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Some remarks on Gleason measures

P. De Nápoli, M. C. Mariani (2007)

Studia Mathematica

This work is devoted to generalizing the Lebesgue decomposition and the Radon-Nikodym theorem to Gleason measures. For that purpose we introduce a notion of integral for operators with respect to a Gleason measure. Finally, we give an example showing that the Gleason theorem does not hold in non-separable Hilbert spaces.

Some remarks on quantum and braided group gauge theory

Shahn Majid (1997)

Banach Center Publications

We clarify some aspects of quantum group gauge theory and its recent generalisations (by T. Brzeziński and the author) to braided group gauge theory and coalgebra gauge theory. We outline the diagrammatic version of the braided case. The bosonisation of any braided group provides us a trivial principal bundle in three ways.

Sommes de commutateurs dans les algèbres de von Neumann finies continues

Thierry Fack, Pierre de La Harpe (1980)

Annales de l'institut Fourier

Soit M une algèbre de von Neumann finie. Nous montrons que l’espace des sommes finies de commutateurs de M coïncide avec le noyau de la trace centrale. Si M est un facteur, il en résulte par exemple que tout élément est une combinaison linéaire finie de projecteurs de dimension 1 / 2 . Nous montrons aussi dans ce cas que le groupe dérivé de G L ( M ) coïncide avec le noyau du déterminant de Fuglede-Kadison.

Spectral distribution of the free Jacobi process associated with one projection

Nizar Demni, Taoufik Hmidi (2014)

Colloquium Mathematicae

Given an orthogonal projection P and a free unitary Brownian motion Y = ( Y ) t 0 in a W*-non commutative probability space such that Y and P are *-free in Voiculescu’s sense, we study the spectral distribution νₜ of Jₜ = PYₜPYₜ*P in the compressed space. To this end, we focus on the spectral distribution μₜ of the unitary operator SYₜSYₜ*, S = 2P - 1, whose moments are related to those of Jₜ via a binomial-type expansion already obtained by Demni et al. [Indiana Univ. Math. J. 61 (2012)]. In this connection,...

Spectral isometries

Martin Mathieu (2005)

Banach Center Publications

In this survey, we summarise some of the recent progress on the structure of spectral isometries between C*-algebras.

Spectral subspaces and non-commutative Hilbert transforms

Narcisse Randrianantoanina (2002)

Colloquium Mathematicae

Let G be a locally compact abelian group and ℳ be a semifinite von Neumann algebra with a faithful semifinite normal trace τ. We study Hilbert transforms associated with G-flows on ℳ and closed semigroups Σ of Ĝ satisfying the condition Σ ∪ (-Σ) = Ĝ. We prove that Hilbert transforms on such closed semigroups satisfy a weak-type estimate and can be extended as linear maps from L¹(ℳ,τ) into L 1 , ( , τ ) . As an application, we obtain a Matsaev-type result for p = 1: if x is a quasi-nilpotent compact operator...

Currently displaying 41 – 60 of 108