Displaying 421 – 440 of 444

Showing per page

Pseudodifferential operators on non-quasianalytic classes of Beurling type

C. Fernández, A. Galbis, D. Jornet (2005)

Studia Mathematica

We introduce pseudodifferential operators (of infinite order) in the framework of non-quasianalytic classes of Beurling type. We prove that such an operator with (distributional) kernel in a given Beurling class ( ω ) ' is pseudo-local and can be locally decomposed, modulo a smoothing operator, as the composition of a pseudodifferential operator of finite order and an ultradifferential operator with constant coefficients in the sense of Komatsu, both operators with kernel in the same class ( ω ) ' . We also...

Pseudometrics on Ext-semigroups

Changguo Wei, Xiangmei Zhao, Shudong Liu (2020)

Czechoslovak Mathematical Journal

This paper considers certain pseudometric structures on Ext-semigroups and gives a unified characterization of several topologies on Ext-semigroups. It is demonstrated that these Ext-semigroups are complete topological semigroups. To this end, it is proved that a metric induces a pseudometric on a quotient space with respect to an equivalence relation if it has certain invariance. We give some properties of this pseudometric space and prove that the topology induced by the pseudometric coincides...

Pseudotopologies with applications to one-parameter groups, von Neumann algebras, and Lie algebra representations

Jan Rusinek (1993)

Studia Mathematica

For any pair E,F of pseudotopological vector spaces, we endow the space L(E,F) of all continuous linear operators from E into F with a pseudotopology such that, if G is a pseudotopological space, then the mapping L(E,F) × L(F,G) ∋ (f,g) → gf ∈ L(E,G) is continuous. We use this pseudotopology to establish a result about differentiability of certain operator-valued functions related with strongly continuous one-parameter semigroups in Banach spaces, to characterize von Neumann algebras, and to establish...

Pták homomorphism theorem revisited

J. R. Ferrer, M. López Pellicer, L. M. Sánchez Ruiz (2000)

Czechoslovak Mathematical Journal

Rodrigues’ extension (1989) of the classical Pták’s homomorphism theorem to a non-necessarily locally convex setting stated that a nearly semi-open mapping between a semi-B-complete space and an arbitrary topological vector space is semi-open. In this paper we study this extension and, as a consequence of the results obtained, provide an improvement of Pták’s homomorphism theorem.

Pure states on Jordan algebras

Jan Hamhalter (2001)

Mathematica Bohemica

We prove that a pure state on a C * -algebras or a JB algebra is a unique extension of some pure state on a singly generated subalgebra if and only if its left kernel has a countable approximative unit. In particular, any pure state on a separable JB algebra is uniquely determined by some singly generated subalgebra. By contrast, only normal pure states on JBW algebras are determined by singly generated subalgebras, which provides a new characterization of normal pure states. As an application we contribute...

Currently displaying 421 – 440 of 444