On the existence of optimal contract mechanisms for incomplete information principal-agent models

In a series of papers, F.H. Page presented existence results for optimal contract selection mechanisms for a number of principal-agent models [9, 12, 13]. These models involve both moral hazard and incomplete information aspects (in the sense of e.g. Harsanyi [6] and Meyerson [8]). A quite related existence result was also given by Page for the existence of an optimal Stackelberg strategy in a game with incomplete information [10]. In some form or another, all these models deal with the maximization of the principal's expected utility function Z