+----------+ +--------+
| Mannheim | ------+-> | Weimar |
+----------+ | +--------+
|
|
|
+----------+ |
| Potsdam | ------+
+----------+
+----------+ +--------+
| Mannheim | ------+-> | Weimar |
+----------+ | +--------+
|
|
|
+----------+ |
| Potsdam | ------+
+----------+