In search of convexity: Diagonals and numerical ranges

Result code in IS VaVaI

<a href="https://www.isvavai.cz/riv?ss=detail&h=RIV%2F67985840%3A_____%2F21%3A00544892" target="_blank" >RIV/67985840:_____/21:00544892 - isvavai.cz</a>

Result on the web

<a href="https://doi.org/10.1112/blms.12480" target="_blank" >https://doi.org/10.1112/blms.12480</a>

DOI - Digital Object Identifier

<a href="http://dx.doi.org/10.1112/blms.12480" target="_blank" >10.1112/blms.12480</a>

Result language

angličtina

Original language name

In search of convexity: Diagonals and numerical ranges

Original language description

We show that the set of all possible constant diagonals of a bounded Hilbert space operator is always convex. This, in particular, answers an open question of Bourin (2003). Moreover, we show that the joint numerical range of a commuting operator tuple is, in general, not convex, which fills a gap in the literature. We also prove that the Asplund–Ptak numerical range (which is convex for pairs of operators) is, in general, not convex for tuples of operators.

Czech name

—

Czech description

—

Type

J_imp - Article in a specialist periodical, which is included in the Web of Science database

CEP classification

—

OECD FORD branch

10101 - Pure mathematics

Project

<a href="/en/project/GX20-31529X" target="_blank" >GX20-31529X: Abstract convergence schemes and their complexities</a><br>

Continuities

I - Institucionalni podpora na dlouhodoby koncepcni rozvoj vyzkumne organizace

Publication year

2021

Confidentiality

S - Úplné a pravdivé údaje o projektu nepodléhají ochraně podle zvláštních právních předpisů

Name of the periodical

Bulletin of the London Mathematical Society

ISSN

0024-6093

e-ISSN

1469-2120

Volume of the periodical

53

Issue of the periodical within the volume

4

Country of publishing house

GB - UNITED KINGDOM

Number of pages

14

Pages from-to

1016-1029

UT code for WoS article

000625165700001

EID of the result in the Scopus database

2-s2.0-85101917684