Nullity Restrictions and Comparative Static Analysis.

While homogeneity restrictions of optimal choice functions are well known in the context of neoclassical economic theory, the existence and implications of "homogeneity-like" restrictions in more general optimization models have not received much attention in the literature. The authors call such restrictions "nullity" restrictions since they involve the null space of the matrix of slopes of choice functions. The existence, nature, and implications of nullity restrictions are investigated in the context of a general optimization problem. This contributes to closing a major gap in the analysis of the implications of optimization for economic behavior. Copyright 1992 by Economics Department of the University of Pennsylvania and the Osaka University Institute of Social and Economic Research Association.