Abstract
Let \(f\) be an entire function of finite type with respect to finite order \(\rho {\text{ in }}\mathbb{C}^n \) and let \(\mathbb{E}\) be a subset of an open cone in a certain n-dimensional subspace \(\mathbb{R}^{2n} {\text{ ( = }}\mathbb{C}^n {\text{)}}\) (the smaller \(\rho \), the sparser \(\mathbb{E}\)). We assume that this cone contains a ray \(\left\{ {z = tz^0 \in \mathbb{C}^n :t > 0} \right\}\). It is shown that the radial indicator \(h_f (z^0 )\) of \(f\) at any point \(z^0 \in \mathbb{C}^n \backslash \{ 0\} \) may be evaluated in terms of function values at points of the discrete subset \(\mathbb{E}\). Moreover, if \(f\) tends to zero fast enough as \(z \to \infty \) over \(\mathbb{E}\), then this function vanishes identically. To prove these results, a special approximation technique is developed. In the last part of the paper, it is proved that, under certain conditions on \(\rho \) and \(\mathbb{E}\), which are close to exact conditions, the function \(f\) bounded on \(\mathbb{E}\) is bounded on the ray.
Similar content being viewed by others
REFERENCES
P.Lelong, "Fonctions plurisousharmoniques et fonctions analytiques reeles," Ann. Fast. Fourier, 11, 263–303 (1961).
L. I. Ronkin, Introduction to the Theory of Entire Functions of Several Variables, American Mathematical Society, Providence (1974).
V. Bernstein, "Sur les proprietes caracteristiques des indicatrices de croissance," C. R., 202, 108–110 (1936).
A. Pfluger "Über das Anwachsen von Funktionen, die in einem Winkelraum reqular und von Exponentialtypus sind," Compos. Math., 4., 367–372 (1937).
N. Levinson, Gap and Density Theorems, American Mathematical Society, New York (1940).
R. P. Boas, "On the growth of analytic functions," Duke Math. J., 13, 433–448 (1936).
W. H. I. Fuchs, "On the growth of functions of mean type," Proc. Edinburgh Math. Soc., 9, 53–70 (1954).
B. Ja. Levin, Distribution of Zeros of Entire Functions, American Mathematical Society, Providence (1964).
P. Malliavin, "Sur le croissance radiale d'une fonction meromorphe," III. J. Math., 1, 256–296 (1957).
L. I. Ronkin, "On discrete uniqueness sets for entire functions of exponential type and several variables," Sib. Mat. Zh., 19, 142–152 (1978).
V. N. Logvinenko, "On entire functions of exponential type bounded or slowly growing along the real hyperplane," Sib. Mat. Zh., 29, 126–138 (1988).
M. V. Keldysh, "Sur l'approximation des fonctions holomorphes par les fonctions entiers," Dokl. Akad. Nauk SSSR, 47, 239–241 (1946).
A. Russakovskii, "Approximation by entire functions on unbounded domains in ℂ n," J. Approxim. Theory, 70, 353–358 (1993).
V. Logvinenko and A. Russakovskii, Quasi-Sampling Sets for Functions Analytic in a Cone, Preprint (1995).
V. Logvinenko and N. Chystyakova, "Polynomial approximation on varying sets," J. Approxim. Theory,86, 144–178 (1996).
A. C. Schaeffer, "Entire functions and trigonometric polynomials," Duke Math J., 20, 77–78 (1953).
B. Ja. Levin, "Majorants in classes of subharmonic functions," Teor. Funkts., Funkts. Anal. Prilozhen., 51, 3–17 (1989).
V. E. Katznelson, "Equivalent norms in spaces of entire functions," Mat. Sb., 92(134), 34–54 (1973).
B. Ja. Levin and V. N. Logvinenko, "On classes of functions subharmonic in ℝn and bounded on some subsets," Zap. Nauchn. Sem. LOMI, 170, 157–175 (1989).
B. Ja. Levin, V. N. Logvinenko, and M. L. Sodin, "Subharmonic functions on finite degree bounded on subsets of the 'Real Hyperplane,' " Adv. Sov. Math., 11, 181–197 (1992).
Author information
Authors and Affiliations
Rights and permissions
About this article
Cite this article
Logvinenko, V., Nazarova, N. Bernstein-Type Theorems and Uniqueness Theorems. Ukrainian Mathematical Journal 56, 244–263 (2004). https://doi.org/10.1023/B:UKMA.0000036099.14798.f9
Issue Date:
DOI: https://doi.org/10.1023/B:UKMA.0000036099.14798.f9