Researches in Mathematics

Announcement, July 2025: The editorial board of the scientific journal Researches in Mathematics announces that in 2025 we plan additional special issue of the journal Researches in Mathematics on Approximation Theory (Vol. 33, No. 2, 2025), dedicated to the memory of outstanding mathematician, corresponding member of NAS of Ukraine, honorary member of the editorial board, editor-in-chief of the journal for many years, Prof. V.P. Motornyi.

The journal publishes, semiannually, research articles in basic areas of theoretical and applied mathematics, including, but not limited to: analysis, algebra, geometry, topology, probability theory and mathematical statistics, differential equations and mathematical physics.

The journal was published annually from 1963 to 1997 under the title “Researches on modern problems of summation and approximation of functions and their applications” and from 1998 to 2018 under the title “Dnipro University Mathematics Bulletin”.

Since 2022, the journal has been included to Scopus.

Attention: The template of the submission (.tex and .cls files) was updated on 20.12.2025. Please proceed to Author Guidelines to download and use the latest version.


Vol 33, No 2 (2025)

Special Issue on Approximation Theory

Dedicated to the memory of Corresponding Member of the National Academy of Sciences of Ukraine, Professor V. P. MOTORNYI

Published: online 12.12.2025

Table of Contents

Preamble
 
PDF
1-2

Articles

In memoriam: Professor Vitalii Pavlovych Motornyi (1940 – 2025)
 
PDF (Українська)
3-5
The Taikov type inequalities in rigged Hilbert spaces
V. Babenko, Yu. Babenko, N. Kriachko, D. Skorokhodov
PDF
6-18
Inequalities for $$$\Lambda$$$-derivatives of functions defined on a metric space and some of their applications
V. Babenko, V. Kolesnyk, O. Kovalenko, N. Parfinovych
PDF
19-31
On the growth of gap power series of homogeneous polynomials
A.I. Bandura, M.M. Dolynyuk, O.B. Skaskiv
PDF
32-39
Best weighted approximation of some kernels on the real axis
S.O. Chaichenko, V.V. Savchuk, A.L. Shydlich
PDF
40-51
Error bounds for numerical differentiation using kernels of finite smoothness
O.V. Davydov
PDF
52-64
On the analytical continuation of the ratio $$$H_4(\alpha,\delta+1;\gamma,\delta;-\mathbf{z})/H_4(\alpha,\delta+2;\gamma,\delta+1;-\mathbf{z})$$$
R. Dmytryshyn, C. Cesarano, I.-A. Lutsiv
PDF
65-76
Boyanov-Naydenov problem and Kolmogorov type inequalities for positive (negative) parts of functions
V.A. Kofanov
PDF
77-91
A simple algorithm for expanding a formal triple power series as a three-dimensional associated continued fractions
Kh.Yo. Kuchminska, R.M. Deyneka
PDF
92-98
Equivalence between various Shape Preserving Approximations of periodic functions
D. Leviatan, O.V. Motorna, I.O. Shevchuk
PDF
99-107
The homotopy groups $$$\pi_k(\Omega_n(m))$$$, $$$k=1,...,n$$$
A.M. Pasko
PDF
108-110
The best $$$m$$$-term trigonometric approximations of the classes of periodic multivariate functions of mixed smoothness
K.V. Pozharska, A.S. Romanyuk
PDF
111-127
Estimates of deviations of Fourier sums on Weyl-Nagy classes $$$W^r_{\beta,1}$$$
A.S. Serdyuk, I.V. Sokolenko
PDF
128-138
The best linear approximation methods for classes of functions analytic in a disk and exact values of their $$$n$$$-widths
S.B. Vakarchuk, M.B. Vakarchuk
PDF
139-158