Another proof that assignment games have singleton cores only if multiple optimal matchings exist

Complementary slackness of a pair of dual linear programming problems implies the remark of Sotomayor (2003) that assignment games have singleton cores only when multiple optimal matchings exist.The author thanks Marilda Sotomayor, William Thomson, and an anonymous referee for their helpful comments. This paper was finished when the author was visiting University of Rochester. JEL Classification Numbers: C71, C78, D58