Presentation on theme: "What are Boolean Operators? Mrs. Mersand December 2007."— Presentation transcript:
What are Boolean Operators? Mrs. Mersand December 2007
Boolean operators are named after George Boole, an Englishman, who invented them as part of a system of logic in the mid-1800's. The most common Boolean operators are AND, OR, NOT and NEAR, additionally, () can be used They are used to combine search terms when doing research In math, they are used to connect logical statements
No… they arent leaning ghosts….
And Would everybody wearing Jeans, please stand up # _____ Would everybody wearing Sneakers please stand up # _____ Would everybody wearing jeans and sneakers please stand up # _____
Venn Diagram of AND Jeans Sneakers
AND Explained Using the operator AND between keywords will limit the results of a search because all the keywords have to be present in order for an item to be retrieved.
OR Would everybody wearing jeans please stand up#______ Would everybody wearing sneakers please stand up#______ Would everybody wearing jeans OR sneakers please stand up#______
Venn Diagram of OR Jeans Sneakers
OR Explained Using the OR operator results in either or both of your search terms appearing in your results. Using the OR operator will result in a larger number of retrieved items and therefore expands the search.
NOT The NOT (or AND NOT) operator forbids the word after it from appearing in the items resulting from your search. Would everybody wearing Jeans but NOT sneakers, please stand up
Venn Diagram for NOT Jeans Sneakers
NOT Explained Not helps to limit your search because it takes out a category of undesirable results. NOT or AND NOT thus narrows or limits a search by excluding the keyword immediately following it.
NEAR Finds the terms within 10 words of each other Domestic NEAR Violence would make sure these two words appeared close enough to each other that they would be referring to domestic violence
( ) Used to group together words or phrases, for example (domestic NEAR violence) and (police AND trial) Brings could be used to search for domestic violence that has been interrupted by the police or gone to trial
Order of operators Just as in math, certain operators are done first. The order for Boolean operators is: ( ) NEAR NOT AND OR
Be sure to use proper search structure What would the following search bring up? Dogs AND ((rabies OR rabid) NOT (domestic OR Pet) ) The search will look for the words rabies and rabid Then domestic and pet Then remove all results that contain the words domestic or pet from the results Then remove anything that does not contain the word dog from the results
Now lets try some on our own You should always use more than one search engine when you are doing research Try thinking out of the box, give Google a break!! Other options infomine.ucr.edu www.lii.org www.ipl.org www.nettrekker.com www.altavista.com www.mama.com www.dogpile.com www.yahoo.com www.surfwax.com www.ixquick.com