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Weakly compact operators and the strong* topology for a Banach space

Published online by Cambridge University Press:  08 December 2010

Antonio M. Peralta
Affiliation:
Departamento de Análisis Matemático, Facultad de Ciencias, Universidad de Granada, 18071 Granada, Spain (aperalta@ugr.es)
Ignacio Villanueva
Affiliation:
Departamento de Análisis Matemático, Facultad de Matemáticas, Universidad Complutense de Madrid, 28040 Madrid, Spain (ignaciov@mat.ucm.es)
J. D. Maitland Wright
Affiliation:
Mathematical Sciences, University of Aberdeen, Aberdeen AB24 3UE, UK (j.d.m.wright@abdn.ac.uk)
Kari Ylinen
Affiliation:
Department of Mathematics, University of Turku, 20014 Turku, Finland (ylinen@utu.fi)

Abstract

The strong* topology s*(X) of a Banach space X is defined as the locally convex topology generated by the seminorms x ↦ ‖Sx‖ for bounded linear maps S from X into Hilbert spaces. The w-right topology for X, ρ(X), is a stronger locally convex topology, which may be analogously characterized by taking reflexive Banach spaces in place of Hilbert spaces. For any Banach space Y , a linear map T : XY is known to be weakly compact precisely when T is continuous from the w-right topology to the norm topology of Y. The main results deal with conditions for, and consequences of, the coincidence of these two topologies on norm bounded sets. A large class of Banach spaces, including all C*-algebras and, more generally, all JB*-triples, exhibit this behaviour.

Type
Research Article
Copyright
Copyright © Royal Society of Edinburgh 2010

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