Differential characterization of quasi-concave functions without twice differentiability
Differential characterization of quasi-concave functions without twice differentiability
This paper presents a necessary and sufficient condition for a real-valued function defined on an open and convex subset of a Banach space to be quasi-concave, and a sufficient condition for such a function to be strictly quasi-concave.These conditions are applicable to continuously differentiable functions that satisfy a mild additional …