Subdifferentiability of Convex Functions
The subdifferential is a fundamental tool in the analysis of nondifferentiable convex functions. In this chapter we discuss the properties of subdifferentials and the interplay between the subdifferential and the Legendre transform. Moreover, we establish the Brøndsted–Rockafellar theorem, which asserts that the graph of the subdifferential operator is dense in the domain of the separable sum of the function and its conjugate.
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