CONTRIBUTORS

--- a/CONTRIBUTORS	Mon Jul 27 22:08:46 2015 +0200
+++ b/CONTRIBUTORS	Mon Jul 27 22:44:02 2015 +0200
@@ -18,6 +18,9 @@
   (semi)domains like units, associated elements and normalization
   wrt. units.
 
+* Summer 2015: Florian Haftmann, TUM
+  Fundamentals of abstract type class for factorial rings.
+
 
 Contributions to Isabelle2015
 -----------------------------