Spectral properties of (m;n)-isosymmetric multivariable operators

TL;DR

This paper introduces and studies the properties of a new class of multivariable operators called $(m,n)$-isosymmetric operators, generalizing existing concepts and analyzing their spectral characteristics.

Contribution

The paper defines $(m,n)$-isosymmetric multivariable operators, explores their fundamental properties, and examines how they behave under certain perturbations and their spectral features.

Findings

$(m,n)$-isosymmetric operators generalize $m$-isometric and $n$-isosymmetric operators.

Sum of an $(m,n)$-isosymmetric operator and a nilpotent operator yields a new $(m',n')$-isosymmetric operator.

Results on the joint approximate spectrum of these operators are provided.

Abstract

Inspired by recent works on $m$-isometric and $n$-symmetric multivariables operators on Hilbert spaces, in this paper we introduce the class of $(m, n)$-isosymmetric multivariables operators. This new class of operators emerges as a generalization of the $m$-isometric and $n$-isosymmetric multioperators. We study this class of operators and give some of their basic properties. In particular, we show that if ${\bf \large R} \in {\mathcal B}^{(d)}({\mathcal H})$ is an $(m,n )$-isosymmetric multioperators and ${\bf \large Q}\in {\mathcal B}^{(d)}({\mathcal H})$ is an $q$-nilpotent multioperators, then ${\bf\large R} +{\bf\large Q}$ is an $(m + 2q - 2,n+2q-1)$-isosymmetric multioperators under suitable conditions. Moreover, we give some results about the joint approximate spectrum of an $(m,n)$-isosymmetric multioperators.