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Индекс Морса седловых состояний равновесия градиентно-подобных потоков на связной сумме Sn−1×S1
Математические заметки. 2022. Т. 111. № 4. С. 616–619.
The paper proves that the Morse index (dimension of an unstable manifold) of any saddle equliblrium state of a gradient-like flow without heteroclinic intersections, defined on a connected sum of S^{n-1}\times S^1, n>3, equals either 1 or ( n-1).
Gusev I., Maksaev A., Promyslov V., Journal of Mathematical Sciences 2025 Vol. 299 No. 6
The regular graph of the space of n × m matrices over a field F is defined as the undirected graph whose vertices are matrices of rank min(n, m), and distinct matrices A and B are connected by an edge if and only if rk(A + B) < min(n, m). In this paper, for |F| ...
Added: May 25, 2026
Tyukin I., Tyukina T., van Helden D. P. et al., Information Sciences 2024 Vol. 678 Article 120856
AI errors pose a significant challenge, hindering real-world applications. This work introduces a novel approach to cope with AI errors using weakly supervised error correctors that guarantee a specific level of error reduction. Our correctors have low computational cost and can be used to decide whether to abstain from making an unsafe classification. We provide ...
Added: May 23, 2026
Zaikin A., Sviridov I., Sosedka A. et al., Technologies 2026 Vol. 14 No. 2 Article 84
High-dimensional tabular data are common in biomedical and clinical research, yet conventional machine learning methods often struggle in such settings due to data scarcity, feature redundancy, and limited generalization. In this study, we systematically evaluate Synolitic Graph Neural Networks (SGNNs), a framework that transforms high-dimensional samples into sample-specific graphs by training ensembles of low-dimensional pairwise ...
Added: May 23, 2026
Kibkalo Vladislav, Chertopolokhov V., Mukhamedov A. et al., IEEE Access 2026 Vol. 14 P. 14369–14392
This study presents on-the-fly identification and multi-step prediction of nonlinear systems with delayed inputs using a dynamic neural network combined with a smooth projection onto ellipsoids. The projection enforces parameter constraints that guarantee stability, while a Lyapunov–Krasovskii analysis yields computable ultimate error bounds. Riccati-type matrix inequalities are derived, providing an efficient vectorization–projection–devectorization implementation suitable for ...
Added: May 22, 2026
Морозов С. В., Calcolo 2026 Vol. 63 No. 2 Article 23
The approximation of tensors in a low-para metric format is a crucial component in many mathematical modelling and data analysis tasks. Among the widely used low-parametric representations, the canonical polyadic (CP) decomposition is known to be very efficient. Nowadays, most algorithms for CP approximation aim to construct the approximation in the Frobenius norm; however, some ...
Added: May 22, 2026
Селянин Ф. И., Journal of Dynamical and Control Systems 2026 Vol. 32 No. 2 P. 1–16
A B-facet is a lattice -dimensional polytope in the positive octant with a positive normal covector, such that every -dimensional simplex with vertices in it is a B-simplex (i.e., a pyramid of height one with base on a coordinate hyperplane). B-facets were introduced in [2] in the context of the monodromy conjecture. In this paper, we complete the ...
Added: May 21, 2026
Ausubel L., Baranov O., Journal of Economic Theory 2026 Vol. 235 No. 106192
The Vickrey-Clarke-Groves (VCG) mechanism is one of the most compelling constructs in mechanism design, but the presence of complementary goods creates the possibility of non-core and even zero-revenue outcomes. In this article, we show that joint feasibility constraints on allocations offer a second pathway to ill-behaved outcomes in the VCG mechanism, even when all bidders ...
Added: May 20, 2026
Denis Seliutskii, Russian Journal of Mathematical Physics 2025 Vol. 32 No. 2 P. 399–407
In this paper, we find an upper bound for the first Steklov eigenvalue for a surface of revolution with boundary consisting of two spheres of different radii. Moreover, we prove that, in some cases, this boundary is sharp. ...
