$k$-smoothness on polyhedral Banach spaces
Volume 169 / 2022
                    
                    
                        Colloquium Mathematicum 169 (2022), 25-37                    
                                        
                        MSC: Primary 46B20, Secondary 47L05.                    
                                        
                        DOI: 10.4064/cm8520-4-2021                    
                                            
                            Published online: 24 January 2022                        
                                    
                                                Abstract
We characterize $k$-smoothness of an element on the unit sphere of a finite-dimensional polyhedral Banach space. Then we study $k$-smoothness of an operator $T \in \mathbb {L}(\ell _{\infty }^n,\mathbb {Y}),$ where $\mathbb {Y}$ is a two-dimensional Banach space with the additional condition that $T$ attains its norm at each extreme point of $B_{\ell _{\infty }^{n}}.$ We also characterize $k$-smoothness of an operator from $\ell _{\infty }^3$ to $\ell _{1}^3.$
 
             
                                                             
                                                             
                                                             
                                                             
                                                             
                                                             
                                                         
                                                            