A transversal generated by a system of distinct representatives (SDR) for a colection of sets consists of an element from each set (its representative) such that the representative uniquely identifies the set it belongs to. Theorem 1 gives a necessary and sufficient condition that an arbitrary...

A transversal generated by a system of distinct representatives (SDR) for a colection of sets consists of an element from each set (its representative) such that the representative uniquely identifies the set it belongs to. Theorem 1 gives a necessary and sufficient condition that an arbitrary...

A pre-recorded version of Leonid Hurwicz' Prize Lecture was presented on 8 December 2007 at Aula Magna, Stockholm University. The lecture was introduced by Professor Jorgen Weibull, Chairman of the Economics Prize Committee.