|
At the heart of any search endeavour, no matter what
kind of search tool you are using, there are three areas that can
affect your search result significantly:
-
Content of search engine
-
Search logic or algorithm
-
Presentation of search result
We discussed last week how content of search engines
can significantly affect your search result. This week, we look
at search logic.
When confronted with a search engine, most of us type
one or few words in search window and hope the search result shows
most relevant information.
Now, what can you do besides typing a few relevant
words into the search window ?
Well, actually a lot ! You can specify that words must
be in the title of a page, or that specifying words must be in an
URL, or in a special HTML tag or you can use logical operators between
words like AND, OR, and NOT....
Most search engines employ keyword-based search system,
that work on occurrence or non-occurrence of search word to identify
relevant documents in its database. Though a few search engines
have started using fuzzy logic based searches - still these are
in experimental basis.
While keyword based searches are extremely powerful
and ideally suited for database search - its major weakness is its
inability to understand word meaning. As a result, it searches mechanically
for words - leaving the problem of synonyms squarely on searcher's
shoulder.
To give an example - searching for 'garment' will not
get you documents dealing in 'apparel' or 'clothes' or 'T-Shirt'.
Worse, the search engine may even overlook the keyword 'garments'
- unless it has facility for truncation.
So, as searcher, it becomes your responsibility to
construct search expression in such a way that it gets maximum relevant
documents from search engine database.
Every search engine provides a set of tools for constructing
efficient search expression. Perhaps the most important of all is
the Boolean search operators.
What is Boolean Search ?
Boolean searching is based on a system of symbolic
logic developed by George Boole, a 19th century English mathematician.
Most keyword searchable computer databases support Boolean searches.
Boolean search techniques may be used to perform accurate searches
without producing many irrelevant documents.
When you perform a Boolean search, you search the computer
database for the keywords that best describe your topic. The power
of Boolean searching is based on combinations of keywords with connecting
terms called operators. The three basic operators are the terms
AND, OR, and NOT.
AND
This operator combines two search words in a search
expression that retrieves documents containing BOTH the words.
For example: The search expression 'Fabrics AND Buyer'
will retrieve all documents that have both the words 'fabrics' and
'buyer
AND operator narrows a search. More words you combine
with AND - greater will be precision in search result. However,
you may also miss out relevant documents that do not contain ANY
OF THE words specified.
OR
The OR operator combines two search words in a search
expression that retrieves documents containing ANY of the words.
For example, the search expression 'Agent OR Agents
OR Distributor OR Distributors' will fetch all documents that have
ANY of the search words.
Obviously, OR operator broadens or widens a search
to include documents containing any of the search words. This operator
is particularly useful when there are several common synonyms for
a concept or variant spellings of a word. However, indiscriminate
use of OR operator may fetch junk or unwanted documents.
NOT
NOT operator excludes unwanted documents having the
specified search word. For example, the search expression 'Buyer
NOT Agent' first fetches all documents that have the word Buyer
then goes on to remove all documents from this collection that have
the word 'agent' in it. The result is a collection of documents
that have the word buyer but not the word agent.
Boolean search terms may be combined in various ways
to carefully refine searches. For example:
(Buyer OR 'Buying Agent') AND (UK OR England OR Britain)
NOTE: A phrase (i.e more than one word) is always marked
with inverted comma (e.g. 'Buying Agent')
This place is too short for more explanation. Interested
readers may check following tutorials for graphical illustration
of Boolean operators.
Related Links:
Source: FAIDA
- Newsletter on Business Opportunties from India and Abroad
Vol: 3, Issue 12
July 11' 2002
Author :
Dr. Amit K. Chatterjee
(Amit worked in blue-chip Indian and MNCs for 15 years in various
capacities like Research and Information Analysis, Market Development,
MIS, R&D Information Systems etc. before starting his e-commerce
venture in 1997. The views expressed in this columns are of
his own. He may be reached at amit@infobanc.com
) |
|
