M. S. Moslehian, J. S. Matharu, J. S. Aujla
We present an operator version of the Callebaut inequality involving the interpolation paths and apply it to the weighted operator geometric means. We also establish a matrix version of the Callebaut inequality and as a consequence obtain an inequality including the Hadamard product of matrices.
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The Callebaut inequality says that \begin{align*} \sum_{ j=1}^n \left(A_j\sharp B_j\right)\leq \left(\sum_{ j=1}^n A_j σB_j\right)\sharp\left(\sum_{ j=1}^n A_j σ^{\bot} B_j\right)\leq\left(\sum_{ j=1}^n A_j\right)\sharp \left(\sum_{ j=1}^nB_j\right)\,, \end{align*} where $A_j, B_j\,\,(1\leq j\leq n)$ are positive invertible operators and $σ$ and $σ^\perp$ are an operator mean and its dual in the sense of Kabo and Ando, respectively. In this paper we employ the Mond--Pečarić method as well as some operator techniques to establish a complementary inequality to the above one under mild conditions…
In this paper we consider non-commutative analogue for the arithmeticgeometric mean inequality $$a^{r}b^{1-r}+(r-1)b\geq ra$$ for two positive numbers $a,b$ and $r> 1$. We show that under some assumptions the non-commutative analogue for $a^{r}b^{1-r}$ which satisfies this inequality is unique and equal to $r$-mean. The case $0<r<1$ is also considered. In particular, we give a new characterization of the geometric mean.
We give an alternate proof of one of the inequalities proved recently for martingales (=sums of martingale differences) in a non-commutative $L_p$-space, with $1<p<\infty$, by Q. Xu and the author. This new approach is restricted to $p$ an even integer, but it yields a constant which is $O(p)$ when $p\to \infty$ and it applies to a much more general kind of sums which we call $p$-orthogonal.
In this paper, we extend the classical Bohr's inequality to the setting of the non-commutative Hardy space $H^1$ associated with a semifinite von Neumann algebra. As a consequence, we obtain Bohr's inequality for operators in the von Neumann-Schatten class $\cl C_1$ and square matrices of any finite order. Interestingly, we establish that the optimal bound for $r$ in the above mentioned Bohr's inequality concerning von Neumann-Shcatten class is 1/3 whereas it is 1/2 in the case of $2\times 2$ matrices and reduces to $\sqrt{2}-1$ for the case of $3\times 3$ matrices. We also obtain a generaliza…
The non-commutative Stein inequality asks whether there exists a constant $C_{p,q}$ depending only on $p, q$ such that \begin{equation*} \left\| \left(\sum_{n} |\mathcal{E}_{n} (x_n) |^{q}\right)^{\frac{1}{q}} \right\|_p \leq C_{p,q} \left\| \left(\sum_{n} | x_n |^q \right)^{\frac{1}{q}}\right \|_p\qquad \qquad (S_{p,q}), \end{equation*} for (positive) sequences $(x_n)$ in $L_p(\mathcal{M})$. The validity of $(S_{p,2})$ for $1 < p < \infty$ and $(S_{p,1})$ for $1 \leq p < \infty$ are known. In this paper, we verify (i) $(S_{p,\infty})$ for $1 < p \leq \infty$; (ii) $(S_{p,p})$ for $1 \leq p < …
We prove a weak-type (1,1) inequality for square functions of non-commutative martingales that are simultaneously bounded in $L^2$ and $L^1$. More precisely, the following non-commutative analogue of a classical result of Burkholder holds: there exists an absolute constant $K>0$ such that if $\cal{M}$ is a semi-finite von Neumann algebra and $(\cal{M}_n)^{\infty}_{n=1}$ is an increasing filtration of von Neumann subalgebras of $\cal{M}$ then for any given martingale $x=(x_n)^{\infty}_{n=1}$ that is bounded in $L^2(\cal{M})\cap L^1(\cal{M})$, adapted to $(\cal{M}_n)^{\infty}_{n=1}$, there exist…
We prove a Julia inequality for bounded non-commutative functions on polynomial polyhedra. We use this to deduce a Julia inequality for holomorphic functions on classical domains in $\mathbb{C}^d$. We look at differentiability at a boundary point for functions that have a certain regularity there.
