Directional Differentiability of the Metric Projection in Hilbert Space
نویسنده
چکیده
The differentiability properties of the metric projection Pc on a closed convex set C in Hilbert space are characterized in terms of the smoothness type of the boundary of C. Our approach is based on using variational type second derivatives as a sufficiently flexible tool to describe the boundary struc ture of the set C with regard to the differentiability of Pc. We extend results by R.B. Holmes and S. Fitzpatrick and R.R. Phelps.
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