# fn:not - XPath XQuery Reference

Returns true if the effective boolean value of $arg is
               false, or false if it is true.deterministiccontext-independentfocus-independentThe value of $arg is first reduced to an effective boolean value by
            applying the fn:boolean() function. The function returns true
            if the effective boolean value is false, or false if the
            effective boolean value is true. fn:not(fn:true())false()fn:not(())true()fn:not("false")false()fn:not(1 to 10) raises a type error .