In a general setting of private information, the possibility (impossibility) theorem is said to be valid, if a balanced and ex post efficient mechanism exists (does not exist) which agents voluntarily participate at. Possibility and impossibility results are called robust if they hold for all...

Nowadays many employers offer their employees the possibility of an insurance against too large losses in income when retiring or becoming disabled. This paper models the optimization problem of the employer when setting up such a so-called pension fund. not surprisingly, it turns out that the...

We show that in oligopolistic markets the social choice correspondence which selects all socially efficient outcomes is Nash implementable if the number of firms is at least two. Thus, monopoly regulation whenever consumers are favored by the designer or the society is the only framework, among...

This paper shows that in an incomplete information situation if the set of states of the society which occur with positive probability satisfies 'connection' condition, then closure condition will be satisfied by all social choice sets. It then follows from Jackson's (1991) two fundamental...

We investigate the issue of implementation via individually rational ex-post budget-balanced Bayesian mechanisms. We demonstrate that all social choice rules that generate a nonnegative ex-ante surplus, including ex-post efficient ones, can generically be implemented via such mechanisms. The...

Nowadays many employers offer their employees the possibility of an insurance against too large losses in income when retiring or becoming disabled. This paper models the optimization problem of the employer when setting up such a so-called pension fund. Not surprisingly, it turns out that the...