We show that the validity of the non-commutative Khintchine inequality for some $q$ with $1<q<2$ implies its validity (with another constant) for all $1\le p<q$. We prove this for the inequality involving the Rademacher functions, but also for more general "lacunary" sequences, or even non-commutative analogues of the Rademacher functions. For instance, we may apply it to the "Z(2)-sequences" previously considered by Harcharras. The result appears to be new in that case. It implies that the space $\ell^n_1$ contains (as an operator space) a large subspace uniformly isomorphic (as an operator s…
We give a proof of the Khintchine inequalities in non-commutative $L_p$-spaces for all $0< p<1$. These new inequalities are valid for the Rademacher functions or Gaussian random variables, but also for more general sequences, e.g. for the analogues of such random variables in free probability. We also prove a factorization for operators from a Hilbert space to a non commutative $L_p$-space, which is new for $0<p<1$. We end by showing that Mazur maps are Hölder on semifinite von Neumann algebras. The main tool is a new form of Hölder inequality for non commutative Lp spaces with weights.
A Le Page--Kaplansky theorem characterizing commutative JB*-triples
本文证明了在度量上刻画可交换JB*-三元组的Le Page不等式成立，建立了可交换性与特定范数不等式等价性的结论。
We introduce the non-commutative $f$-divergence functional $Θ(\widetilde{A},\widetilde{B}):=\int_TB_t^{\frac{1}{2}}f\left(B_t^{-\frac{1}{2}} A_tB_t^{-\frac{1}{2}}\right)B_t^{\frac{1}{2}}dμ(t)$ for an operator convex function $f$, where $\widetilde{A}=(A_t)_{t\in T}$ and $\widetilde{B}=(B_t)_{t\in T}$ are continuous fields of Hilbert space operators and study its properties. We establish some relations between the perspective of an operator convex function $f$ and the non-commutative $f$-divergence functional. In particular, an operator extension of Csiszár's result regarding $f$-divergence fun…
We will show that if $\sM$ is a factor, then for any pair $\f, \p\in\sMdsup$ of normal positive linear functionals on $\sM$, the inequality: $$ \lrnorm{\f}\leq \lrnorm{\p} $$ is equivalent to the fact that there exist a countable family $\lrbrace{\ffdi: i\in I}\subset \sMdsup$ in $\sMdsup$ and a family $\lrbrace{\udi: i\in I}ı\sM$ of partial isometries in \cM such that $$ \f=\sumd{i\in I} \ffdi,\quad \sumd{i\in I} \udi{\ffdi}\udius\leq \p, \quad \text{and} \quad \udius\udi=s\lr{\ffdi}, i\in I, $$ where $s(ω), ω\in\sMdsup$, means the support projection of $ω$. Furthermore, if $\lrnorm{\f}=\lrno…
Some points of view on Grothendieck's inequalities
本文基于 Haagerup 的非交换小 Grothendieck 不等式证明，利用完全有界映射理论揭示交换 Grothendieck 不等式与小不等式的几何联系，并刻画复情形的小常数。
We give a method to obtain, from Voiculescu's inequality, norm estimates for sums of free variables with amalgamation in general fully symmetric spaces. We use these estimates to interpolate the Burkholder inequalities for non commutative martingales. The method is also applicable to other similar settings. In that spirit, we improve known results on the non commutative Johnson-Schechtman inequalities and recover Khintchine inequalities associated to free groups.
The main purpose of this paper is to prove Hörmander's $L^p$-$L^q$ boundedness of Fourier multipliers on commutative hypergroups. We carry out this objective by establishing Paley inequality and Hausdorff-Young-Paley inequality for commutative hypergroups. We show the $L^p$-$L^q$ boundedness of the spectral multipliers for the generalised radial Laplacian by examining our results on Chébli-Trimèche hypergroups. As a consequence, we obtain embedding theorems and time asymptotics for the $L^p$-$L^q$ norms of the heat kernel for generalised radial Laplacian. Finally, we present applications of th…
Weighted weak $(1,1)$ estimate for non-commutative square function
该研究在非交换框架下探讨与球平均差分、鞅关联的平方函数的加权弱(1,1)不等式，拓展了已有非交换平方函数估计结果的加权情形。
Finite Riesz products and Ornstein non-inequalities on quantum tori
本文研究了量子环上有限里斯茨积的构造，并基于此推导出非交换奥本海姆非等式。
In information theory, the well-known log-sum inequality is a fundamental tool which indicates the non-negativity for the relative entropy. In this article, we establish a set of inequalities which are similar to the log-sum inequality involving two functions defined on scalars. The parametric extended log-sum inequalities are shown. We extend these inequalities for the commutative matrices. In addition, utilizing the Löwner partial order relation and the Hansen-Pedersen theory for non-commutative positive semi-definite matrices we demonstrate a number of matrix-inequalities analogous to the l…
It has been shown in "On the Hausdorff-Young theorem for commutative hypergroups" by Sina Degenfeld-Schonburg, that one can extend the domain of Fourier transform of a commutative hypergroup $K$ to $L^p(K)$ for $1\leq p \leq 2$, and the Hausdorff-Young inequality holds true for these cases. In this article, we examine the structure of non-zero functions in $L^p(K)$ for which equality is attained in the Hausdorff-Young inequality, for $1<p<2$, and further provide a characterization for the basic uncertainty principle for commutative hypergroups with non-trivial centre.
