CyberSec Research

We investigate existence and uniqueness of maximal plurisubharmonic functions on bounded domains with boundary data that are not assumed to be continuous or bounded. The result is applied to approximate (possibly unbounded from above) plurisubharmonic functions by continuous quasi upper bounded ones. A key step in our approach is to explore continuity of the Perron-Bremermann envelope of plurisubharmonic functions that are dominated by a given function $\phi$ defined on the closure of the domain.

In "Meromorphic Functions and Analytic Curves", H. and F. J. Weyl identified an intriguing connection between holomorphic curves and their associated curves, which they referred to as the "peculiar relation". In this paper, we present a generalization of the Weyl peculiar relation and investigate a combinatorial structure underlying the Weyl--Ahlfors theory via standard Young tableaux. We also provide an alternative proof of the Second Main Theorem from the viewpoint of comparing the order functions $iT_p$ and $T_i\{\mathbf{X}^{(p)}\}$.

We prove that for every $0 < c < 4$ and every $N \in \mathbb{N}$ there exists a monic polynomial $p(z) = z^n + a_{n-1} z^{n-1} + \dots + a_0$ such that the set $\{z \in \mathbb{C} : |p(z)| \leq 1\}$ has at least $N$ connected components with diameter at least $c$. This answers a question of Erd\H{o}s.

In this article, the authors survey and review the studies of boundary value problems for regular functions in Clifford analysis, which include theoretical foundations and useful methods. Its theoretical bases consist of the generalized Cauchy theorem, the generalized Cauchy integral formula, the Painlev\'{e} theorem and boundary behaviors of the Cauchy type integrals, as well as various integral representations. Certain boundary value problems in the Clifford algebra setting and singular integral equations are introduced.

We prove a Weyl-type theorem for the Kohn Laplacian on sphere quotients as CR manifolds. We show that we can determine the fundamental group from the spectrum of the Kohn Laplacian in dimension three. Furthermore, we prove Sobolev estimates for the complex Green's operator on these quotient manifolds.

We study the Dirichlet problem for the complex Monge-Amp\`ere equation on a strictly pseudo-convex domain in Cn or a Hermitian manifold. Under the condition that the right-hand side lies in Lp function and the boundary data are H\"older continuous, we prove the global H\"older continuity of the solution.

In this paper, the derivative tent space \(DT_p^q(\alpha)\) is introduced. Then, we study \(\mathcal{C}_{\mathcal{B}_{{\log}^\gamma}^\beta}(DT_p^q(\alpha)\cap\mathcal{B}_{{\log}^\gamma}^\beta)\), the closure of the derivative tent space \(DT_p^q(\alpha)\) in the logarithmic Bloch-type space \(\Blog\). As a byproduct, some new characterizations for \(C_\mathcal{B}(\mathcal{D}^p_{\alpha} \cap \mathcal{B})\) and \(C_{\mathcal{B}_{{\log}}}(\mathcal{D}^2_{\alpha}\cap\mathcal{B}_{{\log}})\) are obtained.

The purpose of this article is twofold. First, we prove that the squeezing function approaches 1 near strongly pseudoconvex boundary points of bounded domains in $\mathbb{C}^{n+1}$. Second, we show that the squeezing function approaches 1 along certain sequences converging to pseudoconvex boundary points of finite type, including uniformly $\Lambda$-tangential and spherically $\frac{1}{2m}$-tangential convergence patterns.

We apply the approach developed in our previous papers to obtain examples of solutions to the inverse spectral problem (ISP) for the canonical Hamiltonian system. One of our goals is to illustrate connections of ISP with classical tools of analysis, such as the Hilbert transform and solutions to the Riemann-Hilbert problem. A key role in our study is played by the systems with homogeneous and quasi-homogeneous spectral measures. We show how some of such systems give rise to families of Bessel functions.

