Strategic Interaction and Networks

This paper brings a general network analysis to a wide class of economic games. A network, or interaction matrix, tells who directly interacts with whom. A major challenge is determining how network structure shapes overall outcomes. We have a striking result. Equilibrium conditions depend on a single number: the lowest eigenvalue of a network matrix. Combining tools from potential games, optimization, and spectral graph theory, we study games with linear best replies and characterize the Nash and stable equilibria for any graph and for any impact of players’ actions. When the graph is sufficiently absorptive (as measured by this eigenvalue), there is a unique equilibrium. When it is less absorptive, stable equilibria always involve extreme play where some agents take no actions at all. This paper is the first to show the importance of this measure to social and economic outcomes, and we relate it to different network link patterns.Networks, potential games, lowest eigenvalue, stable equilibria, asymmetric equilibria

Contracts, Hold-Up, and Exports: Textiles and Opium in Colonial India

Trade and export, it is argued, spur economic growth. This paper studies the microeconomics of exporting. We build a heuristic model of transactions between exporters and producers and relate it to East India Company operations in colonial Bengal. Our model and the historical record stress two difficulties: the exporter and its agents might not uphold pricing agreements, and producers might not honor sales contracts. The model shows when procurement succeeds or fails, highlighting the tension between these two hold-up problems. We analyze several cases including the East India Company's textile venture, the famous Opium Monopoly, and present-day contract farming.

Contracts, Hold-Up, and Exports: Textiles and Opium in Colonial India

Trade and export, it is argued, spur economic growth. This paper studies the microeconomics of exporting. We build a heuristic model of transactions between exporters and producers and relate it to East India Company operations in colonial Bengal. Our model and the historical record stress two difficulties: the exporter and its agents might not uphold pricing agreements, and producers might not honor sales contracts. The model shows when procurement succeeds or fails, highlighting the tension between these two hold-up problems. We analyze several cases including the East India Company's textile venture, the famous Opium Monopoly, and present-day contract farming.

Vertical Foreclosure and Specific Investments

Are vertical mergers efficient or restraints to trade? This paper examines this long-standing question in a new setting and reaches new conclusions. We consider a realistic environment where downstream firms can make specific investments in several suppliers at once. In keeping with the "Chicago School" of regulation, we assume inputs are exchanged efficiently regardless of the ownership structure. Nevertheless, we find that vertical merger can be inefficient. A merged firm has an incentive to manipulate its ex ante investments to increase the ex post revenues of its supply unit. It will increase its investment in its internal supplier and decrease its investment in an external supplier relative to the efficient level of investments. The "skewing" is reinforced in equilibrium by other buyers who respond by skewing their own investments. The result is a reduction in the variety of inputs purchased by downstream firms. We relate the theory to studies of vertical mergers in pharmaceuticals and cable television.

Games Played on Networks

This chapter studies games played on fixed networks. These games capture a wide variety of economic settings including local public goods, peer effects, and technology adoption. We establish a common analytical framework to study a wide game class. We unearth new connections between games in the literature and in particular between those with binary actions, like coordination and best-shot games, and those with continuous actions and linear best replies. We review and advance existing results by showing how they tie together within the common framework. We discuss the game-theoretic underpinnings of key notions including Bonacich centrality, maximal independent sets, and the lowest and largest eigenvalue. We study the interplay of individual heterogeneity and the network and we develop a new notion - interdependence - to analyze how a shock to one agent affects the action of another agent. We outline directions for future research

Rumors and Social Networks

Why do people spread rumors? This paper studies the transmission of possibly false information---by rational agents who seek the truth. Unbiased agents earn payoffs when a collective decision is correct in that it matches the true state of the world, which is initially unknown. One agent learns the underlying state and chooses whether to send a true or false message to her friends and neighbors who then decide whether or not to transmit it further. The papers hows how a social network can serve as a filter. Agents block messages from parts of the network that contain many biased agents; the messages that circulate may be incorrect but sufficiently informative as to the correct decision

Matching structure and bargaining outcomes in buyer–seller networks

We examine the relationship between the matching structure of a bipartite (buyer-seller) network and the (expected) shares of the unit surplus that each connected pair in this network can create. We show that in different bargaining environments, these shares are closely related to the Gallai-Edmonds Structure Theorem. This theorem characterizes the structure of maximum matchings in an undirected graph. We show that the relationship between the (expected) shares and the tructure Theorem is not an artefact of a particular bargaining mechanism or trade centralization. However, this relationship does not necessarily generalize to non-bipartite networks or to networks with heterogeneous link values

Limits on Relief through Constrained Exchange on Random Graphs

Agents are represented by nodes on a random graph (e.g., small world or truncated power law). Each agent is endowed with a zero-mean random value that may be either positive or negative. All agents attempt to find relief, i.e., to reduce the magnitude of that initial value, to zero if possible, through exchanges. The exchange occurs only between agents that are linked, a constraint that turns out to dominate the results. The exchange process continues until a Pareto equilibrium is achieved. Only 40%-90% of the agents achieved relief on small world graphs with mean degree between 2 and 40. Even fewer agents achieved relief on scale-free like graphs with a truncated power law degree distribution. The rate at which relief grew with increasing degree was slow, only at most logarithmic for all of the graphs considered; viewed in reverse, relief is resilient to the removal of links.Comment: 8 pages, 2 figures, 22 references Changes include name change for Lory A. Ellebracht (formerly Cooperstock, e-mail address stays the same), elimination of contractions and additional references. We also note that our results are less surprising in view of other work now cite

Pricing, cost recovery, and production efficiency in transport : a critique

The purpose of this paper is to assess the efficacy of optimal pricing formulas for pricing and cost recovery and to develop a general framework within which to analyze the performance of public transport. Five sources of inefficiency in public transport are discussed: (a) the goals of the enterprise or the regulation of its operations; (b) the structure of the output market; (c) the control mechanism between government and the enterprise; (c) the managerial incentive structure; and (d) the conditions of employment. Even when public enterprises are bent on maximizing consumer welfare, costs are not necessarily minimized. Lack of competition may also exacerbate the problem of asymmetric information between owners and managers. Owners of public firms are unlikely to exert pressure on public enterprises to operate efficiently. And public firms may be protected from insolvency by"soft"budget constraints.Economic Theory&Research,Environmental Economics&Policies,Banks&Banking Reform,Municipal Financial Management,Public Sector Economics&Finance

Risk-Sharing Networks

This paper considers the formation of risk-sharing networks. Following empirical findings, we build a model where risk-sharing takes place between pairs of individuals. We ask what structures emerge when pairs can agree to form links, but people cannot coordinate links across a population. We consider a benchmark model where identical individuals commit to share their monetary holdings equally with linked partners. We compare efficient networks to equilibrium networks. Efficient networks can (indirectly) connect all individuals and involve full insurance. However, equilibrium networks connect fewer individuals. There is an externality: when breaking a link individuals do not take into account the negative effect on others distant in the network. The network formation process can lead identical individuals to be in different positions and thus have different risk-sharing outcomes. These results may help explain empirical findings that risk-sharing is often not symmetric or complete