Trading by basket
Q: ??? Consider a country in which people live in high buildings and
buy things from street vendors, using some form of money. Each building
is equipped with a pulley in the eaves over which runs a long rope with
a basket on it, operable by either party. Is there a system by which a
resident and a vendor who don't trust each other can conduct trade?
Note that either party may plan to play the opposite role with someone
else later.
rec.puzzles, 11 Apr 1996