arXiv subjects
Publications and source records attributed to Bo-Yong Chen.
In this article, we investigate the (big) Hankel operators $H_f$ on Hardy spaces of strongly pseudoconvex domains with smooth boundaries in $\mathbb{C}^n$. We also give a necessary and sufficient condition for boundedness of the Hankel operator $H_f$ on the Hardy space of the unit disc, which is new in the setting of one variable.
Let $M$ be a closed complex submanifold in ${\mathbb C}^N$ with the complete Kähler metric induced by the Euclidean metric. Several finiteness theorems on the $L^p$ Bergman space of holomorphic sections of a given Hermitian line bundle $L$ over $M$ and the associated $L^2$ cohomology groups are obtained. Some infiniteness theorems are also given in order to test the accuracy of finiteness theorems. As applications we obtain some rigidity results concerning growth of curvatures.
We prove a sharp $L^p$ weighted Hardy inequality involving boundary distance $δ$ for any domain $Ω\subsetneq \mathbb R^n$. The inequality may be improved substantially under the additional assumption that $-\log δ$ is subharmonic. Applications of these inequalities to the principle frequency of the $p-$Laplacian are given.
Based on Harnack's inequality and convex analysis we show that each plurisubharmonic function is locally BUO (bounded upper oscillation) with respect to polydiscs of finite type but not for arbitrary polydiscs. We also show that each function in the Lelong class is globally BUO with respect to all polydiscs. A dimension-free BUO estimate is obtained for the logarithm of the modulus of a complex polynomial. As an application we obtain an approximation formula for the Bergman kernel that preserves all directional Lelong numbers. For smooth plurisubharmonic functions we derive a new asymptotic identity for the Bergman kernel from Berndtsson's complex Brunn--Minkowski theory, which also yields a slightly better version of the sharp Ohsawa--Takegoshi extension theorem in some special cases.
Let $ψ$ be a plurisubharmonic function on the closed unit ball and $K_{tψ}(z)$ the Bergman kernel on the unit ball with respect to the weight $tψ$. We show that the boundary behavior of $K_{tψ}(z)$ is determined by certain directional Lelong number of $ψ$ for all $t$ smaller than the John-Nirenberg exponent of $ψ$ associated to certain family of nonisotropic balls, which is always positive.
This paper is devoted to various applications of Hardy-Sobolev type inequalities. We derive a new $L^2$ estimate for the $\bar{\partial}-$equation on ${\mathbb C}^n$ which yields a quantitative generalization of the Hartogs extension theorem to the case when the singularity set is not necessary compact. We show that for any negative subharmonic function $ψ$ on ${\mathbb R}^n$, $n>2$, the BMO norm of $\log |ψ|$ is bounded above by $2\sqrt{n-2}$ and $|ψ|^γ$ satisfies a reverse Hölder inequality for every $0<γ<1$. We also show that every plurisubharmonic function is locally BMO. Several Liouville theorems for subharmonic functions on complete Riemannian manifolds are given. As a consequence, we get a Margulis type theorem that if a bounded domain in ${\mathbb C}^n$ covers a Zariski open set in a projective algebraic variety, then the group of deck transformations of the covering has trivial center.
Let $Ω\subset {\mathbb C}^n$ be a bounded domain with the hyperconvexity index $α(Ω)>0$. Let $\varrho$ be the relative extremal function of a fixed closed ball in $Ω$ and set $μ:=|\varrho|(1+|\log|\varrho||)^{-1}$, $ν:=|\varrho|(1+|\log|\varrho||)^n$. We obtain the following estimates for the Bergman kernel: (1) For every $0<α<α(Ω)$ and $2\le p<2+\frac{2α(Ω)}{2n-α(Ω)}$, there exists a constant $C>0$ such that $\int_Ω|\frac{K_Ω(\cdot,w)}{\sqrt{K_Ω(w)}}|^{p}\le C |μ(w)|^{-\frac{(p-2) n}α}$ for all $w\in Ω$. (2) For every $0 0$ such that $ \frac{|K_Ω(z,w)|^2}{K_Ω(z)K_Ω(w)}\le C (\min\{\frac{ν(z)}{μ(w)},\frac{ν(w)}{μ(z)}\})^r $ for all $z,w\in Ω$. Various application of these estimates are given.
