Methods of Functional Analysis
and Topology
Editors-in-Chief: A. N. Kochubei,
G. M. Torbin
ISSN: 1029-3531 (Print), 2415-7503 (Online)
Founded by Yu. M. Berezansky in 1995.
Methods of Functional Analysis and Topology (MFAT), founded in 1995, is a peer-reviewed journal publishing original articles and surveys on general methods and techniques of functional analysis and topology with a special emphasis on applications to modern mathematical physics.
MFAT is an open access journal, free for authors and free for readers.
Indexed in: MathSciNet, zbMATH, Scopus, Web of Science, DOAJ, Google Scholar
Latest Articles (December, 2025)
On faithfulness, DP-transformations and Cantor series expansions
Grygoriy Torbin, Yuliia Voloshyn
MFAT 31 (2025), no. 4, 360-370
360-370
The paper is devoted to the study of conditions for the Hausdorff-Besicovitch faithfulness of the family of cylinders generated by Cantor series expansions.
We show that there exist subgeometric Cantor series expansions for which the corresponding families of cylinders are not faithful for the Hausdorff-Besicovitch dimension on the unit interval. On the other hand we found a rather
wide subfamily of subgeometric Cantor series expansions generating faithful families of cylinders.
We also study conditions for the Hausdorff-Besicovitch dimension preservation on [0;1] by probability distribution functions of random variables with independent symbols of arithmetic Cantor series expansions.
New Definition of $\mathcal{N}^{\alpha}_F$-Sumudu conformable transform
Bahloul Rachid, Rachad Houssame
MFAT 31 (2025), no. 4, 336-343
336-343
Using the new definition of the $\mathcal{N}^{\alpha}_F$-derivative function introduced by Juan E. Nápoles Valdés and al. (2020), we provide a new definition for the $\mathcal{N}^{\alpha}_F$-Sumudu transform, $\mathcal{N}^{\alpha}_F$-Sumudu conformable transform. Additionally, we establish several important results related to these new transforms. We also give a new definition of convolution related to this $\mathcal{N}^{\alpha}_F$-derivative and we show that it is commutative and associative.
On the reduction of a Gram operator that corresponds to a multirooted graph
MFAT 31 (2025), no. 4, 344-359
344-359
Any abstract Gram operator is consistent with some graph. For an arbitrary operator $B_\Gamma$ that is consistent with a graph $\Gamma$, the question arises as to when it is an abstract Gram operator, i.e., whether it is nonnegative. We study this question for certain types of graphs. The simplest case is a star graph. Next, we use the results obtained for star graphs to explore a more general case, where a graph $\Gamma$ can be treated as a collection of rooted trees, with their roots connected by additional edges into a connected subgraph $\Gamma_0$. The work shows that the question about the nonnegativity of an operator $B_\Gamma$ for such a graph can be reduced to the corresponding question for some operator that is consistent with the subgraph $\Gamma_0$.
Laguerre-Bessel Wavelet Packets Transform
MFAT 31 (2025), no. 4, 325-335
325-335
In this paper, the Laguerre-Bessel wavelet packets transform is defined and studied. The scale discrete scaling function and the associated Plancherel and inversion formulas are given and established. Furthermore, the Calderón reproducing formula is given and proved for the proposed transform.