Search arXiv⌕ Search
Home/Archive/arXiv

arXiv · 2503.16239

Generalized Double Operator Integrals: Finite Dimensions

Shih-Yu Chang
View original source ↗Read source document ↗Export metadata ↓

Abstract

The Double Operator Integral (DOI) framework provides a powerful tool for analyzing perturbations and interactions between self-adjoint operators in functional analysis and spectral theory. However, most existing DOI formulations rely on self-adjointness (Hermitian) or unitary assumptions, limiting their applicability to non-Hermitian settings. Motivated by advancements in non-Hermitian physics and operator theory, this paper introduces Generalized Double Operator Integrals (GDOIs), extending DOI theory to arbitrary non-Hermitian and non-normal matrices. We establish key algebraic properties of GDOIs, derive norm estimations, and develop a perturbation formula that leads to Lipschitz continuity estimates for operator functions. Additionally, we prove the continuity of GDOIs and explore applications in random matrix theory and functional analysis, including tail bounds and Hölder-type estimations. These results provide a unified and flexible integral framework for non-Hermitian spectral analysis, broadening the impact of DOI techniques in non-commutative analysis and mathematical physics.

Explore related subjects

math.FAmath.OA

Keep this discovery

Explore connections, maps & timelines

BibTeXRIS

Shih-Yu Chang. 2025-03-20. Generalized Double Operator Integrals: Finite Dimensions. https://arxiv.org/abs/2503.16239

Cite the original work for its findings. Save a collection to share your selection of sources.

KEEP EXPLORING

Related papers

arXiv2026

The Weyl-von Neumann theorem for antilinear skew-self-adjoint operators

In this article, we prove the Weyl--von Neumann theorem for bounded antilinear skew-self-adjoint operators. More specifically, we prove the following: Let $A$ be a bounded antilinear skew-self-adjoint operator on a separable Hilbert space $H$ whose kernel is either even dimensional or infinite dimensional. Let $1 0$ there exists an antilinear block skew-diagonal operator $D$ and an antilinear skew-self-adjoint Schatten $p$-class operator $K$ such that $A=K+D$ with $\|K\|_{p}<ε$. As a consequence, we prove the Weyl--von Neumann theorem for complex skew-symmetric operators: Let $τ$ be a conjugation on $H$ and let $T$ be a bounded linear operator $τ$-skew-symmetric with $\dim N(T)=\infty$ or $\dim N(T)$ is even. Let $1 0$, there exists a $τ$-skew-symmetric Schatten $p$-class operator $K$, a skew-symmetric block diagonal operator $D$ and a unitary operator $U$ such that $T=K+UDU^{tr}$ and $\|K\|_{p}<ε$, where $U^{tr}$ is the transpose of $U$ with respect to an orthonormal basis ${\{e_n:n\in \mathbb N}\}$ such that $τ(e_n)=e_n$ for each $n\in \mathbb N$. Furthermore, the above result holds even without any assumption on the dimension of $N(T)$, provided that $N(T)=N(T^*)$.

math.FA↗
arXiv2026

Schur bounded patterns, submajorisation and operator Lipschitz functions

A Schur bounded pattern is a subset $S\subset \mathbb{N}^2$ such that Schur multiplication by every bounded function on $\mathbb{N}^2$ supported on $S$ defines a bounded linear operator in the norm of $\mathcal{B}(\ell_2(\mathbb{N})).$ Schur bounded patterns were characterised by Davidson-Donsig as being unions of row-bounded and column-bounded sets. We study the analogous question for sets $S$ such that element-wise multiplication by every bounded function on $S$ is bounded in ideals of compact operators that are not closed under submajorisation, in particular the Schatten ideals $\mathcal{L}_p$ with $0<p<1$ and the weak Schatten ideal $\mathcal{L}_{1,\infty}.$ Conversely we characterise the ideals that are not closed under submajorisation by their Schur bounded patterns. This has implications for the functions which are Lipschitz in the norm of ideals that are not closed under submajorisation. In particular such functions must be differentiable and have derivative that is asymptotically constant at infinity.

math.FA↗
arXiv2026

Derivatives of Tensor Products and Applications to Spaces $C(K^n,X)$

In this paper, we develop an abstract theory of derivatives for Banach spaces based on objects that we call \emph{bidual assignments}. This framework encompasses both the Semadeni derivative and the recently introduced Semadeni--Pełczyński derivative. More generally, suitable ideals of subsets of dual spaces give rise to a broad family of derivatives within this setting. We establish direct-sum and tensor-product formulas for these derivatives, showing that they behave naturally with respect to direct sums and injective tensor products. We then obtain explicit descriptions of derivatives associated with compact trees and finite products of compact lines. In particular, we compute iterated derivatives and use them to derive isomorphic invariants for vector-valued spaces of continuous functions. As one consequence, if $K=\prod_{i=1}^n K_i$ and $L=\prod_{j=1}^m L_j$, where $n,m\geq1$ and all the factors are compact lines of uncountable character, then, for $1\leq p,q<\infty$, \[ C(K,\ell_p)\sim C(L,\ell_q) \] implies that $n=m$ and $p=q$. We also establish classification results for spaces of the form $C(K^n,X)$. In particular, for uncountable ordinals $α$ and $β$, an integer $n\geq1$, and Banach spaces $X$ satisfying suitable rigidity assumptions, we prove that \[ C([0,α]^n,X)\sim C([0,β]^n,X) \quad\text{if and only if}\quad C([0,α])\sim C([0,β]). \] This extends Kislyakov's classification of the spaces $C([0,α])$ and its vector-valued extension due to Galego to finite powers of ordinal intervals.

math.FA↗