Added: May 19, 2026
Жакупов О. Б., European Journal of Mathematics 2025 Vol. 11 Article 84
We provide examples of smooth three-dimensional Fano complete intersections of degree 2, 4, 6, and 8 that have absolute coregularity 0. Considering the main theorem of Avilov, Loginov, and Przyjalkowski (CNTP 18:506–577, 2024) on the remaining 101 families of smooth Fano threefolds, our result implies that each family of smooth Fano threefolds has an element of absolute ...
Added: May 18, 2026
Gonchenko S., Lerman L., Turaev D., Regular and Chaotic Dynamics 2026 Vol. 31 No. 3 P. 349–369
We show that bifurcations of four-dimensional symplectic diffeomorphisms with a quadratic homoclinic tangency to a saddle periodic orbit with real multipliers produce 2-elliptic periodic orbits if the tangency is not partially hyperbolic. We show that a normal form for the rescaled first-return maps near such tangency is given by a four-dimensional symplectic H´enonlike map and study bifurcations of the ...
Added: May 15, 2026
Aleskerov F. T., Khutorskaya O., Stepochkina A. et al., Springer, 2026.
The book contains new models of bibliometric analysis based on centrality measures in network analysis, pattern analysis and stability analysis. A distinctive feature of these centrality measures is that they account for the parameters of vertices and group influence of vertices to a vertex. This reveals specific groups of publications, authors, terms, journals and affiliations ...
Added: May 15, 2026
Kuptsov P., Panyushev A., Stankevich N., Chaos 2026 Vol. 36 No. 5 Article 053138
We develop a machine-learning approach to reproduce the behavior of two versions of the van der Pol oscillator exhibiting a subcritical Andronov–Hopf bifurcation, with or without a codimension-2 Bautin point. We construct a neural-network model that functions as a recur rent map and train it on short segments of oscillator trajectories. The results show that, ...
Added: May 15, 2026
Dorovskiy A., / Series arXiv "math". 2026.
In this paper the structural stability of generic families of vector fields of the PC-HC class on the two-dimensional sphere is proved. A classification of these families up to moderate equivalence in neighborhoods of their large bifurcation supports is presented, based on such invariants as the configuration and the characteristic set. The realization lemma is proved. ...
Added: May 14, 2026
Lebedev V., Journal of Mathematical Analysis and Applications 2026 Vol. 563 No. 2 Article 130787
It is known that for every continuous real-valued
function $f$ on the circle $\mathbb T=\mathbb R/2\pi\mathbb Z$ there exists a
change of variable, i.e., a self-homeomorphism $h$ of $\mathbb T$, such that
the superposition $f\circ h$ is in the Sobolev space $W_2^{1/2}(\mathbb T)$.
We obtain new results on simultaneous improvement of functions by a single
change of variable in relation ...
Added: May 14, 2026
Blokh A., Oversteegen L., Selinger N. et al., Arnold Mathematical Journal 2026 Vol. 12 No. 1 P. 60–110
We describe a model for the boundary of the connectedness locus of the parameter space of cubic symmetric polynomials. We show that there exists a monotone continuous function from the connectedness locus to the model which is a homeomorphism if the former is locally connected. ...
Added: May 13, 2026
Petrov I., Автоматика и телемеханика 2026 № 6 С. 82–118
Системам связанных агентов и сетевому управлению посвящено большое число отечественных и зарубежных исследований. Исторически, наибольший интерес в теории управления возникал к усредняющим системам и, в частности, к задаче консенсуса. Однако сетевое взаимодействие может характеризоваться более специфическими функциями, отражающими зависимость от действий соседей по сети, что особенно явно проявляется в моделях стратегического взаимодействия на сети, которое ...
Added: May 12, 2026
Galkin V., Pochinka O., Успехи математических наук 2026 Т. 81 № 2(422) С. 71–144
Настоящая работа посвящена изучению динамики регулярных четырехмерных потоков, их топологической классификации и взаимосвязи с топологией несущего многообразия. Регулярные потоки являются топологическими аналогами потоков Морса–Смейла. Их появление мотивировано двумя фактами: 1) существованием топологических многообразий размерности 4 и выше, не имеющих гладкой структуры; 2) развитием методов топологической классификации гладких систем, использующих чисто топологические свойства этих систем и ...
