A celebrated result of Black (1984a) demonstrates the existence of a simple majority winner when preferences are single-peaked. The social choice follows the preferences of the median voter's most preferred outcome beats any alternative. However, this conclusion does not extend to elections in...

We present a new approach to the theory of imperfect competition and apply it to study price competition among differentiated products. The central result provides general conditions under which there exists a pure strategy price equilibrium for any number of firms producing any set of products....

While competition between firms producing substitutes is well understood, less is known about rivalry between complementors. We study the interaction between firms in markets with one-way essential complements. One good is essential to the use of the other but not vice versa, as arises with an...

Herbert Scarf has recently introduced an algorithm for integer programs based on the concept of primitive sets. We show that as the choice variables become continuous, this algorithm converges to a dual simplex algorithm. This result is robust in the sense that even before the limit is reached,...