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

Autor:	Enrique Llorens-Fuster, Jesús Ferrer
Rok vydání:	2020
Předmět:	Unit sphere Combinatorics General Mathematics 010102 general mathematics 0101 mathematics Fixed point 01 natural sciences Mathematics
Zdroj:	The American Mathematical Monthly. 127:354-358
ISSN:	1930-0972 0002-9890
DOI:	10.1080/00029890.2020.1704168
Popis:	It is known that some particular self-mappings of the closed unit ball Bl2 of l2 with no fixed points cannot be nonexpansive with respect to any renorming of l2. We give here a short proof of this ...
Databáze:	OpenAIRE
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