Existence of Competitive Equilibria in Economies with a Measure Space of Consumers and

1 A solution to a long-standing open problem is given by extending Aumann's Walrasian equilibrium existence result for a pure exchange economy with a continuum of consumers [2] to the situation where preferences are allowed to depend upon the consumption profile (as well as the price vector). Our extension includes Schmeidler's existence results for a game with a continuum of players [38]. We study the existence of competitive equilibria and asymptotic competitive equilibria. The latter kind of equilibrium, which is introduced here as a natural extension of Aumann's notion, turns out to exist for a larger, more interesting class of consumption externalities. Specializations of our main results yield the original existence results of Aumann and Schmeidler

Existence of Competitive Equilibria in Economies with a Measure Space of Consumers and

Alta Matematica is gratefully acknowledged

Contractually Stable Alliances

We analyze how dierent rules for exiting an alliance (simple majority, unanimity or unanimity with side payments) will aect the formation of strategic alliances. We find that no alliance structure is contractually stable under the simple majority rule. Once unanimous consent is required, asymmetric alliance structures consisting of two alliances are contractually stable. In addition, the grand alliance which is the ecient structure is stable. Allowing for side payments to compensate former partners improves eciency. Finally, we show that dierent rules of exit may coexist in dierent alliances in the long run

Optimization in Multi-Issue Negotiation Settings with

In recent years, certain formalizations of combinatorial negotiation settings, most notably combinatorial auctions, have been intensively studied in our community. A pervasive assumption has been that of no externalities: the agents deciding on a variable (such as whether a trade takes place between them) are the only ones affected by how this variable is set. To date, there has been no widely studied formalization of combinatorial negotiation settings with externalities