scholarly journals A construction of complete complex hypersurfaces in the ball with control on the topology

2019 ◽  
Vol 2019 (751) ◽  
pp. 289-308 ◽  
Author(s):  
Antonio Alarcón ◽  
Josip Globevnik ◽  
Francisco J. López
Keyword(s):  
Unit Ball ◽  
Compact Subset ◽  
Unit Disc ◽  
Finite Topology ◽  
Complex Curves ◽  
Holomorphic Embedding ◽  
Holomorphic Embeddings

AbstractGiven a closed complex hypersurface {Z\subset\mathbb{C}^{N+1}} ({N\in\mathbb{N}}) and a compact subset {K\subset Z}, we prove the existence of a pseudoconvex Runge domain D in Z such that {K\subset D} and there is a complete proper holomorphic embedding from D into the unit ball of {\mathbb{C}^{N+1}}. For {N=1}, we derive the existence of complete properly embedded complex curves in the unit ball of {\mathbb{C}^{2}}, with arbitrarily prescribed finite topology. In particular, there exist complete proper holomorphic embeddings of the unit disc {\mathbb{D}\subset\mathbb{C}} into the unit ball of {\mathbb{C}^{2}}. These are the first known examples of complete bounded embedded complex hypersurfaces in {\mathbb{C}^{N+1}} with any control on the topology.

On growth of holomorphic embeddings into C2

2002 ◽  
Vol 132 (4) ◽  
pp. 879-889 ◽  
Author(s):  
Josip Globevnik
Keyword(s):  
Unit Disc ◽  
Open Unit ◽  
Open Unit Disc ◽  
Holomorphic Embedding ◽  
Holomorphic Embeddings

Let be the open unit disc in C. It is proved that a holomorphic embedding f : C2 can grow arbitrarily fast near b. It is also proved that a holomorphic embedding f : C C2 can grow arbitrarily fast near infinity.

6.—Rationally Convex Hulls and Potential Theory.

1976 ◽  
Vol 74 ◽  
pp. 81-89
Author(s):  
Richard F. Basener
Keyword(s):  
Potential Theory ◽  
Compact Subset ◽  
Unit Disc ◽  
Rational Functions ◽  
Continuous Functions ◽  
Uniform Algebra ◽  
Convex Hulls ◽  
Open Unit ◽  
Open Unit Disc ◽  
Image Position

SynopsisLet S be a compact subset of the open unit disc in C. Associate to S the setLet R(X) be the uniform algebra on X generated by the rational functions which are holomorphic near X. It is shown that the spectrum of R(X) is determined in a simple wayby the potential-theoretic properties of S. In particular, the spectrum of R(X) is X if and only if the functions harmonic near S are uniformly dense in the continuous functions on S. Similar results can be obtained for other subsets of C2 constructed from compact subsets of C.

The reproducing kernel of $\mathcal H^2$ and radial eigenfunctions of the hyperbolic Laplacian

2019 ◽  
Vol 124 (1) ◽  
pp. 81-101
Author(s):  
Manfred Stoll
Keyword(s):  
Hardy Space ◽  
Unit Ball ◽  
Hypergeometric Function ◽  
Compact Subset ◽  
Spherical Harmonics ◽  
Harmonic Functions ◽  
Reproducing Kernel ◽  
Diagonal Function ◽  
Hyperbolic Harmonic Functions

