Associative and Lie subalgebras of finite codimension
Given a complex Hilbert space H, we study the manifold of algebraic elements in . We represent as a disjoint union of closed connected subsets M of Z each of which is an orbit under the action of G, the group of all C*-algebra automorphisms of Z. Those orbits M consisting of hermitian algebraic elements with a fixed finite rank r, (0< r<∞) are real-analytic direct submanifolds of Z. Using the C*-algebra structure of Z, a Banach-manifold structure and a G-invariant torsionfree affine...
Ad un'algebra di von Neumann separabile , in forma standard su di uno spazio di Hilbert , si associa la algebra definita come la algebra costituita dai punti fissi dell'algebra di Cuntz generalizzata mediante l'azione canonica del gruppo degli unitari di . Si dà una caratterizzazione di nel caso in cui è un fattore iniettivo. In seguito, come applicazione della teoria dei sistemi asintoticamente abeliani, si mostra che, se è uno stato vettoriale normale e fedele di , la restrizione...
We show several examples of n.av̇alued fields with involution. Then, by means of a field of this kind, we introduce “n.aḢilbert spaces” in which the norm comes from a certain hermitian sesquilinear form. We study these spaces and the algebra of bounded operators which are defined on them and have an adjoint. Essential differences with respect to the usual case are observed.
A Banach space has Pełczyński’s property (V) if for every Banach space every unconditionally converging operator is weakly compact. H. Pfitzner proved that -algebras have Pełczyński’s property (V). In the preprint (Krulišová, (2015)) the author explores possible quantifications of the property (V) and shows that spaces for a compact Hausdorff space enjoy a quantitative version of the property (V). In this paper we generalize this result by quantifying Pfitzner’s theorem. Moreover, we...