Let $(X,0)$ be a reduced, equidimensional germ of an analytic singularity with reduced tangent cone $(C_{X,0},0)$. We prove that the absence of exceptional cones is a necessary and sufficient condition for the smooth part ${𝔛}^0$ of the specialization to the tangent cone $\varphi :𝔛\to ℂ$ to satisfy Whitney’s conditions along the parameter axis $Y$. This result is a first step in generalizing to higher dimensions Lê and Teissier’s result for hypersurfaces of ${ℂ}^3$ which establishes the Whitney equisingularity of $X$ and its tangent...

Let $(X,d,\mu )$ be a metric measure space endowed with a distance $d$ and a nonnegative Borel doubling measure $\mu$. Let $L$ be a non-negative self-adjoint operator of order $m$ on $L^2\left(X\right)$. Assume that the semigroup ${\mathrm{e}}^{-tL}$ generated by $L$ satisfies the Davies-Gaffney estimate of order $m$ and $L$ satisfies the Plancherel type estimate. Let $H_L^p\left(X\right)$ be the Hardy space associated with $L.$ We show the boundedness of Stein’s square function ${𝒢}_{\delta }\left(L\right)$ arising from Bochner-Riesz means associated to $L$ from Hardy spaces $H_L^p\left(X\right)$ to $L^p\left(X\right)$, and also study...

The objective of this manuscript is to investigate the structure of linear maps on the space of real symmetric matrices ${𝒮}^n$ that leave invariant the closed convex cones of copositive and completely positive matrices (${\mathrm{COP}}_n$ and ${\mathrm{CP}}_n$). A description of an invertible linear map on ${𝒮}^n$ such that $L\left({\mathrm{CP}}_n\right)\subset C{P}_n$ is obtained in terms of semipositive maps over the positive semidefinite cone ${𝒮}_{+}^n$ and the cone of symmetric nonnegative matrices ${𝒩}_{+}^n$ for $n\le 4$, with specific calculations for $n=2$. Preserver properties of the Lyapunov...

The aim of this paper is to introduce some new fixed point results of Hardy-Rogers-type for $\alpha$-$\eta$-$GF$-contraction in a complete metric space. We extend the concept of $F$-contraction into an $\alpha$-$\eta$-$GF$-contraction of Hardy-Rogers-type. An example has been constructed to demonstrate the novelty of our results.

We prove some optimal estimates of Hölder-logarithmic type in the Hardy-Sobolev spaces $H^{k,p}\left(G\right)$, where $k\in {\mathbb{N}}^{*}$, $1\le p\le \infty$ and $G$ is either the open unit disk $𝔻$ or the annular domain $G_s$, $0<s<1$ of the complex space $ℂ$. More precisely, we study the behavior on the interior of $G$ of any function $f$ belonging to the unit ball of the Hardy-Sobolev spaces $H^{k,p}\left(G\right)$ from its behavior on any open connected subset $I$ of the boundary $\partial G$ of $G$ with respect to the $L^1$-norm. Our results can be viewed as an improvement and generalization of...

AbstractThe paper contains studies of relationships between properties of the “translation” mappings $T_F$ and the topological and geometric structure of spaces X and Hardy classes $h^p(,X)$ of X-valued harmonic functions on the open unit disk in ℂ (X is a Banach space). The mapping $T_F$ transforming the unit circle of ℂ into $h^p(,X)$ is associated with a function $F\in h^p(,X)$ by the formula $T_F\left(t\right)=F\circ \varphi ₜ$, where ϕₜ is the rotation of through t.AcknowledgmentsThis work is based in part on the author’s doctoral thesis written at...

The main aim of this paper is to prove that the maximal operator ${\sigma }^{}$ is bounded from the Hardy space $H_{1/2}$ to weak-$L_{1/2}$ and is not bounded from $H_{1/2}$ to $L_{1/2}$.

Let A be a uniform algebra on X and σ a probability measure on X. We define the Hardy spaces $H^p\left(\sigma \right)$ and the $H^p\left(\sigma \right)$ interpolating sequences S in the p-spectrum ${ℳ}_p$ of σ. We prove, under some structural hypotheses on A and σ, that if S is a “dual bounded” Carleson sequence, then S is $H^s\left(\sigma \right)$-interpolating with a linear extension operator for s < p, provided that either p = ∞ or p ≤ 2. In the case of the unit ball of ℂⁿ we find, for instance, that if S is dual bounded in $H^{\infty }\left(\right)$ then S is $H^p\left(\right)$-interpolating with...