In the paper we characterize the reproducing kernel $\mathcal {K}_{n,h}$ for the Hardy space $\mathcal {H}^2$ of hyperbolic harmonic functions on the unit ball $\mathbb {B}$ in $\mathbb {R}^n$. Specifically we prove that \[ \mathcal {K}_{n,h}(x,y) = \sum _{\alpha =0}^\infty S_{n,\alpha }(\lvert x\rvert )S_{n,\alpha }(\lvert y\rvert ) Z_\alpha (x,y), \] where the series converges absolutely and uniformly on $K\times \mathbb {B}$ for every compact subset $K$ of $\mathbb {B}$. In the above, $S_{n,\alpha }$ is a hypergeometric function and $Z_\alpha $ is the reproducing kernel of the space of spherical harmonics of degree α. In the paper we prove that \[ 0\le \mathcal K_{n,h}(x,y) \le \frac {C_n}{(1-2\langle x,y\rangle + \lvert x \rvert^2 \lvert y \rvert^2)^{n-1}}, \] where $C_n$ is a constant depending only on $n$. It is known that the diagonal function $\mathcal K_{n,h}(x,x)$ is a radial eigenfunction of the hyperbolic Laplacian $\varDelta_h $ on $\mathbb{B} $ with eigenvalue $\lambda _2 = 8(n-1)^2$. The result for $n=4$ provides motivation that leads to an explicit characterization of all radial eigenfunctions of $\varDelta_h $ on $\mathbb{B} $. Specifically, if $g$ is a radial eigenfunction of $\varDelta_h $ with eigenvalue $\lambda _\alpha = 4(n-1)^2\alpha (\alpha -1)$, then \[ g(r) = g(0) \frac {p_{n,\alpha }(r^2)}{(1-r^2)^{(\alpha -1)(n-1)}}, \] where $p_{n,\alpha }$ is again a hypergeometric function. If α is an integer, then $p_{n,\alpha }(r^2)$ is a polynomial of degree $2(\alpha -1)(n-1)$.

scholarly journals An example of a non-exposed extreme function in the unit ball of H1

1994 ◽  
Vol 37 (1) ◽  
pp. 47-51 ◽  
Author(s):  
Jyunji Inoue
Keyword(s):  
Hardy Space ◽  
Unit Ball ◽  
Unit Disc ◽  
Inner Function ◽  
Classical Hardy Space

We construct a non-exposed extreme function f of the unit ball of H1, the classical Hardy space on the unit disc of the plane, which has the property: f(z)/(1−q(z))2 ∉ H1 for any nonconstant inner function q(z). This function constitutes a counterexample to a conjecture in D. Sarason [7].

Isometries of Bergman Spaces over Bounded Runge Domains

1981 ◽  
Vol 33 (5) ◽  
pp. 1157-1164 ◽  
Author(s):  
Clinton J. Kolaski
Keyword(s):  
Unit Ball ◽  
Hardy Spaces ◽  
Unit Disc ◽  
Bergman Spaces ◽  
Bounded Symmetric Domains ◽  
Several Variables ◽  
Special Cases

1.1. The isometries of the Hardy spaces Hp(0 < p < ∞, p ≠ 2) of the unit disc were determined by Forelli in [2]. Generalizations to several variables: For the polydisc the isometries of Hp onto itself were characterized by Schneider [9]. For the unit ball the case p > 2 was then done by Forelli [3]; Rudin [8] removed the restriction p > 2 by proving a theorem on equimeasurability. Finally, Koranyi and Vagi [6] noted that the methods developed by Forelli, Rudin and Schneider applied to bounded symmetric domains.In this note it will be shown that their methods also apply to the Bergman spaces over bounded Runge domains. The isometries which are onto are completely characterized; the special cases of the ball and polydisc are particularly nice and are given separately.

scholarly journals PROPAGATION OF SMALLNESS FOR SOLUTIONS OF GENERALIZED CAUCHY–RIEMANN SYSTEMS

2004 ◽  
Vol 47 (1) ◽  
pp. 191-204 ◽  
Author(s):  
E. Malinnikova
Keyword(s):  
Unit Ball ◽  
Lebesgue Measure ◽  
Compact Subset ◽  
Subject Classification ◽  
Positive Lebesgue Measure ◽  
Secondary 35B35 ◽  
Closed Set ◽  
Cauchy Riemann

