A Short Proof that Some Mappings of the Unit Ball of ℓ2 Are Never Nonexpansive

Jesús Ferrer, Enrique Llorens-Fuster. A Short Proof that Some Mappings of the Unit Ball of ℓ2 Are Never Nonexpansive. The American Mathematical Monthly, 127(4):354-358, 2020. [doi]

Abstract

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