# or -- disjunction

## Description

t or u -- returns true if t is true or u is true.

If t is true, then the code in u is not evaluated.

• and -- conjunction
• not -- negation
• xor -- exclusive disjunction

## Ways to use symbol or :

• "Expression or Expression" -- see Expression -- the class of all expressions
• "Expression or Holder" -- see Expression -- the class of all expressions
• "Expression or Thing" -- see Expression -- the class of all expressions
• "Holder or Expression" -- see Expression -- the class of all expressions
• "Holder or Holder" -- see Expression -- the class of all expressions
• "Thing or Expression" -- see Expression -- the class of all expressions

## For the programmer

The object or is .

This operator may be used as a binary operator in an expression like x or y. The user may install binary methods for handling such expressions with code such as

         X  or  Y := (x,y) -> ...

where X is the class of x and Y is the class of y.