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EXP101: AND, OR, NOT operators

Resources for debates, rhetoric, or contentious issues

Boolean Operators AND, OR, NOT = Logic

How do Boolean operators affect search results?

Venn Diagram with AND

 


AND makes a search smaller.

  • A search for rock AND roll will locate all records containing both the word "rock" and the word "roll", like music. It might also locate records that contain both words in a different context, such as "It recommends you roll the rock quickly."
 

 

Venn Diagram with OR

 

OR expands a search

  • A search for rock OR roll will locate all records containing either the word "rock" or the word "roll" -- not necessarily both. It will retrieve items about bakery rolls, tumbling, rocks, music, gemstones.
 

  

Venn Diagram with NOT

 

NOT excludes terms

  • A search for rock NOT roll will locate records containing the word "rock" but NOT the word "roll" . It will retrieve items about rocks, gemstones, diamonds, etc. Keep in mind that a search for "rock NOT roll" will return different records than the search "roll NOT rock."
 

 

Boole who? We credit him with the logic we use in our searches today. 

 George Boole (1815 - 1864) was a mathemetician from Lincolnshire, England . Boole was skilled in logic and his concepts have been used for applications of which he never dreamed, such as the basic design of digital computer circuits.  His symbolic reasoning, now called Boolean algebra, has been very influential in library database practices. Boole was self taught in mathematics.