The simple circular model of horizontal product differentiation, where firms compete in price, implies an excessive entry of firms in equilibrium. When non-monotonic network effects are present, this result no longer holds. If consumers differ in their optimal number of other consumers choosing the same good, entry in equilibrium can be insufficient.

Economies throughout both the developed and developing world are interconnected like never before, whether it is the financing of global challenges, monetary integration among a group of countries or trade across national borders. This increasing degree of interconnection brings both opportunities and challenges for the countries involved. This volume provides an analysis of three distinct but closely related themes of economic interconnection: Public Finance, Monetary Policy and Market Issues. The collection will stimulate further debate on these issues and in doing so will help to broaden the exchange of ideas among economists in both academia and business.

This paper provides a thorough analysis of oligopolistic markets with positive demand-side network externalities and perfect compatibility. The minimal structure imposed on the model primitives is such that industry output increases in a firm's rivals' total output as well as in the expected network size. This leads to a generalized equilibrium existence treatment that includes guarantees for a nontrivial equilibrium, and some insight into possible multiplicity of equilibria. We formalize the concept of industry viability and show that it is always enhanced by having more firms in the market and/or by technological improvements. We also characterize the effects of market structure on industry performance, with an emphasis on departures from standard markets. As per-firm profits need not be monotonic in the number of competitors, we revisit the concept of free entry equilibrium for network industries. The approach relies on lattice-theoretic methods, which allow for a unified treatment of various general results in the literature on network goods. Several illustrative examples with closed-form solutions are also provided.

A number of technology products display positive network effects, and are used invariable quantities by heterogeneous customers. Examples include operating systems, infrastructureand back-end software, web services and networking equipment. This paper studies optimalnonlinear pricing for such products, under incomplete information, and with the threat of competitiveentry. Both homogeneous and heterogeneous network effects are modeled. Conditions underwhich a fulfilled-expectations contract exists and is unique are established. While network effectsgenerally raise price, it is shown that accompanying changes in consumption depend on the natureof the network effects - in some cases, it is optimal for the monopolist to induce no changes in usageacross customers, while in others cases, network effects raise the usage of all market participants.Optimal pricing is shown to include quantity discounts that increase with usage, and may also involvea nonlinear two-part tariff. These results highlight the impact of network effects on trade-offsbetween price discrimination and value creation, and have important managerial implications forpricing policy in technology markets.The need to deter competitive entry generally lowers profits for the monopolist, and increasescustomer surplus. When network effects are homogeneous across customers, the resulting entry-deterringmonopoly contract is a fixed fee and results in the socially optimal outcome. However,when the magnitude of heterogeneous network effects is relatively high, there are no changes intotal surplus induced by the entry threat, and the price changes merely cause a transfer of valuefrom the seller to its customers. The presence of network effects, and of a credible entry threat, arealso shown to increase distributional efficiency by reducing the disparity in relative value capturedby different customer types. Regulatory and policy implications of these results are discussed.