Transcript Mariya_Badeva_2_SearchTechniques

Search Techniques
Boolean Logic and Keyword
Searching
• Catalogues, index, subject directories, lists, etc.
• Field searches, keyword and sections searches, etc.
• Full-text search
In text retrieval, full text search refers to a technique for searching a
computer-stored document or database. In a full text search, the
search engine examines all of the words in every stored document as it
tries to match search words supplied by the user.
• NB! The perfect one-stop-legal-research-shop/tool does not exist. Do
not bother looking for it. Rather focus on learning about the limitations
and advantages of each research option.
• Ambiguities of natural language make full-text
search less precise
• A free-text search is likely to retrieve many
documents which are irrelevant to the search
question
But
• These can be overcome by using advanced
search techniques to structure machineunderstandable queries
• Boolean logic and keyword searching
Keyword searching refers to a search type in which you enter terms
representing the concepts you wish to retrieve. Boolean
operators are not used.
Boolean logic refers to a search in which symbols are used to
represent Boolean logical operators. In this type of search on
the Internet, the absence of a symbol is also significant, as the
space between keywords defaults to either OR logic or AND
logic. Many popular search engines traditionally defaulted to OR
logic, but as a rule are moving away from the practice and
defaulting to AND.
Implied Boolean logic has become so common in Web searching
that it may be considered a de facto standard.
•
•
Boolean logic (named after Irish mathematician George Boole)
Logical operators:
OR
AND
NOT
e.g. I want info on college
Find synonyms: college, university,
campus
e.g. I am interested in the
relationship between poverty and
crime
e.g. I want info on cats but don’t
want to read anything about dogs
• I would like to find out about cases/articles
dealing with the right of parents of pupils to
be exempt from paying school fees.
Pupil, student
School, but not university and not technicon
Parent, or guardian
(pupil OR student) AND (school NOT university
NOT technicon) AND (parent or guardian) AND
fee?
I. Query: I need information about university.
Boolean logic: OR
Search: university college
Note: AND / OR
II. Query: I'm interested in dyslexia in adults.
Boolean logic: AND
Search: +dyslexia +adults
III. Query: I'm interested in radiation, but not nuclear radiation.
Boolean logic: NOT
Search: radiation -nuclear
IV. Query: I want to learn about cat behavior.
Boolean logic: OR, AND
Search: cats felines +behavior
Advanced Search Techniques
• Search for phrases within quotations e.g. “death penalty”
• Proximity operators (e.g. NEAR)
• Field searching
e.g. TITLE: slavery (http://www.altavista.com/)
DEFINE: slavery (http://www.google.co.za/)
Quick Tip!
Best Bet Search Syntax
Place the plus sign ( + ) in front of all words you wish to retrieve
+influenza +birds
Place a phrase within quotations
"freedom of the press"
Putting it all together:
+“crime rate" +“South Africa"
• Truncation – searching for words with the same root
(e.g. work! or work? (Sabinet), fetches work, worker,
workforce, workplace, etc.)
• Plurals – e.g. school+ will find school or schools
• Wildcards – to retrieve variant spellings - e.g. Sabinet
wom#n will return woman and women; LN wom?n will
return woman and women
• Proximity – type a character between search terms to
specify that records found contain both terms, in order
typed with no more than specified number of words
between them
e.g. online w3 system
• Might differ from database to database – check the help
files!
• Thank you