[en] The author has explained how the naive obstructions to unifying vacua with different net generation numbers can be overcome, and she gave a class of examples of chirality-changing phase transitions in four dimensions. The phenomenon exhibited here presumably occurs quite generally; it would be very interesting to understand whether in fact one can connect all vacua with N ≤ 1 supersymmetry at low energies. For this an F-theory analysis could be quite instructive, once that approach is developed more fully for four-folds. Perhaps the next in principle question to ask along these lines is whether there could be any physical process which changes the number of supersymmetries