Contents

Doklady Mathematics

Vol. 104, No. 2, 2021

Mathematics

Numerical Study of the Zaremba Problem

S. D. Algazin p. 225  abstract

On Gaussian Transition Operators

G. A. Alekseev, K. A. Afonin and V. I. Bogachev p. 229  abstract

Axiomatic Definition of Small Cancellation Rings

A. Atkarskaya, A. Kanel-Belov, E. Plotkin and E. Rips p. 234  abstract

Periodic Ultradiscrete Plane Transformations

Corresponding Member of the RAS V. A. Bykovskii p. 240  abstract

On Some Modifications of Arnold’s Cat Map

S. D. Glyzin and A. Yu. Kolesov p. 242  abstract

On the 4-Spectrum of First-Order Properties of Random Graphs

M. E. Zhukovskii, A. D. Matushkin and Yu. N. Yarovikov p. 247  abstract

Comparison Theorems for Elliptic Inequalities with Lower-Order Derivatives That Take into Account the Geometry of the Domain

A. A. Kon’kov p. 250  abstract

Mathematical Modeling of 3D Dynamic Processes near a Fracture Using the Schoenberg Fracture Model

Corresponding Member of the RAS I. B. Petrov, P. V. Stognii and N. I. Khokhlov p. 254  abstract

On the Periodicity Problem for the Continued Fraction Expansion of Elements of Hyperelliptic Fields with Fundamental S-Units of Degree at Most 11

Academician of the RAS V. P. Platonov, M. M. Petrunin and Yu. N. Shteinikov p. 258  abstract

Group Structures on Algebraic Varieties

Corresponding member of the RAS V. L. Popov p. 264  abstract

Self-Affine Tiling of Polyhedra

Corresponding Member of the RAS V. Yu. Protasov and T. I. Zaitseva p. 267  abstract

Correct Solvability and Exponential Stability for Solutions of Volterra Integro-Differential Equations

N. A. Rautian p. 273  abstract

Existence and Stability of Equilibrium Solutions of the Vlasov Equation with a Modified Gravitational Potential

T. V. Salnikova p. 277  abstract

The Second Boundary Value Problem for Differential-Difference Equations

A. L. Skubachevskii and N. O. Ivanov p. 282  abstract

New Cases of Integrability of Systems of Geodesics and Potential and Dissipative Systems on Tangent Bundles of Finite-Dimensional Manifolds

M. V. Shamolin p. 285  abstract

Adaptive Gauss–Newton Method for Solving Systems of Nonlinear Equations

N. E. Yudin p. 293  abstract

Computer Science

Application of the Multiscale Approach to Simulation of Air Sorbent Filtration

S. V. Polyakov, T. A. Kudryashova and N. I. Tarasov p. 297  abstract

Control Processes

Sub-Riemannian Engel Sphere

Yu. L. Sachkov and A. Yu. Popov p. 301  abstract

Attraction for Mechanical Systems with Friction

I. A. Finogenko p. 306  abstract

Anisotropy-Based Approach to Communication Tuning for a Time-Varying Sensor Network System

A. V. Yurchenkov and A. Yu. Kustov p. 311  abstract