canonical 'cases'/'induct' rules for n-tuples (n=3..7)
(really belongs to theory Product_Type, but doesn't work there yet)
By chapter:
chapters 1 and 2, maybe 3: Peter White
chapters 6, 7 and 8: David von Oheim
chapter 6, maybe 8: Gerwin Klein
chapters 3, maybe 4: Tanja Vos
chapters 1-3 at least: Stefano Bistarelli