  In open quantum systems, entanglement can vanish faster than coherence. This
phenomenon is usually called sudden death of entanglement. In [M. O. Terra
Cunha, New J. Phys. 9, 237 (2007)] a geometrical explanation was offered and a
classification of all possible scenarios was given. Some classes were
exemplified, but it was still an open question whether there were examples for
the other ones. This was solved in [R.C. Drumond and M.O. Terra Cunha,
arXiv:0809.4445v1]. Here we briefly review the problem, state our results in a
precise way, discuss the generality of the approach, and add some speculative
desirable generalizations.
