Identifying derivations through the spectra of their values

M. Brešar, B. Magajna, Š. Špenko

We consider the relationship between derivations $d$ and $g$ of a Banach algebra $B$ that satisfy $\s(g(x)) \subseteq \s(d(x))$ for every $x\in B$, where $\s(\, . \,)$ stands for t…