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Internet Research – Illustrated,
Fourth Edition
Unit B
Internet Research: Unit B
Constructing
Complex
Searches
Internet Research – Illustrated, Fourth
Edition
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Objectives
Understand Boolean operators
Narrow a search with the AND operator
Expand a search with the OR operator
Restrict a search with the AND NOT
operator
Internet Research – Illustrated, Fourth
Edition
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Objectives (cont)
Use multiple Boolean operators
Search with filters
Combine Boolean operators & filters
Use metasearch engines
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Constructing Complex Searches
Complex searches
~ searches using Boolean operators to
expand, narrow, and restrict search results
~ also called advanced searches
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Understanding Boolean Operators
Boolean operators are special words or
symbols used to connect keywords and
phrases in a search
Boolean operators:
▪ AND / +
▪ OR
▪ AND NOT / -
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TERMS TO USE
Boolean operators
~ words & symbols that connect
keywords & phrases to tell search tools
how to interpret a search
Default operator
~ the Boolean operator used
automatically by a search tool
(most search tools use AND)
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CLUES TO USE
Always use all
CAPITAL LETTERS
for Boolean operators
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Understanding Boolean Operators
~ define the relationships between keywords
and phrases and help focus search results
~ either narrow or broaden a search, thereby
decreasing or increasing the number of
results
~ are based on Boolean logic, a
mathematical syntax, in which keywords act
as nouns and the operators act as
conjunctions, joining keywords in a way that
search tools can interpret
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Venn Diagrams
Venn diagrams
~ are used to illustrate Boolean logic
and searches using Boolean operators
~ were created by John Venn to explain
visually what George Boole, creator of
Boolean Algebra, had described
symbolically: the intersection, union,
and exclusion of sets
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Venn Diagrams
Each circle represents a set or Web pages returned
by one concept in a search.
When circles overlap it indicates some pages are
returned for both concepts. The area of overlap is the
intersection of the sets.
When a search returns all of the pages in both circles,
it is the union of the sets.
When a set is left out of results, it is an exclusion of
the set.
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Venn Diagrams
Using Venn diagrams to represent
Boolean searching:
This represents the results for a
search.
Every Web page that contains
the search terms is in this set.
one set
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Venn Diagrams
Using Venn diagrams to represent
Boolean searching:
This represents a search
using AND to limit the
results.
intersection
of two sets
Every Web page that
contains both search terms
is in the highlighted
intersection of the two
sets.
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Venn Diagrams
Using Venn diagrams to represent
Boolean searching:
This represents a search
using OR to expand the
results.
union
of two sets
Every Web page that
contains either search term
is in the highlighted union
of the two sets.
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Venn Diagrams
Using Venn diagrams to represent
Boolean searching:
This represents a search using AND NOT
to limit the results.
Every Web page that contains the search
term in the white set is excluded from the
results, which are highlighted in green.
exclusion
of a set
Only pages containing the first search
term (in green), but not containing the
second search term (in white), are
included in results.
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CLUES TO USE
When uncertain about which
Boolean operator to use in a search,
sketch a quick Venn diagram and
label it with your search terms and
it will become clear.
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TERMS TO USE
Syntax
~
rules in a language, like grammar,
that standardize usage
Venn diagrams
~ drawings used to represent
Boolean logic and searches using
Boolean operators
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Narrowing the Search with
the AND Operator
The AND operator
~ AND narrows or limits your
search, thereby decreasing the
number of search results
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Narrowing the Search with
the AND Operator
Use AND to:
▪ focus or narrow your results
▪ force the search of a stop word
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Narrowing the Search with
the AND Operator
An intersection of two sets occurs when you use AND:
apples
plums
Web pages
containing apples
Web pages
containing plums
Web pages containing both apples and plums.
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CLUES TO USE
Most search engines accept +
instead of AND
Some search engines require using +
instead of AND
Always leave a space in front of +
Never leave a space after +
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Expanding the Search with
the OR Operator
The OR operator
~ OR expands or broadens
your search, thereby increasing
the number of search results
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Expanding the Search with
the OR Operator
Use OR to:
▪ to broaden or expand your results
▪ to combine synonyms and related
words
▪ to have two spellings of a word
returned (for example: draught or
draft)
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Expanding the Search with
the OR Operator
A union of two sets occurs when you use OR:
apples
plums
Web pages containing either apples or plums.
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Restricting Queries with
the AND NOT Operator
The AND NOT Operator
~ AND NOT limits or narrows your
search by excluding or restricting
a concept from your results,
thereby decreasing the number of
results
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Restricting Queries with
the AND NOT Operator
Use AND NOT when:
▪ finding too many irrelevant results
▪ excluding a concept from your results
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Restricting Queries with
the AND NOT Operator
Using AND NOT excludes a concept:
apples
Web pages
containing
apples
but not plums.
plums
Web pages where the sets intersect are
excluded, even though they contain
apples, because the results must exclude
any page containing plums.
So, you are left with pages that contain
apples without containing plums.
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CLUES TO USE
Most search engines accept instead of AND NOT
Some search engines require using instead of AND NOT
Always leave a space in front of Never leave a space after -
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Using Multiple Boolean Operators
Using multiple Boolean operators
~ provides more focused, relevant results
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CLUES TO USE
When using multiple Boolean operators,
use parentheses ( ) to separate concepts
and to force the order in which your
search is performed.
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TERMS TO USE
Forcing the order of operation
~ using parentheses in a complex
query to force the search tool to
perform the part of the search inside
the parentheses
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Searching with filters
Searching with filters
~ narrows your search by telling
search tools to screen out
specified types of Web pages
~ returns fewer results that are
more relevant
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Searching with filters
Language filter
~ limits search to language you choose
File format filter
~ limits search to file format you choose
Date filter
~ limits search to pages first seen (or
sometimes last updated) within a specified
time period
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Searching with filters
Location filter
~ limits search to pages containing your
keywords in the location you choose
Domain filter
~ limits search to a specified domain
Censoring filter
~ limits search by attempting to filter
potentially offensive pages
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Combining
Boolean Operators and Filters
Use both Boolean operators & filters
~ when you need to perform
very specific searches
to return the most relevant results
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Using Metasearch Engines
Use metasearch engines
~ when you need to see
the most highly ranked results
from multiple search engines
~ to identify which search engine
might be best for a specific search
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Using Metasearch Engines
Metasearch engines:
–
–
–
–
–
–
dogpile
Fazzle
ixquick
metaCrawler
Search.com
Vivisimo
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CLUES TO USE
Since metasearch engine results can
be inconsistent, verify an engine you
want searched was actually used for
your search
If you don’t know that the metasearch
engine you are using can translate
your query effectively, use simple
searches
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Constructing complex searches includes:
understanding Boolean operators
using AND to narrow a search
using OR to expand a search
using AND NOT to restrict a search
understanding filters
using filters with Boolean operators
using metasearch engines
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Edition
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INTERNET RESEARCH
End