# and -- conjunction

## Description

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

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

• or -- disjunction
• not -- negation
• xor -- exclusive disjunction

## Ways to use symbol and :

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

## For the programmer

The object and is .

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

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

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