We introduce a trick of dealing with $L^2$ estimates of $\bar{\partial}$ with singular weights on complete Kähler domains.
Let $\{Ω_t:-1<t<1\}$ be a family of bounded pseudoconvex domains and $φ_t\in PSH(Ω_t)$. Let $K_t(z,w)$ denote the Bergman kernel with weight $φ_t$ on $Ω_t$. We study the continuity and Hölder continuity of $K_t(z,w)$ in $t$. Several applications to singularity theory of psh functions are given, including a new proof of the openness theorem.
Let $\{M_j\}$ be a sequence of complete Riemannian surfaces which converges in the sense of Cheeger-Gromov to a complete Riemannian surface $M$. We study the convergence of the Bergman kernel $K_{M_j}$ of $M_j$ by using isoperimetric inequalities.
We prove a Thullen type extension theorem of plurisubharmonic functions across a closed complete pluripolar set, which generalizes a theorem of Siu. Our approach depends on an Ohsawa-Takegoshi type extension theorem for a single point in a bounded complete Kähler domain, which is of independent interest.
We show that each pseudoconvex domain $Ω\subset {\mathbb C}^n$ admits a holomorphic map $F$ to ${\mathbb C}^m$ with $|F|\le C_1 e^{C_2 \hatδ^{-6}}$, where $\hatδ$ is the minimum of the boundary distance and $(1+|z|^2)^{-1/2}$, such that every boundary point is a Casorati-Weierstrass point of $F$. Based on this fact, we introduce a new anti-hyperbolic concept --- universal dominability. We also show that for each $α>6$ and each pseudoconvex domain $Ω\subset {\mathbb C}^n$, there is a holomorphic function $f$ on $Ω$ with $|f|\le C_αe^{C_α' \hatδ^{-α}}$, such that every boundary point is a Picard point of $F$. Applications to the construction of holomorphic maps of a given domain onto some ${\mathbb C}^m$ are given.
We observe that the twisted Morrey-Kohn-Hörmander formula can be deduced directly from the Morrey-Kohn-Hörmander formula.
We give a Hörmander type $L^2-$estimate for the $\bar{\partial}-$equation with respect to the measure $δ_Ω^{-α}dV$, $α<1$, on any bounded pseudoconvex domain with $C^2-$boundary. Several applications to the function theory of weighed Bergman spaces $A^2_α(Ω)$ are given, including a corona type theorem, a Gleason type theorem, together with a density theorem. We investigate in particular the boundary behavior of functions in $A^2_α(Ω)$ by proving an analogue of the Levi problem for $A^2_α(Ω)$ and giving an optimal Gehring type estimate for functions in $A^2_α(Ω)$. A vanishing theorem for $A^2_1(Ω)$ is established for arbitrary bounded domains. Relations between the weighted Bergman kernel and the Szegö kernel are also discussed.
We obtain several results about stability of the Bergman kernel on a tower of coverings on complex manifolds. An effective version of Rhodes' result is given for a tower of coverings on a compact Riemann surface of genus greater than or equal to 2. Stability of the Bergman kernel is established for towers of coverings on hyperbolic Riemann surfaces and on complete Kaehler manifolds satisfying certain potential conditions. As a consequence, stability of the Bergman kernel is established for any tower of coverings of Riemann surfaces when the top manifold is simply-connected.
We give a direct proof of the Ohsawa-Takegoshi by solving directly the d-bar equation.
We give a precise estimate of the Bergman kernel for the model domain defined by $Ω_F=\{(z,w)\in \mathbb{C}^{n+1}:{\rm Im}w-|F(z)|^2>0\},$ where $F=(f_1,...,f_m)$ is a holomorphic map from $\mathbb{C}^n$ to $\mathbb{C}^m$, in terms of the complex singularity exponent of $F$.
We give sufficient conditions for the quotient of a free, properly discontinuous action on a bounded domain of holomorphy to be a Stein manifold in terms of Poincaré series or limit sets for orbits. An immediate consequence is that the quotient of any cyclic, free, properly discontinuous action on the unit ball or the bidisc is Stein.