We search for (Nash) implementable solutions on a class of one-to-one
matching problems which includes both the housing market (Shapley and
Scarf, Journal of Mathematical Economics, 1974, 1, 23-28) and marriage
problems (Gale and Shapley, American Mathematical Monthly, 1962, 69,
9-15). We show that the core correspondence is implementable. We show,
furthermore, that any solution that is Pareto efficient, individually
rational, and implementable is a supersolution of the core correspond
ence. That is, the core correspondence is the minimal solution that is
Pareto efficient, individually rational, and implementable. A corolla
ry of independent interest in the context of the housing market is tha
t the core correspondence is the only single-valued solution that is P
areto efficient, individually rational, and implementable.