The present monograph is a synthesis of what has been contributed during the last decade to the analysis of market demand in large econ omies where consumers may have non-convex preference relations. Al though research in this field has not yet come to an end there exists a variety of interesting results, established in different frameworks by means of different conceptual and formal tools. a It is my aim to give comprehensive treatment of the existing lit erature including my own contributions. In working out differences and interrelations of the various ap proaches I adopted and modified...