Topics covered:
Selling leavened foods to a gentile before Passover. Giving food to a dog on Shabbos if the dog is likely to transfer that food from private to publc domain. On the eve of Shabbos: giving mail to a carrier, setting sail on a voyage, commencing a siege in war, giving white or dyed clothes to a launderer. Asking the the non-Jewish captain of a ship to stop the ship on Shabbos (which we don’t do, but the reason we consider this question is fascinating…).