such as Alta Vista.
2.3. Russian retrieval systems
The retrieval systems of global scale concentrate the basic attention on
English resources of a Network. The task of search of the information on
servers within the limits of the separate countries is carried out with
systems of local character specially adapted for features of concrete
languages. There are similar search means and in Russia. All of them are
united by (with) an opportunity of processing of materials in all Cyrillic
codes*. However on capacity and level of offered service the Russian
retrieval systems considerably differ from each other.
Rambler, "Апорт" and "Яndex" now concern to leading group systems.
Rambler
Among favorites is allocated Rambler (http://www.rambler.ru), becoming with
the first professional domestic retrieval system. This system provides full
text search on 3 million. Pages located on more than 15 thousand Web sites
of Russia and the countries of near foreign countries. Besides Web-servers,
the week archive of news of hierarchy relcom is surveyed also.
Rambler has close to an optimum conclusion of results of search. Even in a
normal form the link on found object inserts the complete information. The
system is designed in such a manner that the same document in the various
coding is shown in the various coding are shown only once, and his(its)
concrete addresses are summarized in the list. it’s a reduces time on
analyze of the received results because of absence of duplication of the
same documents.
The main lack Rambler consists in impossibility to carry out search on the
whole phase or even to specify in searches limiting distance of the
required terms from each other. The casual combination of completely untied
words results in distribution of the links on the documents, are absolutely
not relevant to search.
Апорт
The retrieval system Апорт (http://www.апорт.ru) is supplied with weight of
various functions carrying her(it) number user-friendliest.
One consists of the main advantages Апорт in ample opportunities of drawing
up of search. Besides the traditional operators "both" and “or”, search on
the whole phase, the system is capable to isolate combinations of the terms
located in the text by a number (line) with each other. Апорт offers an
opportunity of machine translation of search with Russian on the English
language and on the contrary. Both Rambler, and Апорт are capable to
allocate the same document in the various coding and to give out the link
to him (it) only of time, listing(transferring) concrete addresses in the
list URL. Unfortunately, thus the items of information on the out-of-date
versions of the same page in time do not leave which are listed
(transferred) as existing, having a difference only in date of updating.
One more lack of this system is not always correct processing of the names
of pages, because of what as a result of search the document without the
name » frequently is underlined «.
Яndex
Retrieval system Яndex (http://www.yandex.ru), where besides servers of
domains «ru< and «su< Яndex индексирует the contents of foreign Russian Web-
sites.
The main distinctive feature of this system is the deep morphological
analysis of the process able terms. The most powerful linguistics allows to
take into account practically all possible (probable) shades of the use of
keywords and to make search maximum precisely. Яndex has the good mechanism
of recognition of one document in the several coding or on mirror servers.
After leading Russian тройкой there are some more search means, among which
“ the Russian machine of search ” (http://search.interrussia.com), "«TELA-
search" (http://tela.dux.ru/) and Russian Internet Search
(http://www.search.ru). While all these servers do not differ neither
breadth of search, nor by comfort, and can be used only as addition to
conducting search means.
The search service in the Russian block Internet, as well as all over the
world, develops promptly. There is no doubt, that in the near future
parameters of existing systems will be raised, the new generations of
search means giving to the users still (even) the large opportunities will
appear.
