expression evaluates to true or true true true or false true false or true true false or false false the not operator unlike and and orthe not operator operates on only one boolean value (or expressionthis makes it unary operator the not operator simply evaluates to the opposite boolean value not true false not not not not true true much like using double negatives in speech and writingyou can nest not operators though there' never not no reason to do this in real programs table - shows the truth table for not table - the not operator' truth table expression evaluates to not true false not false true mixing boolean and comparison operators since the comparison operators evaluate to boolean valuesyou can use them in expressions with the boolean operators recall that the andorand not operators are called boolean operators because they always operate on the boolean values true and false while expressions like aren' boolean valuesthey are expressions that evaluate down to boolean values try entering some boolean expressions that use comparison operators into the interactive shell ( and ( true ( and ( false ( = or ( = true the computer will evaluate the left expression firstand then it will evaluate the right expression when it knows the boolean value for each