This is the third article of a series of our recent works, addressing an open question of Bonk-Heinonen-Koskela [3], to study the relationship between (inner) uniformality and Gromov hyperbolicity in infinite dimensional spaces. Our main focus of this paper is to establish improved geometric characterization of Gromov hyperbolicity. More precisely, we develop an elementary measure-independent approach to establish the geometric characterization of Gromov hyperbolicity for general proper Euclidean subdomains, which addresses a conjecture of Bonk-Heinonen-Koskela [Asterisque 2001] for unbounded Euclidean subdomains. Our main results not only improve the corresponding result of Balogh-Buckley [Invent. Math. 2003], but also clean up the relationship between the two geometric conditions, ball separation condition and Gehring-Hayman inequality, that used to characterize Gromov hyperbolicity. We also provide a negative answer to an open problem of Balogh-Buckley by constructing an Euclidean domain with ball separation property but fails to satisfy the Gehring-Hayman inequality. Furthermore, we prove that ball separation condition, together with an LLC-2 condition, implies inner uniformality and thus the Gehring-Hayman inequality. As a consequence of our new approach, we are able to prove such a geometric characterization of Gromov hyperbolicity in the fairly general setting of metric spaces (without measures), which substantially improves the main result of Koskela-Lammi-Manojlovi\'c [Ann. Sci. \'Ec. Norm. Sup\'er. 2014]. In particular, we not only provide a new purely metric proof of the main reuslt of Balogh-Buckley and Koskela-Lammi-Manojlovi\'c, but also derive explicit dependence of various involved constants, which improves all the previous known results.

In the paper, we use the idea of normal family to find out the possible solution of the following special case of algebraic differential equation \[P_k\big(z,f,f^{(1)},\ldots, f^{(k)}\big)=f^{(1)}(f-\mathscr{L}_k(f))-\varphi (f-a)(f-b)=0,\] where $\mathscr{L}_k(f)=\sideset{}{_{i=0}^k}{\sum} a_i f^{(i)}$ and $\varphi$ is an entire function, $a_i\in\mathbb{C}\;(i=0,1,\ldots, k)$ such that $a_k=1$ and $a, b\in\mathbb{C}$ such that $a\neq b$. The obtained results improve and generalise the results of Li and Yang \cite{LY1} and Xu et al. \cite{XMD} in a large scale.

Let \( f \) be a transcendental entire function with hyper-order strictly less than 1. Under certain conditions, the difference analogues and delay-differential analogues of the Br\"uck conjecture are proved respectively by using Nevanlinna theory. As applications of these two results, the relationship between $f$ and $\Delta^n f$ (or between $f'$ and $f(z + 1)$) is established provided that $f$ and $\Delta^n f$ (or $f'$ and $f(z + 1)$) share a finite set. Moreover, some examples are provided to illustrate these results.

Agler and McCarthy studied the uniqueness of a 3-point interpolation problem in the bidisc. This note aims to solve an analogous problem in the unit Euclidean ball in an arbitrary dimension.

We first prove a Boundary Schwarz lemma for holomorphic disks on the unit ball in $\mathbb{C}^n$. Further by using a Schwarz lemma for minimal conformal disks of Forstneri\v c and Kalaj (F.~Forstneri{\v{c}} and D.~Kalaj. \newblock Schwarz-pick lemma for harmonic maps which are conformal at a point. \newblock {\em Anal. PDE}, 17(3):981--1003, 2024.) we prove the boundary Schwarz lemma for such minimal disks.

In this paper, we consider estimates of symmetric Toeplitz determinants $T_{q,n}(f)$ for the class ${\mathcal U}$ and for the general class ${\mathcal S}$ for certain values of $q$ and $n$ ($q,n=1,2,3\ldots$).

In this paper, the Hadamard-Bergman convolution and Banach algebra structure by the Duhamel product on Hardy-Carleson type tent spaces was investigated. Moreover, the boundedness and compactness of the Ces\`aro-like operator $\mathcal{C}_\mu$ on Hardy-Carleson type tent spaces $AT_p^\infty(\alpha)$ are also studied.

In this short note, we prove that on a compact K\"ahler variety $X$ with log terminal singularities and $c_1(X)=0$, any singular Ricci-flat K\"ahler metric has orbifold singularities in restriction to the orbifold locus of $X$.

This note provides a complete description of a family of sense preserving harmonic functions in the open unit disk that have the same Jacobians, provided that one of the representatives of this family is known.