Two distance preservers of generalized numerical radii
Jor-Ting Chan, Kong Chan · Linear and Multilinear Algebra · 2013
Let be a complex Hilbert space and let be the set of all bounded linear operators on . For every , the joint numerical radius of is denoted by . We give a description for surjective mappings such that for all , when is infinite-dimensional. This complements a recent result of Li and Poon for such mappings when is finite-dimensional. We also study the Davis–Wielandt radius, , of . A description for surjective mappings such that for all is also given.