(maxima.info)Logical operators

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7.4 Logical operators
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 -- Operator: and

     The logical conjunction operator.  'and' is an n-ary infix
     operator; its operands are Boolean expressions, and its result is a
     Boolean value.

     'and' forces evaluation (like 'is') of one or more operands, and
     may force evaluation of all operands.

     Operands are evaluated in the order in which they appear.  'and'
     evaluates only as many of its operands as necessary to determine
     the result.  If any operand is 'false', the result is 'false' and
     no further operands are evaluated.

     The global flag 'prederror' governs the behavior of 'and' when an
     evaluated operand cannot be determined to be 'true' or 'false'.
     'and' prints an error message when 'prederror' is 'true'.
     Otherwise, operands which do not evaluate to 'true' or 'false' are
     accepted, and the result is a Boolean expression.

     'and' is not commutative: 'a and b' might not be equal to 'b and a'
     due to the treatment of indeterminate operands.

 -- Operator: not

     The logical negation operator.  'not' is a prefix operator; its
     operand is a Boolean expression, and its result is a Boolean value.

     'not' forces evaluation (like 'is') of its operand.

     The global flag 'prederror' governs the behavior of 'not' when its
     operand cannot be determined to be 'true' or 'false'.  'not' prints
     an error message when 'prederror' is 'true'.  Otherwise, operands
     which do not evaluate to 'true' or 'false' are accepted, and the
     result is a Boolean expression.

 -- Operator: or

     The logical disjunction operator.  'or' is an n-ary infix operator;
     its operands are Boolean expressions, and its result is a Boolean
     value.

     'or' forces evaluation (like 'is') of one or more operands, and may
     force evaluation of all operands.

     Operands are evaluated in the order in which they appear.  'or'
     evaluates only as many of its operands as necessary to determine
     the result.  If any operand is 'true', the result is 'true' and no
     further operands are evaluated.

     The global flag 'prederror' governs the behavior of 'or' when an
     evaluated operand cannot be determined to be 'true' or 'false'.
     'or' prints an error message when 'prederror' is 'true'.
     Otherwise, operands which do not evaluate to 'true' or 'false' are
     accepted, and the result is a Boolean expression.

     'or' is not commutative: 'a or b' might not be equal to 'b or a'
     due to the treatment of indeterminate operands.