Non-commutative Law of iterated logarithm
本文证明了鞅和独立随机变量序列的经典迭代对数律的最优非交换类比，通过改进的指数不等式导出非交换Stout型LIL，并由此得到非交换Hartman-Wintner型LIL。
In this paper, we introduce a non-commutative space of stochastic distributions, which contains the non-commutative white noise space, and forms, together with a natural multiplication, a topological algebra. A special inequality which holds in this space allows to characterize its invertible elements and to develop an appropriate framework of non-commutative stochastic linear systems.
In this work, an operator superquadratic function (in operator sense) for positive Hilbert space operators is defined. Several examples with some important properties together with some observations which are related to the operator convexity are pointed out. Equivalent statements of a non-commutative version of Jensen's inequality for operator superquadratic function are established. A generalization of the main result to any positive unital linear map is also provided.
In this work, a pre-Grüss inequality for positive Hilbert space operators is proved. So that, some numerical radius inequalities are proved. On the other hand, based on a non-commutative Binomial formula, a non-commutative upper bound for the numerical radius of the summand of two bounded linear Hilbert space operators is proved. A commutative version is also obtained as well.
We formulate a non-commutative analog of the Brascamp-Lieb inequality, and prove it in several concrete settings.
We give a counterexample to a trilinear version of the operator space Grothendieck theorem. In particular, we show that for trilinear forms on $\ell_\infty$, the ratio of the symmetrized completely bounded norm and the jointly completely bounded norm is in general unbounded, answering a question of Pisier. The proof is based on a non-commutative version of the generalized von Neumann inequality from additive combinatorics.
Let A and B be two commutative semisimple Frechet algebras. We first give a characterization of the multiplier algebra of the direct sum of A and B. We then prove that A \oplus B is a BSE-algebra if and only if A and B are BSE-algebras. Furthermore, for a closed ideal I of A, we study multipliers of ideals and quotient algebras of A and show that I and A/I are BSE-algebras, under certain conditions.
Carbery's inequality in the Schatten--von Neumann classes
本文完全解决了非交换背景下 Carbery 关于 Schatten--von Neumann 类中算子族尖锐三角不等式的问题，对所有 p≥2 证明了最优不等式。
Let $\mathcal{M}$ be a semifinite von Neumann algebra. We equip the associated noncommutative $L_p$-spaces with their natural operator space structure introduced by Pisier via complex interpolation. On the other hand, for $1<p<\infty$ let $$L_{p,p}(\mathcal{M})=\big(L_{\infty}(\mathcal{M}),\,L_{1}(\mathcal{M})\big)_{\frac1p,\,p}$$ be equipped with the operator space structure via real interpolation as defined by the second named author ({\em J. Funct. Anal}. 139 (1996), 500--539). We show that $L_{p,p}(\mathcal{M})=L_{p}(\mathcal{M})$ completely isomorphically if and only if $\mathcal{M}$ is f…
The main purpose of this paper is to study the validity of the Hausdorff-Young inequality for vector-valued functions defined on a non-commutative compact group. The natural context for this research is that of operator spaces. This leads us to formulate a whole new theory of Fourier type and cotype for the category of operator spaces. The present paper is the first step in this program, where the basic theory is presented, the main examples are analyzed and some questions are posed.
