This work presents a theory for games with symmetric externali-ties, where the externalities by any one player imposed on another is same as the vice versa. The theory connects a social optimum outcome with its eigen-equilibrium, a Nash equilibrium of a game that is attained by transforming a social optimum. An implication of the theory is that social optimum could be implemented in a way with ...

We consider a “Social Group” of networked nodes, seeking a “universe” of segments. Each node has subset of the universe, and access to an expensive resource for downloading data. Alternatively, nodes can also acquire the universe by exchanging segments among themselves, at low cost, using a local network interface. While local exchanges ensure minimum cost, “free riders” in the group can exploi...

Social network research has begun to take advantage of finegrained communications regarding coordination, decisionmaking, and knowledge sharing. These studies, however, have not generally analyzed how external events are associated with a social network’s structure and communicative properties. Here, we study how external events are associated with a network’s change in structure and communicat...

We study the social welfare optimum for a vertically differentiated duopoly under partial market coverage and variable costs. Costs are specified as linear in quantity and quadratic in quality. We demonstrate that the spread of product quality observed under a profit maximizing duopoly is too high, relative to the social welfare optimum. We also find that high quality firms in a duopoly will ha...

This paper extends the recent investigation of Tahvonen and Withagen (1996, Journal of Economic Dynamics and Control 20, 1775}1795) for costly and thus sluggish instead of instantaneous reductions in emissions. In addition to the social optimum, the paper investigates the competitive equilibrium. This plausible extension allows to derive limit cycles as the outcome for both, the social optimum ...