Given 0 < p,q < ∞ and any sequence z = zₙ in the unit disc , we define an operator from functions on to sequences by $T_{z,p}\left(f\right)={(1-|zₙ\left|²\right)}^{1/p}f\left(zₙ\right)$. Necessary and sufficient conditions on zₙ are given such that $T_{z,p}$ maps the Hardy space $H^p$ boundedly into the sequence space ${\ell }^q$. A corresponding result for Bergman spaces is also stated.

The main purpose of this article is to give a generalization of the logarithmic-type estimate in the Hardy-Sobolev spaces $H^{k,p}\left(G\right)$; $k\in {\mathbb{N}}^{*}$, $1\le p\le \infty$ and $G$ is the open unit disk or the annulus of the complex space $ℂ$.

Let $A_{\alpha }f\left(x\right)={\left|B\right(0,\left|x\right|\left)\right|}^{-\alpha /n}{\int }_{B(0,|x\left|\right)}f\left(t\right)dt$ be the n-dimensional fractional Hardy operator, where 0 < α ≤ n. It is well-known that $A_{\alpha }$ is bounded from $L^p$ to $L^{p_{\alpha }}$ with $p_{\alpha }=np/(\alpha p-np+n)$ when n(1-1/p) < α ≤ n. We improve this result within the framework of Banach function spaces, for instance, weighted Lebesgue spaces and Lorentz spaces. We in fact find a ’source’ space $S_{\alpha ,Y}$, which is strictly larger than X, and a ’target’ space $T_Y$, which is strictly smaller than Y, under the assumption that $A_{\alpha }$ is bounded from X into Y and the Hardy-Littlewood...

We consider functions $u\in W_0^{m,1}\left(\Omega \right)$, where $\Omega \subset {ℝ}^N$ is a smooth bounded domain, and $m\ge 2$ is an integer. For all $j\ge 0,1\le k\le m-1$, such that $1\le j+k\le m$, we prove that $\frac{{\partial }^{i}u\left(x\right)}{d{\left(x\right)}^{m-j-k}}\in W_0^{k,1}\left(\Omega \right)$ with $∥{\partial }^k{\left(\frac{{\partial }^{i}u\left(x\right)}{d{\left(x\right)}^{m-j-k}}\right)}_{L^1\left(\Omega \right)}\le C∥u∥{}_{W^{m,1}\left(\Omega \right)}$, where $d$ is a smooth positive function which coincides with dist$(x,\partial \Omega )$ near $\partial \Omega$, and ${\partial }^l$ denotes any partial differential operator of order $l$.

Let ${ℒ}_1=-\Delta +V$ be a Schrödinger operator and let ${ℒ}_2={(-\Delta )}^2+V^2$ be a Schrödinger type operator on ${ℝ}^n$ $(n\ge 5)$, where $V\ne 0$ is a nonnegative potential belonging to certain reverse Hölder class $B_s$ for $s\ge n/2$. The Hardy type space $H_{{ℒ}_2}^1$ is defined in terms of the maximal function with respect to the semigroup $\left\{{\mathrm{e}}^{-t{ℒ}_2}\right\}$ and it is identical to the Hardy space $H_{{ℒ}_1}^1$ established by Dziubański and Zienkiewicz. In this article, we prove the $L^p$-boundedness of the commutator ${ℛ}_b=bℛf-ℛ\left(bf\right)$ generated by the Riesz transform $ℛ={\nabla }^2{ℒ}_2^{-1/2}$, where $b\in {\mathrm{BMO}}_{\theta }\left(\rho \right)$, which is larger...

Let $L$ be a non-negative self-adjoint operator acting on $L^2\left({ℝ}^n\right)$ satisfying a pointwise Gaussian estimate for its heat kernel. Let $w$ be an $A_r$ weight on ${ℝ}^n\times {ℝ}^n$, $1<r<\infty$. In this article we obtain a weighted atomic decomposition for the weighted Hardy space $H_{L,w}^p({ℝ}^n\times {ℝ}^n)$, $0<p\le 1$ associated to $L$. Based on the atomic decomposition, we show the dual relationship between $H_{L,w}^1({ℝ}^n\times {ℝ}^n)$ and ${\mathrm{BMO}}_{L,w}({ℝ}^n\times {ℝ}^n)$.