Am Freitag, 25. Januar 2013 schrieb Alex Sassmannshausen:
> I guess a generation would only be destroyed at a junction, not when
> moving back and forth in straight lines.
> A ------> B ------> C
> You could travel from C back to A and back to C without having to
> re-install packages...

Yes, that is the idea. However, at a junction, all the past future would be 
lost: Once at A, if you install B', then you start an alternate future, and 
B and C would be deleted.

Andreas