Advances in Mathematical Economics Volume 18 pp 135-140
A Characterization of Quasi-concave Function in View of the Integrability Theory
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Let g and u be C1-class real-valued functions that satisfy the Lagrange multiplier condition Du = λ g and Du ≠ 0. In this paper, we show that u is quasi-concave if and only if g satisfies an inequality which is related to the Bordered Hessian condition even if both of u and g are C1 rather than C2.
Key wordsIntegrability Inverse demand function Quasi-concavity Utility function