--- a/progs/app6.scala	Sun Oct 02 15:07:21 2016 +0100
+++ b/progs/app6.scala	Mon Oct 03 00:24:45 2016 +0100
@@ -22,6 +22,6 @@
 
 def ders(s: List[Char], r: Rexp) : Rexp = s match {
   case Nil => r
-  case c::s => ders(s, simp(der(c, r))) (*@\label{simpline}@*) 
+  case c::s => ders(s, simp(der(c, r)))             /*@\label{simpline}@*/ 
 }