WEAKENING THE STRONG CONVEXITY OF PREFERENCES

In general models, the strong quasi-concavity of the objective function, sufficient for theoretical properties of demands in consumer theory, is often arbitrary. Then, weaker global concavity conditions that preserve such properties are desirable for such models. We propose a new global concavity condition that implies, for models with several nonlinear constraints: the local uniqueness and the smoothness of the decision functions, and the negativity of the generalised substitution matrix. This condition can be used to specify more general and more flexible economic models.