Non-expansive bijections to the unit ball of $\ell_1$-sum of strictly convex Banach spaces

Vladimir Kadets, Olesia Zavarzina

Published 2017-11-01Version 1

Extending recent results by Cascales, Kadets, Orihuela and Wingler (2016), Kadets and Zavarzina (2017), and Zavarzina (2017) we demonstrate that for every Banach space $X$ and every collection $Z_i, i\in I$ of strictly convex Banach spaces every non-expansive bijection from the unit ball of $X$ to the unit ball of sum of $Z_i$ by $\ell_1$ is an isometry.