Module Four - Boolean searching

I learnt Boolean searching over 20 years ago. It has been a long time since I have used it properly or in any depth.

Boolean searching
A precise method of searching online indexes and databases, the Library catalogue and the WWW using 'Boolean Operators' (the words 'and', 'or', 'not', 'with', 'near') to link search words and combine them in various ways to narrow or broaden a search as required.University of Melbourne, Library Basics

Simple, non boolean logic:

• one concept, can be expressed by a single term.
• I want to find some information on Alzheimer's disease.
  
• alzheimers
• I want some information on aluminum (American spelling only).
  
• aluminum

Simple boolean logic:

• more than one concept, but each term can be expressed by a single term.
• I want to find information on the role of aluminum (American spelling only) in Alzheimer's disease.
  
• aluminum AND alzheimers
• only one concept, but can be expressed by more than one term.
• I want to find information on aluminum (American spelling) OR aluminium (British spelling).
  
• aluminum OR aluminium
• I want to find information about Alzheimers disease, but I do NOT want anything which mentions aluminum.
• alzheimers NOT aluminum
  

Complex Boolean or nested logic

• more than one concept, and at least one concept can be expressed by more than one term.
• I want to find information on the role of aluminum (American and British spellings) in Alzheimer's disease.
• alzheimers AND (aluminum OR aluminium)
• The use of parenthses in boolean searching is the same as in the basic mathematics we learnt as primary students. Process what is in the brackets FIRST. This is required for proper processing of the boolean operators AND's and OR's. If the parenthses are left out many search engines read the query left to right. This would result in it finding pages with alzheimers and aluminum on the same page and all pages with aluminium.
  

Taken from: Colgate University Libraries.

• AND is used to narrow a search
• can be written as "AND" or "and"
• synonyms: &, +
  
• OR is used to broaden a search
• can be written as "OR" or "or"
• synonyms: |, ||, comma, ;
  
• NOT is used to narrow a search
• can be written as "NOT" or "not"
• synonyms: -
  
• "" double quotes turn search terms into exact phrases
• * an asterisk is a wildcard operator, it can replace one or more characters
• ? a question mark can replace a single character