AbstractLet $u$ be a solution of a generalized Cauchy–Riemann system in $\mathbb{R}^n$. Suppose that $|u|\le1$ in the unit ball and $|u|\le\varepsilon$ on some closed set $E$. Classical results say that if $E$ is a set of positive Lebesgue measure, then $|u|\le C\varepsilon^\alpha$ on any compact subset of the unit ball. In the present work the same estimate is proved provided that $E$ is a subset of a hyperplane and the (capacitary) dimension of $E$ is greater than $n-2$. The proof gives control of constants $C$ and $\alpha$.AMS 2000 Mathematics subject classification: Primary 31B35. Secondary 35B35; 35J45

scholarly journals On a conjecture of Z. Jianzhong

1992 ◽  
Vol 45 (1) ◽  
pp. 163-170
Author(s):  
Yasuo Matsugu
Keyword(s):  
Convex Function ◽  
Unit Ball ◽  
Unit Circle ◽  
Orlicz Space ◽  
Complex Plane ◽  
Unit Disc ◽  
Open Unit ◽  
Open Unit Disc ◽  
Almost All

Let ϕ be a nonnegative, nondecreasing and nonconstant function defined on [0, ∞) such that Φ(t) = ϕ(et) is a convex function on (-∞, ∞). The Hardy-Orlicz space H (ϕ) is defined to be the class of all those functions f holomorphic in the open unit disc of the complex plane C satisfying The subclass H(ϕ)+ of H(ϕ) is defined to be the class of all those functions f ∈ H(ϕ) satisfying for almost all points eit of the unit circle. In 1990, Z. Jianzhong conjectured that H(ϕ)+ = H(ψ)+ if and only if H(ϕ) = H(ψ). In the present paper we prove that it is true not only on the unit disc of C but also on the unit ball of Cn.

Isometries of Hp Spaces of Bounded Symmetric Domains

1976 ◽  
Vol 28 (2) ◽  
pp. 334-340 ◽  
Author(s):  
Adam Korányi ◽  
Stephen Vági
Keyword(s):  
Unit Ball ◽  
Hardy Spaces ◽  
Unit Disc ◽  
The State ◽  
Bounded Symmetric Domains ◽  
Several Variables ◽  
Hp Spaces ◽  
State Of Affairs

The isometries of the Hardy spaces Hv (0 < p < ∞, p ≠ 2) of the unit disc were determined by Forelli in 1964 [3]. For p = 1 the result had been found earlier by deLeeuw, Rudin and Wermer [2]. For several variables the state of affairs at present is this: For the polydisc the isometries of Hp onto itself have been characterized by Schneider [13]. For the unit ball the same result was proved in the case p > 2 by Forelli [4]. Finally in [12] Rudin removed the restriction p > 2 and also established some results about isometries of Hp of the ball and the polydisc into itself.

scholarly journals Embeddings of harmonic mixed norm spaces on smoothly bounded domains in ℝn

2019 ◽  
Vol 17 (1) ◽  
pp. 1260-1268
Author(s):  
Miloš Arsenović ◽  
Tanja Jovanović
Keyword(s):  
Unit Ball ◽  
Bounded Domain ◽  
Maximal Function ◽  
Unit Disc ◽  
Harmonic Functions ◽  
Type Operator ◽  
Mixed Norm ◽  
Bounded Domains ◽  
Function Type ◽  
Mixed Norm Spaces

Abstract The main result of this paper is the embedding $$\begin{array}{} \displaystyle \mathcal{B}^{s,r}_\beta({\it\Omega})\hookrightarrow \mathcal{B}^{s_1,r_1}_{\beta+(n-1)\big(\frac 1s-\frac 1{s_1}\big)}({\it\Omega}), \end{array}$$ 0 < r ≤ r1 ≤ ∞, 0 < s ≤ s1 ≤ ∞, β > –1, of harmonic functions mixed norm spaces on a smoothly bounded domain Ω ⊂ ℝn. We also extend a result on boundedness, in mixed norm, of a maximal function-type operator from the case of the unit disc and the unit ball to general domains in ℝn.

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