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1999年3月,第一作者(Binder)提出了一个问题是证明对于任何Green映射$T:H\rightarrow\tilde \Omega$存在一个“良好方向”$\psi\in [0,2]$,即\begin{equation}\label{binder} \int\limits_0\limits^{1} |T''(re^{i\pi\psi})|dr <\infty, \quad\text{ for at least one } \quad \psi\in [0,2]. \end{equation}目前即使在$\partial \Omega $是实直线上的一个均匀完美子集的特殊情况下,这个问题仍然未解决。 在本文中,当$\Omega = \overline{C} \setminus E_0$时我们得到了一个正解,其中$E_0 \subset R $是一个扩张二次多项式的Julia集。
In March 1999, the first named author (Binder) posed the problem of showing that a ``good direction'' $\psi\in [0,2]$ exists, for any Green's mapping $T:H\rightarrow\tilde \Omega$, i.e., \begin{equation}\label{binder} \int\limits_0\limits^{1} |T''(re^{i\pi\psi})|dr <\infty, \quad\text{ for at least one } \quad \psi\in [0,2]. \end{equation} Presently this problem is open even in the special case where $\partial \Omega $ is a uniformly perfect subset of the real line. In this paper we obtain a positive solution when $\Omega = \overline{C} \setminus E_0$ where $E_0 \subset R $ is the Julia set of an expanding quadratic polynomial.
给定一个有界开子集$\Omega$和闭子集$A,B$of$\mathbb{R}^k$,我们讨论当一个估计$u(x)\le g(dist(x,A\cup B))$,$x\in\Omega\setminus(A\cup B)$对于在$\Omega\setminus B$上次调和的函数$u$时,意味着$u(x)\le h(dist(x,B))$,$x\in\Omega\setminus B$,其中$g,h:(0,\infty)\to (0,\infty)$是递减函数且$g(0^+)=h(0^+)=\infty$。 我们寻求$h$的显式表达式,以$g$表示。 我们给出了一些此类结果,并表明 Domar 的工作(On the existence of a largest subharmonic minorant of a given function, Ark. Mat., 3 (1957), pp. 429-440)允许由此推导出此方向的其他结果。 然后我们比较这两种方法。 对于解析函数的估计也得到了类似的结果。
Given a bounded open subset $\Omega$ and closed subsets $A,B$ of $\mathbb{R}^k$, we discuss when an estimate $u(x)\le g(dist(x,A\cup B))$, $x\in\Omega\setminus(A\cup B)$, for a function $u$ subharmonic on $\Omega\setminus B$, implies that $u(x)\le h(dist(x,B))$, $x\in\Omega\setminus B$, where $g,h:(0,\infty)\to (0,\infty)$ are decreasing functions and $g(0^+)=h(0^+)=\infty$. We seek for explicit expressions of $h$ in terms of $g$. We give some results of this type and show that Domar's work (On the existence of a largest subharmonic minorant of a given function, Ark. Mat., 3 (1957), pp. 429-440) permits one to deduce other results in this direction. Then we compare these two approaches. Similar results are deduced for estimates of analytic functions.
我们考虑将经典的Chebotarev问题扩展到更高亏格的黎曼曲面,旨在推动代数曲线上的Padé逼近理论的发展。 为此,我们定义了一个适当的容量概念,模仿标准的容量,这是基于Chirka以及作者和合作者的研究成果。 黎曼曲面的非平凡拓扑要求进一步明确解中“同伦类”的连续体。 我们还讨论了这个问题与Jenkins-Strebel二次微分理论之间的关系。
We consider the extension to higher genus Riemann surfaces of the classical Chebotarev problem, with a view towards the development of the theory of Pad\'e\ approximants on algebraic curves. To this end we define an appropriate notion of capacity that mimics the standard one, following works of Chirka and of the author and collaborators. The nontrivial topology of the Riemann surface requires further specification of the ``homotopy class'' of the continua in the solution of the Chebotarev problem. We also discuss the relationship of this problem to the theory of Jenkins-Strebel quadratic differentials.
1995年,Kollár猜想,一个光滑复射影$n$-流形$X$,其一般情况下基本群很大,则欧拉示性数为$\chi(X, K_X)\geq 0$。 在本文中,我们假设$X$的基本群是线性的,即存在一个表示$\pi_1(X)\to {\rm GL}_N(\mathbb{C})$,其核是有限的。 我们通过证明一个更强的$L^2$退化定理来推导该猜想:对于此类$X$的万有覆盖空间$\widetilde{X}$,其$L^2$-Dolbeault 上同调$H_{(2)}^{n,q}(\widetilde{X})=0$对$q\neq 0$。 证明的主要工具是线性 Shafarevich 猜想中的技术以及一些解析方法。
In 1995, Koll\'ar conjectured that a smooth complex projective $n$-fold $X$ with generically large fundamental group has Euler characteristic $\chi(X, K_X)\geq 0$. In this paper, we prove the conjecture assuming $X$ has linear fundamental group, i.e., there exists a representation $\pi_1(X)\to {\rm GL}_N(\mathbb{C})$ with finite kernel. We deduce the conjecture by proving a stronger $L^2$ vanishing theorem: for the universal cover $\widetilde{X}$ of such $X$, its $L^2$-Dolbeault cohomology $H_{(2)}^{n,q}(\widetilde{X})=0$ for $q\neq 0$. The main ingredients of the proof are techniques from the linear Shafarevich conjecture along with some analytic methods.