In the random assignment problem, objects are randomly assigned to agents keeping in view the agents’ preferences over objects. A random assignment specifies the probability of an agent getting an object. We examine the structural and computational aspects of ex post efficiency of random assignments. We first show that whereas an ex post efficient assignment can be computed easily, checking whe...

We present a model of N-player contracting with transaction costs and endogenous property rights. Ex ante agreed surplus sharing can be altered ex post, after irreversible investments in production (characterised by the generalised Cobb-Douglas production function). The actual surplus sharing is determined ex post, after each player has chosen a costly action to alter the surplus sharing in his...

In this paper, we provide an axiomatic characterization of social welfare functions for uncertain incomes. Our most general result is that a small number of reasonable assumptions regarding welfare orderings under uncertainty rule out pure ex ante as well as pure ex post evaluations. Any social welfare function that satisfies these axioms should lie strictly between the ex ante and the ex post ...

The paper considers a hold-up model where only one of n future trading opportunities will prove to be efficient, and where ex post renegotiation of the ex ante contract cannot be prevented. As the environment becomes more complex (n→S ), the outcome under any message-contingent long-term contract converges to that of the ‘‘incomplete contracting’’ model where trade is contractible ex post, but ...

1 We consider a general mechanism design setting where each agent can acquire (covert) information before participating in the mechanism. The central question is whether a mechanism exists that provides the efficient incentives for information acquisition ex-ante and implements the efficient allocation conditional on the private information ex-post. It is shown that in every private value envir...