Mathematics - Research News

On $J$ -frames related to maximal definite subspaces

 Mathematics - Research News
 16 January 2019
Alan Kamuda, Sergii Kuzhel. Source: Annals of Functional Analysis, Volume 10, Number 1, 106--121.Abstract: We propose a definition of frames in Krein spaces which generalizes the concept of $J$ -frames defined relatively recently by Giribet, Maestripieri, Martínez-Pería, and Massey. The difference...

Unitary representations of infinite wreath products

 Mathematics - Research News
 16 January 2019
Robert P. Boyer, Yun S. Yoo. Source: Annals of Functional Analysis, Volume 10, Number 1, 97--105.Abstract: Using $C^{*}$ -algebraic techniques and especially AF-algebras, we present a complete classification of the continuous unitary representations for a class of infinite wreath product groups....

Cyclic weighted shift matrix with reversible weights

 Mathematics - Research News
 16 January 2019
Peng-Ruei Huang, Hiroshi Nakazato. Source: Annals of Functional Analysis, Volume 10, Number 1, 72--80.Abstract: We characterize a class of matrices that is unitarily similar to a complex symmetric matrix via the discrete Fourier transform. ...

Unique expectations for discrete crossed products

 Mathematics - Research News
 16 January 2019
Vrej Zarikian. Source: Annals of Functional Analysis, Volume 10, Number 1, 60--71.Abstract: Let $G$ be a discrete group acting on a unital $C^{*}$ -algebra $\mathcal{A}$ by $*$ -automorphisms. We characterize (in terms of the dynamics) when the inclusion...

On the structure of the dual unit ball of strict $u$ -ideals

 Mathematics - Research News
 16 January 2019
Julia Martsinkevitš, Märt Põldvere. Source: Annals of Functional Analysis, Volume 10, Number 1, 46--59.Abstract: It is known that if a Banach space $Y$ is a $u$ -ideal in its bidual $Y^{\ast\ast}$ with respect to the canonical projection on the third dual $Y^{\ast\ast\ast}$ , then $Y^{\ast}$...

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