Boolean Searching

Boolean

Searching

What are Boolean operators?

The following terms are called Boolean operators:

“AND”

“OR”

“NOT”

Why do we call them “Boolean”?

• His theories formed the basis for using Boolean operators in Internet searches

• George Boole was an English mathematician who lived from 1815-1864

• He invented a branch of mathematics called Boolean algebra

How do you use Boolean operators?

Using AND:AND narrows a search

AND will bring back documents that use both the search terms you put in.

Example:

human AND rights

Using OR broadens a search

OR includes results that contain either of the words you type in.

OR is also a good tool to use when there are several common spellings or synonyms of a word.

Example:

impact OR effect

Using “OR”

NOT narrows a search

NOT includes results that contain one, but not the other, of the search terms you enter.

Examples:

dolphins NOT football

Java NOT coffee

Using “NOT”

Here’s another way to think about it:

Search results are shown in green Diagrams from http://tlt.its.psu.edu/suggestions/databases/search/booleansearch.html

“OR”

Search results are shown in green Diagrams from http://tlt.its.psu.edu/suggestions/databases/search/booleansearch.html

“NOT”

Diagrams from http://tlt.its.psu.edu/suggestions/databases/search/booleansearch.html

Search results are shown in green

Mini Quiz

Which will get you the MOST results:

A. AND

B. OR

C. NOT

Additional Search Techniques

Phrase searching:Use quotation marks (“ ”) around words that you want to

appear together in a specific order.

This is a great strategy for names and titles!

Example:

“Global warming”

“Bill Gates”

Additional Search Techniques

Truncation:Use an asterisk (*) to stand for any character or string

of characters.

This is a great strategy to use if you want to find multiple spellings or word endings.

Example:

Child* (searches for child, children, childhood, etc.)

Terror* (searches for terror, terrorist, terrorism)

How do search engines and databases

treat Boolean operators?

Not consistently (different syntax)•

May enter keywords by hand or via a pop-up box•

May have to go to an advanced search page•

The default operator may be “and” or “or”

Always check the help files to learn about searching in each system.

Google’s advanced search

Watch Google translate your search terms into its own syntax!

This is just like using the Boolean operator “NOT”

This is just like using the Boolean operator “OR”

This is just like using the Boolean operator “AND”

This is just like using “quotation marks” for a phrase search

Google Searching Tips

• Google is not case sensitive; enter either upper or lower case keywords.

• Google searches on every word you enter. Each additional word limits results.

• Punctuation is ignored.

• Google assumes an “AND” if you enter more than one keyword.

• You can use shortcuts in Google’s basic search box:

+ for AND - for NOT

Now you’re going to try it on your own!

Adapted from Bloustine, Jennifer. “Smarter Internet Searching.” S.O.S. for Information Literacy, n.d. Web. 25 Feb. 2010 and Shrock, Kathy. Effective Search Strategies. Kathy Schrock’s Guide for Educators. Discovery Education. n.d. Web. Retrieved 25 Feb 2010.