Cyclicity of stable matrix free polynomials over non-commutative operator unit balls
研究非交换算子单位球上矩阵自由多项式的循环性，通过稳定性和弱*拓扑特性，结合实化理论，探讨稳定非交换有理函数的循环性及非交换自由 Hardy 空间中结果的恢复。
Dynamic Nevanlinna-Pick Theory, Covariance Dilations, and Non-commutative Varieties
该研究推广了Nevanlinna-Pick插值理论，建立了相关算子理论框架，证明了H^∞(𝔻)成员关系的普遍检测方法，并揭示非交换内簇上Arveson型完全谱集表示失效的特性。
Talagrand-type transport inequalities for path spaces over Carnot groups
研究Carnot群上布朗运动的Talagrand型运输不等式，通过增强路径空间证明并探讨非交换态空间下的新现象。
We study non-linear traces of Choquet type and Sugeno type on the algebra of compact operators. They have certain partial additivities. We show that these partial additivities characterize non-linear traces of both Choquet type and Sugeno type respectively. There exists a close relation between non-linear traces of Choquet type and majorization theory. We study trace class operators for non-linear traces of Choquet type. More generally we discuss Schatten-von Neumann $p$-class operators for non-linear traces of Choquet type. We determine when they form Banach spaces. This is an attempt of non-…
Frame expansions with erasures: an approach through the non-commutative operator theory
本文证明任意n维框架在随机系数丢失下，可从(n log n)个随机系数高概率线性重建信源，优于正交基，证明基于非交换算子理论。
A reverse Riesz estimate combined with a spectral gap implies a Poincaré inequality
研究在巴拿赫空间中，由阿贝尔遍历扇形算子\(A\)及无界算子\(\partial\)构成的系统，通过反向里斯估计与谱隙条件，推出庞加莱不等式及伴随散度不等式，该方法统一且灵活，能恢复并扩展相关定理，适用于多种几何情形。
Let $\Cl$ denote the Clifford algebra over $\R^n$, which is the von Neumann algebra generated by $n$ self-adjoint operators $Q_j$, $j=1,...,n$ satisfying the canonical anticommutation relations, $Q_iQ_j+Q_jQ_i = 2δ_{ij}I$, and let $τ$ denote the normalized trace on $\Cl$. This algebra arises in quantum mechanics as the algebra of observables generated by $n$ Fermionic degrees of freedom. Let $\Dens$ denote the set of all positive operators $ρ\in\Cl$ such that $τ(ρ) =1$; these are the non-commutative analogs of probability densities in the non-commutative probability space $(\Cl,τ)$. The Fermio…
The class of Schur-Agler functions over a domain ${\mathcal D} \subset {\mathbb C}^{d}$ is defined as the class of holomorphic operator-valued functions on ${\mathcal D}$ for which a certain von Neumann inequality is satisfied when a commuting tuple of operators satisfying a certain polynomial norm inequality is plugged in for the variables. Such functions are alternatively characterized as those having a linear-fractional presentation which identifies them as transfer functions of a certain type of conservative structured multidimensional linear system. There now has been introduced a noncomm…
Noncommutative Bohnenblust--Hille Inequality for qudit systems
本文将非交换Bohnenblust–Hille不等式从qubit系统推广到任意局部维度的qudit系统，在Gell-Mann与Heisenberg–Weyl基下建立结果，并应用于量子可观测量学习。
On Isometric Embeddability of $S_q^m$ into $S_p^n$ as non-commutative Quasi-Banach space
本文研究拟-Banach范围内交换与非交换Schatten空间的等距嵌入，利用非交换Clarkson不等式等工具证明多类 $S_q^m$ 到 $S_p^n$ 的嵌入不存在。
Probably the most famous of Grothendieck's contributions to Banach space theory is the result that he himself described as "the fundamental theorem in the metric theory of tensor products". That is now commonly referred to as "Grothendieck's theorem" (GT in short), or sometimes as "Grothendieck's inequality". This had a major impact first in Banach space theory (roughly after 1968), then, later on, in $C^*$-algebra theory, (roughly after 1978). More recently, in this millennium, a new version of GT has been successfully developed in the framework of "operator spaces" or non-commutative Banach …
The structure of non-commutative multiple correlation sequences and applications
该研究刻画了非交换二重多重相关序列的结构，分析其正性性质，推广Chu不等式得到量化形式，并应用于线性形式乘积的多重 recurrence 定理及二次方程的分划正则性结果，推广了Frantzikinakis与Host的定理。
We generalize the concepts of weak quantum logarithmic Sobolev inequality (LSI) and weak hypercontractivity (HC), introduced in the quantum setting by Olkiewicz and Zegarlinski, to the case of non-primitive quantum Markov semigroups (QMS). The originality of this work resides in that this new notion of hypercontractivity is given in terms of the so-called amalgamated $\mathbb{L}_p$ norms introduced recently by Junge and Parcet in the context of operator spaces theory. We make three main contributions. The first one is a version of Gross' integration lemma: we prove that (weak) HC implies (weak…
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