We consider how the outputs of the Kadison transitivity theorem and Gelfand–Naimark–Segal (GNS) construction may be obtained in families when the initial data are varied. More precisely, for the Kadison transitivity theorem, we prove that for any nonzero irreducible representation [Formula: see text] of a [Formula: see text]algebra [Formula: see text] and [Formula: see text], there exists a continuous function [Formula: see text] such that [Formula: see text] for all [Formula: see text], where [Formula: see text] is the set of pairs of [Formula: see text]tuples [Formula: see text] such that the components of [Formula: see text] are linearly independent. Versions of this result where [Formula: see text] maps into the selfadjoint or unitary elements of [Formula: see text] are also presented. Regarding the GNS construction, we prove that given a topological [Formula: see text]algebra fiber bundle [Formula: see text], one may construct a topological fiber bundle [Formula: see text] whose fiber over [Formula: see text] is the space of pure states of [Formula: see text] (with the norm topology), as well as bundles [Formula: see text] and [Formula: see text] whose fibers [Formula: see text] and [Formula: see text] over [Formula: see text] are the GNS Hilbert space and closed left ideal, respectively, corresponding to [Formula: see text]. When [Formula: see text] is a smooth fiber bundle, we show that [Formula: see text] and [Formula: see text] are also smooth fiber bundles; this involves proving that the group of ∗automorphisms of a [Formula: see text]algebra is a Banach Lie group. In service of these results, we review the topology and geometry of the pure state space. A simple noninteracting quantum spin system is provided as an example illustrating the physical meaning of some of these results.
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Fractional Hardytype and trace theorems for nonlocal function spaces with heterogeneous localization
This work aims to prove a Hardytype inequality and a trace theorem for a class of function spaces on smooth domains with a nonlocal character. Functions in these spaces are allowed to be as rough as an [Formula: see text]function inside the domain of definition but as smooth as a [Formula: see text]function near the boundary. This feature is captured by a norm that is characterized by a nonlocal interaction kernel defined heterogeneously with a special localization feature on the boundary. Thus, the trace theorem we obtain here can be viewed as an improvement and refinement of the classical trace theorem for fractional Sobolev spaces [Formula: see text]. Similarly, the Hardytype inequalities we establish for functions that vanish on the boundary show that functions in this generalized space have the same decay rate to the boundary as functions in the smaller space [Formula: see text]. The results we prove extend existing results shown in the Hilbert space setting with p = 2. A Poincarétype inequality we establish for the function space under consideration together with the new trace theorem allows formulating and proving wellposedness of a nonlinear nonlocal variational problem with conventional local boundary condition.
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 NSFPAR ID:
 10332069
 Date Published:
 Journal Name:
 Analysis and Applications
 Volume:
 20
 Issue:
 03
 ISSN:
 02195305
 Page Range / eLocation ID:
 579 to 614
 Format(s):
 Medium: X
 Sponsoring Org:
 National Science Foundation
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