But it's wrong. I'll assume the times you gave were in the UK's timezone. Here they are rewritten to use Germany's timezone. a + 1:00 = a 16:00 + 14:0

But it's wrong. I'll assume the times you gave were in the UK's timezone. Here they are rewritten to use Germany's timezone. a + 1:00 = a 16:00 + 14:00 = 03:00 13:00 + 13:00 = 01:00 Still think this makes sense? Time deltas? Then you don't have the timezone or epoch problem. Works fine. But time stamps? You can't add two time stamps and get a sensible answer. Time stamps form a torsor, not a group: http://math.ucr.edu/home/baez/torsors.html http://math.ucr.edu/home/baez/torsors.html