Jinlu Li, Strict Fréchet differentiability of metric projection operators in Hilbert spaces
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DOI: 10.23952/jnva.9.2025.5.07
Volume 9, Issue 5, 1 October 2025, Pages 755-780
Abstract. In this paper, we prove strict Fréchet differentiability of the metric projection operator onto closed balls in Hilbert spaces and onto positive cones in Euclidean spaces. We find the exact expressions for Fréchet derivatives. Since Fréchet differentiability implies Gâteaux directional differentiability, the results obtained in this paper strengthen some recent results obtained on the directional differentiability of the metric projection operator onto closed balls in Hilbert spaces and positive cones in Euclidean spaces and in 
How to Cite this Article:
J. Li, Strict Fréchet differentiability of metric projection operators in Hilbert spaces, J. Nonlinear Var. Anal. 9 (2025), 755-780.