Regular Coderivative and Graphical Derivative of the Metric Projection onto closed Balls in Hilbert spaces

Abstract

In this paper, we first establish a formula for exactly computing the regular coderivative of the metric projection operator onto closed balls $r\mathbb{B}$ centered at the origin in Hilbert spaces. Then, this result is extended to metric projection operator onto any closed balls $\mathbb{B}(c,r)$, which has center $c$ in Hilbert space $H$ and with radius $r>0$. Finally, we give the formula for calculating the graphical derivative of the metric projection operator onto closed balls with center at arbitrarily given point in Hilbert spaces.