## Topological Methods in Nonlinear Analysis

### Around Ulam's question on retractions

#### Abstract

It is known that the unit ball in infinitely dimensional Hilbert space can be retracted onto its boundary via a lipschitzian mapping. The magnitude of Lipschitz constant is only roughly estimated. The note contains a number of observations connected to this result and opens some new problems.

#### Article information

Source
Topol. Methods Nonlinear Anal., Volume 40, Number 1 (2012), 215-224.

Dates
First available in Project Euclid: 21 April 2016

https://projecteuclid.org/euclid.tmna/1461243460

Mathematical Reviews number (MathSciNet)
MR3026109

Zentralblatt MATH identifier
1290.47054

#### Citation

Chaoha, Phichet; Goebel, Kazimierz; Termwuttipong, Imchit. Around Ulam's question on retractions. Topol. Methods Nonlinear Anal. 40 (2012), no. 1, 215--224. https://projecteuclid.org/euclid.tmna/1461243460

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