A counterexample for the Daugavet index of thickness in ${\ell }_1$-sums

Rainis Haller, Andre Ostrak

We give a negative answer to a question of Haller-Langemets-Lima-Nadel-Rueda Zoca asking whether, for all Banach spaces $X$ and $Y$, the Daugavet index of thickness satisfies \[ T(…