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JOURNALS // Zapiski Nauchnykh Seminarov POMI // Archive

Zap. Nauchn. Sem. LOMI, 1979 Volume 92, Pages 253–258 (Mi znsl3202)

Short communications

All closed ideals, of the algebra $A_\varphi(\mathbb C)$ are divisorial

S. A. Apresyan


Abstract: Let $\lambda$ be an increasing function on the half-line (satis fying some regularity growth conditions), $A_\lambda$ the algebra of all entire functions $f$ satisfying $\log|f(z)|=0(\lambda(|z|))$ ($|z|\to\infty$). It is proved that every closed ideal $I$ of the algebra $A_\lambda$ is divisorial, i.e.  $I=I_k\overset{\text{def}}=\{f\in A_\lambda:k_f(\xi)\ge k_I(\xi),\xi\in\mathbb C\}$, $k_f(\xi)$ being the multiplicity of the zero of $f$ at $\xi$, $k_I(\xi)=\min_{f\in I}k_f(\xi)$, $\xi\in\mathbb C$. It is shown that $f\equiv0$ provided $f\in A_\lambda$,
$$ \lim_{\substack{\xi\in\gamma\\|\xi|\to\infty}}\frac{\log|f(\xi)|}{\lambda(|\xi|)}=-\infty $$
where $\gamma$ denotes continuous curve joining the origin with the infinity.

UDC: 517.54



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