We consider a general framework of optimal mechanism design under adverse selection and ambiguity about the type distribution of agents. We prove the existence of optimal mechanisms under minimal assumptions on the contract space and prove that centralized contracting implemented via mechanisms...

In John Nash’s proofs for the existence of (Nash) equilibria basedon Brouwer’s theorem, an iteration mapping is used. A continuous—time analogue of the same mapping has been studied even earlier byBrown and von Neumann. This differential equation has recently beensuggested as a plausible...

We study economies in which agents face Knightian uncertainty about state prices. Knightian uncertainty leads naturally to nonlinear expectations. We introduce a corresponding equilibrium concept with sublinear prices and prove that equilibria exist under weak conditions. In general, such...