Added: April 1, 2026
Pochinka O., Chilina E., Математический сборник 2026 Т. 217 № 3 С. 112–134
Работа посвящена исследованию сохраняющих ориентацию гомеоморфизмов трехмерных многообразий с неблуждающим множеством, состоящим из конечного числа двумерных аттракторов и репеллеров, каждый из которых является дизъюнктным объединением цилиндрически вложенных замкнутых поверхностей, ограничение некоторой степени на каждую из которых топологически сопряжено сохраняющему ориентацию псевдоаносовскому гомеоморфизму. Получена топологическая классификация модельных гомеоморфизмов, реализованных на каждом многообразии, допускающем гомеоморфизмы исследуемого класса. Доказано, ...
Added: March 3, 2026
Мартынов Т. Д., Pochinka O., Chilina E., Математика и теоретические компьютерные науки 2025 Т. 3 № 3 С. 87–109
According to J. Nielsen and H. Hang, each class of topological conjugacy of periodic homeomorphisms of orientable compact surfaces is completely described by a finite set of data called the characteristic. For a two-dimensional sphere, exhaustive classification results with the construction of linear representatives in each conjugacy class were obtained by B. Kerekyarto. For a ...
Added: October 18, 2025
Gurevich E., Математика и теоретические компьютерные науки 2025 Т. 3 № 3 С. 20–42
A topological classification of smooth, structurally stable flows on four-dimensional closed manifolds is obtained, the wandering set of which contains isolated trajectories connecting saddle equilibria (heteroclinic curves). For dimensional reasons, the heteroclinic curves of such flows belong to the intersection of invariant manifolds of saddles of adjacent Morse indices. We assume that the non-wandering set of ...
Added: October 18, 2025
Gurevich E., Saraev I., Communications in Nonlinear Science and Numerical Simulation 2026 Vol. 152 No. D Article 109301
We consider homeomorphisms with a finite and topologically hyperbolic chain-recurrent set and explore the interrelation between the structure of the chain-recurrent set and the topology of carrying manifolds of dimension n > 3. We demonstrate that the Lefschetz fixed-point theorem can be refined for this class of homeomorphisms as follows: if the (n-1)-dimensional invariant manifold ...
Added: October 4, 2025
Medvedev V., Egor Morozov, Mathematische Nachrichten 2025 Vol. 298 No. 9 P. 3007–3026
Fraser-Sargent surfaces are free boundary minimal surfaces in the four-dimensional unit Euclidean ball. Extended infinitely they define immersed minimal surfaces in the Euclidean space. The parts of these surfaces outside the ball are exterior free boundary minimal surfaces. We prove that they are stable. Independently of it, we find an upper bound on the index ...
Added: September 30, 2025
Galkin V., Pochinka O., Математические заметки 2025 Т. 117 № 6 С. 861–878
Под регулярным топологическим потоком на замкнутом nn-многообразии понимается поток, цепно рекуррентное множество которого состоит из конечного числа топологически гиперболических неподвижных точек и периодических орбит. Такой поток называется неособым, если его цепно рекуррентное множество не содержит неподвижных точек. Топологической эквивалентности маломерных неособых потоков в предположениях различной общности посвящен целый ряд работ. Начиная с размерности 4 имеется пока незначительное число ...
Added: June 2, 2025
Egor Morozov, Mathematical Physics Analysis and Geometry 2024 Vol. 27 P. 1–23
For each rational number $p/q\in (1/2,\sqrt 2/2)$ one can construct an $\mathbb S^1$-equivariant minimal torus in $\mathbb S^3$ called Otsuki torus and denoted by $O_{p/q}$. The Lawson's bipolar surface construction applied to $O_{p/q}$ gives a minimal torus $\widetilde O_{p/q}$ in $\mathbb S^4$. In this paper we give upper and lower bounds on the Morse index ...
Added: April 29, 2025