Plasticity of the unit ball of $c$ and $c_0$

Abstract

We prove the plasticity of the unit ball of c. That is, we show that every non-expansive bijection from the unit ball of c onto itself is an isometry. We also demonstrate a slightly weaker property for the unit ball of c 0 -we prove that a non-expansive bijection is an isometry, provided that it has a continuous inverse. 2020 Mathematics Subject Classification. 46B20, 47H09.