The concept of the restricted cost function provides a dual approach to the analysis of short-run technology. It allows also, under curvature restrictions, inference of the different possible equilibria, according to constraints on the firms. Moreover, in this paper, the properties of the restricted cost function are spelled out. Substitution possibilities related to the different regimes are also derived from the restricted cost function. This theoretical framework is applied to characterize the French cereal-producing sector by using a cross-section of farms.