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JOURNALS // Matematicheskii Sbornik // Archive

Mat. Sb., 2025 Volume 216, Number 12, Pages 25–56 (Mi sm10188)

Density functions with respect to a model growth function

M. V. Kabanko, K. G. Malyutin, T. I. Malyutina

Faculty of Physics, Mathematics, Computer Science, Kursk State University, Kursk, Russia

Abstract: The properties of general density functions with respect to a model growth function $M$ and related semiadditive functions are discussed. The concept of function of slow growth with respect to the model growth function $M$ is introduced; it is shown that the function $L(r)=M^{-\rho}(r)V(r))$ has a slow growth with respect to $M$. The concept of $\rho$-semiadditive function with respect to $M$ is also introduced, and the main properties of such functions are established. Density functions are studied; a criterion of the continuity of the density $N_M(\alpha)$ and lower density $\underline N_M(\alpha)$ of a function $f$ is obtained. A uniformity theorem is proved. The main properties of $\rho$-additive and $\rho$-semiadditive functions with respect to the model function $M$ are presented. One of the central results is a theorem that can be viewed as an extension of Pólya's theorem on the existence of minimal and maximal densities to a wider class of functions, whose growth is bounded by an arbitrary model growth function $M$. Examples of functions $f$ and their density functions are presented.
Bibliography: 17 titles.

Keywords: model growth function, semiadditive function, density function, minimal and maximal densities, Pólya's theorem.

MSC: 26A12

Received: 11.09.2024 and 17.01.2025

DOI: 10.4213/sm10188


 English version:
Sbornik: Mathematics, 2025, 216:12, 1664–1692


© Steklov Math. Inst. of RAS, 2026