Arens-regularity of algebras arising from tensor norms.
Aspects of the theory of derivations
We survey some old and new results in the theory of derivations on Banach algebras. Although our overview is broad ranging, our principal interest is in recent results concerning conditions on a derivation implying that its range is contained in the radical of the algebra.
Automatische Stetigkeitseigenschaften einiger Klassen linearer Operatoren.
Automorphisms and derivations on a universally complete complex -algebra.
Axiomatic theory of spectrum III: semiregularities
We introduce and study the notions of upper and lower semiregularities in Banach algebras. These notions generalize the previously studied notion of regularity - a class is a regularity if and only if it is both upper and lower semiregularity. Each semiregularity defines in a natural way a spectrum which satisfies a one-way spectral mapping property (the spectrum defined by a regularity satisfies the both-ways spectral mapping property).