> To make this set really useful > there must be a function (less :: "Real" -> "Real" -> Bool), > which always terminates and checks absolutely sure, if the > first argument is less than the second. It will be useful enough if one of the numbers is a constant. Otherwise you could check for equality of "a" and "b" by (not (less a b) && not (less b a)). That was not what I wanted to say. ------------------------------------------------------------------------------- Christoph Herrmann E-mail: [EMAIL PROTECTED] WWW: http://brahms.fmi.uni-passau.de/cl/staff/herrmann.html