PageRank is
defined as follows: We assume page A has pages T1...Tn which point to it (i.e.,
are citations). The parameter d is a damping factor which can be set between 0
and 1. We usually set d to 0.85. There are more details about d in the next section.
Also C(A) is defined as the number of links going out of page A. The PageRank
of a page A is given as follows: PR(A)
= (1-d) + d (PR(T1)/C(T1) + ... + PR(Tn)/C(TN))
- Sergey Brin, Lawrence Page;
The Anatomy
of a Large-Scale Hypertextual Web Search Engine; 1998. |
Google is
one of the smartest search engines. Google was originally created by Stanford
University
students Sergey
Brin and Larry Page, and retains a well thought out structure and methodology.
The site actually runs on thousands of linked PC's distributed in centres located
in different places around
the
world,
and
usually
provides
relevant results with very fast response times.
Google uses a page ranking system
to determine
which
sites are returned at the top in response
to a search query. In Google's words:
In essence, Google interprets a link from page A to page B as a vote,
by page A, for page B. But, Google looks at more than the sheer volume of votes,
or links a page receives; it also analyzes the page that casts the vote.
This method ensures that the pages most highly recommended by other pages are
returned closest to the top of a search listing. This technique is really a kind
of centralized analysis of peer-to-peer data, and works quite well.
The Google advanced
search page provides a menu driven way to search the Internet,
and text equivalents
of these features are listed below:
Search
Features |
Function
| Query Example
| Results
|
Boolean
| +space
+mars -venus |
"space" and "mars" but not "venus" |
|
space OR mars
| "space"
or "mars" Note the OR must be capitalized. |
|
space and (mars OR venus)
| "space"
and either "mars" or "venus" Always put brackets around OR clauses connected
to an AND. |
Phrases
| +electric
+"fastest car" | includes
phrase "fastest car" |
Fields
| allinurl:garden
rose | "garden"
and "rose" in the URL |
| gardens filetype:pdf | Searches only PDF format files. |
|
inurl:garden |
"garden" in
the URL |
| link:LivingInternet.info | pages
that link to "LivingInternet.info" |
| related:LivingInternet.info | pages
that are related to "LivingInternet.info" |
|
site:garden |
"garden" in
the site domain name |
Other Google search options are described below.
- Languages.
You can set your page display preferences to a wide range of languages,
and search in
international language sets
- SafeSearch. Provides a
safe search option where most adult content pages are filtered out and
not returned
in search results
- Wildcards. Google doesn't support
wildcards, so for example instead of searching for "comed*" you need to search for
"+comedy +comedian".
Resources. Additional Google related resources are listed below: