Traces on operator ideals and arithmetic means

dc.creatorKaftal, Victor
dc.creatorWeiss, Gary
dc.date2007-07-22
dc.date.accessioned2026-07-07T08:19:35Z
dc.date.available2026-07-07T08:19:35Z
dc.descriptionThis article - a part of a multipaper project investigating arithmetic mean ideals - investigates the codimension of commutator spaces [I, B(H)] of operator ideals on a separable Hilbert space, i.e., ``How many traces can an ideal support?" We conjecture that the codimension can be only zero, one, or infinity. Using the arithmetic mean (am) operations on ideals introduced by Dykema, Figiel, Weiss, and Wodzicki, and the analogous am operations at infinity that we develop in this article, the conjecture is proven for all ideals not contained in the largest am-infinity stable ideal and not containing the smallest am-stable ideal. It is also proven for all soft-edged ideals (i.e., I= IK(H)) and all soft-complemented ideals (i.e., I= I/K(H)), which include many classical operator ideals. In the process, we prove that an ideal of trace class operators supports a unique trace (up to scalar multiples) if and only if it is am-infinity stable and that, for a principal ideal, am-infinity stability is equivalent to regularity at infinity of the sequence of s-numbers of the generator. Furthermore, we apply trace extension methods to two problems on elementary operators studied by V. Shulman and to Fuglede-Putnam type problems of the second author.
dc.description41 pages, 1 figure
dc.identifierhttps://arxiv.org/abs/0707.3169
dc.identifierhttp://arxiv.org/abs/0707.3169
dc.identifier.urihttp://salesiana.dossiersoluciones.com/handle/123456789/134808
dc.subjectFunctional Analysis
dc.subjectOperator Algebras
dc.subject47B47, 47B10, 47L20 (Primary); 46A45, 46B45 (Secondary)
dc.titleTraces on operator ideals and arithmetic means
dc.typetext

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