arXiv subjects

Houkun Zhang

Publications and source records attributed to Houkun Zhang.

5 recordsLinked to original sources

arXiv2025

Heat kernel estimates, fractional Riesz transforms and applications on exterior domains

In this paper, we derive sharp two side heat kernel estimate on exterior $C^{1,1}$ domains in the plane, and sharp upper heat kernel bound on exterior $C^{1,\mathrm{Dini}}$ domains in $\mathbb{R}^n$, $n\ge 2$. Estimates for Green's function and Riesz potentials on exterior domains in the plane are also presented. Based on the heat kernel estimates, we show the boundedness of the fractional Riesz transforms on exterior $C^{1,\mathrm{Dini}}$ domains in $\mathbb{R}^n$, $n\ge 2$. Some further applications to product and chain rules and nonlinear Schrödinger equation are also presented.

math.CA↗

arXiv2022

The Köthe dual of mixed Morrey spaces and applications

In this paper, we study the separable and weak convergence of mixed-norm Lebesgue spaces. Furthermore, we prove that the block space $\mathcal{B}_{\vec{p}\,'}^{p'_0}(\mathbb{R}^n)$ is the Köthe dual of the mixed Morrey space $\mathcal{M}_{\vec{p}}^{p_0}(\mathbb{R}^n)$ by the Fatou property of these block spaces. The boundedness of the Hardy--Littlewood maximal function is further obtained on the block space $\mathcal{B}_{\vec{p}\,'}^{p'_0}(\mathbb{R}^n)$. As applications, the characterizations of $BMO(\mathbb{R}^n)$ via the commutators of the fractional integral operator $I_α$ on mixed Morrey spaces are proved as well as the block space $\mathcal{B}_{\vec{p}\,'}^{p'_0}(\mathbb{R}^n)$.

math.FA↗

arXiv2021

Mixed-norm Amalgam Spaces

We introduce the mixed-norm amalgam spaces $(L^{\vec{p}},L^{\vec{s}})(\mathbb{R}^n)$ and $(L^{\vec{p}},L^{\vec{s}})^α(\mathbb{R}^n)$, and show their some basic properties. In addition, we find the predual $\mathcal{H}(\vec{p}',\vec{s}\,',α')$ of mixed-norm amalgam spaces $(L^{\vec{p}},\ell^{\vec{s}})^α(\mathbb{R}^n)$ by the dual spaces $(L^{\vec{p}'},\ell^{\vec{s}\,'})(\mathbb{R}^n)$ of $(L^{\vec{p}},\ell^{\vec{s}})(\mathbb{R}^n)$, where $(L^{\vec{p}},L^{\vec{s}})(\mathbb{R}^n)=(L^{\vec{p}},\ell^{\vec{s}})(\mathbb{R}^n)$ and $(L^{\vec{p}},L^{\vec{s}})^α(\mathbb{R}^n)=(L^{\vec{p}},\ell^{\vec{s}})^α(\mathbb{R}^n)$. Then, we study the strong-type estimates for fractional integral operators $I_γ$ on mixed-norm amalgam spaces $(L^{\vec{p}},L^{\vec{s}})^α(\mathbb{R}^n)$. And, the strong-type estimates of linear commutators $[b,I_γ]$ generated by $b\in BMO(\mathbb{R}^n)$ and $I_γ$ on mixed-norm amalgam spaces $(L^{\vec{p}},L^{\vec{s}})^α(\mathbb{R}^n)$ are established as well. Furthermore, based on the dual theorem, the characterization of $BMO(\mathbb{R}^n)$ by the boundedness of $[b,I_γ]$ from $(L^{\vec{p}},L^{\vec{s}})^α(\mathbb{R}^n)$ to $(L^{\vec{q}},L^{\vec{s}})^β(\mathbb{R}^n)$ is given, which is a new result even for the classical amalgam spaces.

math.FA↗

arXiv2021

The Boundedness of Fractional Integral Operators in Local and Global Mixed Morrey-type Spaces

In this paper, we introduced the local and global mixed Morrey-type spaces, and some properties of these spaces are also studied. After that, the necessary conditions of the boundedness of fractional integral operators $I_α$ are studied respectively in mixed-norm Lebesgue spaces and the local mixed Morrey-type spaces. Last but not least, the boundedness of $I_α$ is obtained by Hardy operators' boundedness in weighted Lebesgue spaces. As corollaries, we acquire the boundedness of $I_α$ in mixed Morrey spaces(\hyperlink{Corollary 5.6}{Corollary 5.6}) and mixed Lebesgue spaces(\hyperlink{Corollary 5.7}{Corollary 5.7}) respectively. Particularly, \hyperlink{Corollary 5.7}{Corollary 5.7} obtains a sufficient and necessary condition.

math.FA↗

arXiv2021

Necessary and sufficient conditions for boundedness of commutators of fractional integral operators on mixed-norm Lebesgue spaces

In this paper, the sharp maximal theorem is generalized to mixed-norm ball Banach function spaces, which is defined as Definition 2.7. As an application, we give a characterization of BMO via the boundedness of commutators of fractional integral operators on mixed-norm Lebesgue spaces. Moreover, the characterization of homogeneous Lipschitz space is also given by the boundedness of commutators of fractional integral operators on mixed-norm Lebesgue spaces. Finally, two applications of Corollary 6.4 are given.

math.FA↗