Abstract:In 2002 A. Hartmann and X. Massaneda obtained necessary and sufficient conditions for interpolation sequences for classes of analytic functions in the unit disc such that log M (r, f ) = O((1 − r) −ρ ), 0 < r < 1, ρ ∈ (0, +∞), where M (r, f ) = max{|f (z)| : |z| = r}. Using another method, we give an explicit construction of an interpolating function in this result. As an application we describe minimal growth of the coefficient a such that the equation f ′′ + a(z)f = 0 possesses a solution with a prescribed s… Show more
“…The rest of the proof of Theorem 2.1 repeats that of Theorem F [3]. It consists in estimating of the interpolating function…”
Section: Lemma I (Chyzhykov and Sheparovych [3 Proposition 11]) Given A Functionmentioning
confidence: 75%
“…Its proof literally repeats that of Theorem C [3] with the only difference that we apply Theorem 2.1 instead of Theorem F. The same scheme is used in the proof of Theorem 2.5. In particular, after the substitution f (z) = P (z)e g (z) where g(z) is analytic in D, P (z) is the canonical product (2.2), the construction of an analytic function a reduces to the interpolation problem of finding an analytic function…”
Section: Resultsmentioning
confidence: 94%
“…Proof of Theorem 2.1. We follow the scheme of the proof of Theorem F from [3]. It follows from the estimate (2.3) and [3,Lemma 9]…”
Section: Proofs Of the Resultsmentioning
confidence: 99%
“…Note that the proof of sufficiency in [11] uses a non-constructive method of L 2 -estimate for the solution to a∂-equation. On the other hand, in [3], an interpolating function is constructed explicitly. The following theorem gives sufficient conditions for interpolation sequences in classes of analytic functions of moderate growth in the unit disc.…”
Let
$(z_k)$
be a sequence of distinct points in the unit disc
$\mathbb {D}$
without limit points there. We are looking for a function
$a(z)$
analytic in
$\mathbb {D}$
and such that possesses a solution having zeros precisely at the points
$z_k$
, and the resulting function
$a(z)$
has ‘minimal’ growth. We focus on the case of non-separated sequences
$(z_k)$
in terms of the pseudohyperbolic distance when the coefficient
$a(z)$
is of zero order, but
$\sup _{z\in {\mathbb D}}(1-|z|)^p|a(z)| = + \infty$
for any
$p > 0$
. We established a new estimate for the maximum modulus of
$a(z)$
in terms of the functions
$n_z(t)=\sum \nolimits _{|z_k-z|\le t} 1$
and
$N_z(r) = \int_0^r {{(n_z(t)-1)}^ + } /t{\rm d}t.$
The estimate is sharp in some sense. The main result relies on a new interpolation theorem.
“…The rest of the proof of Theorem 2.1 repeats that of Theorem F [3]. It consists in estimating of the interpolating function…”
Section: Lemma I (Chyzhykov and Sheparovych [3 Proposition 11]) Given A Functionmentioning
confidence: 75%
“…Its proof literally repeats that of Theorem C [3] with the only difference that we apply Theorem 2.1 instead of Theorem F. The same scheme is used in the proof of Theorem 2.5. In particular, after the substitution f (z) = P (z)e g (z) where g(z) is analytic in D, P (z) is the canonical product (2.2), the construction of an analytic function a reduces to the interpolation problem of finding an analytic function…”
Section: Resultsmentioning
confidence: 94%
“…Proof of Theorem 2.1. We follow the scheme of the proof of Theorem F from [3]. It follows from the estimate (2.3) and [3,Lemma 9]…”
Section: Proofs Of the Resultsmentioning
confidence: 99%
“…Note that the proof of sufficiency in [11] uses a non-constructive method of L 2 -estimate for the solution to a∂-equation. On the other hand, in [3], an interpolating function is constructed explicitly. The following theorem gives sufficient conditions for interpolation sequences in classes of analytic functions of moderate growth in the unit disc.…”
Let
$(z_k)$
be a sequence of distinct points in the unit disc
$\mathbb {D}$
without limit points there. We are looking for a function
$a(z)$
analytic in
$\mathbb {D}$
and such that possesses a solution having zeros precisely at the points
$z_k$
, and the resulting function
$a(z)$
has ‘minimal’ growth. We focus on the case of non-separated sequences
$(z_k)$
in terms of the pseudohyperbolic distance when the coefficient
$a(z)$
is of zero order, but
$\sup _{z\in {\mathbb D}}(1-|z|)^p|a(z)| = + \infty$
for any
$p > 0$
. We established a new estimate for the maximum modulus of
$a(z)$
in terms of the functions
$n_z(t)=\sum \nolimits _{|z_k-z|\le t} 1$
and
$N_z(r) = \int_0^r {{(n_z(t)-1)}^ + } /t{\rm d}t.$
The estimate is sharp in some sense. The main result relies on a new interpolation theorem.
We obtaine the conditions on a sequence (bhas the unique solution in a subspace of entire functions g satisfying the condition ln M g (r) ≤ c 1 exp (N (r) + N (ρ 1 r)), where |λ k /λ k+1 | ≤ ∆ < 1, and N (r) is the Nevanlinna counting function of the sequence (λ k ). These results have been applied to describe solutions of the differential equation f ′′ + a 0 f = 0 with a coefficient a 0 from the some space of entire functions.
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