# International conference "Approximation Theory and Applications"

International Conference "Approximation Theory and Applications" dedicated to the 100th anniversary of S.B. Stechkin will take place in Moscow from September 5 (arrival day) till September 11 (departure day), 2021. The conference will proceed in the hybrid format (in person and online via Zoom).

Accomodation: "Golden Ring Hotel", 5 Smolenskaya street, Moscow.

Offline meetings will take place in the room "Serguiev Posad", Golden Ring Hotel.

The conference is organized in cooperation with Steklov Institute and Moscow Center of Fundamental and Applied Mathematics.

**Video** (New!)

Program:

Monday, September 6: offline meeting

9:20-9:50 Participant registration

9:50-10:00 Opening of the conference

10:00-10:50 *S.V. Konyagin*, "On some papers of S.B. Stechkin";

11:00-11:50 *V.M. Tikhomirov*, "Approximation Theory and S.B. Stechkin's works";

Coffee-break

12:30-13:20 *S.Yu. Tikhonov*, "Smoothness conditions in approximation theory";

**Break**

15:00-15:30 *A.Yu. Popov*, "Sharp constants in the estimates of the sums of sine series with monotone convex coefficients";

15:30-15:55 *M.V. Balashov*, "Stability of minimization problems and the error bound conditions in the Hilbert space";

15:55-16:20 *N.Yu. Antonov*, "On the rate of convergence of Fourier sums of continuous functions with constraints on the fractality of their graphs";

16:20-16:45 *V.I. Filippov*, "Integer decomposition of elements of the spaces \(L_p\) in Fourier type series on systems of contractions and shifts of one function";

Coffee-break

17:05-17:30 *M.G. Plotnikov*, "Uniqueness for rearrangements of the trigonometric system";

17:30-17:55 *M.R. Gabdullin*, "Squares in a short interval is a \(\Lambda_4\)-set";

17:55-18:20 *P.G. Potseiko*, "Approximations on Classes of Poisson Integrals by Fourier–Chebyshev Rational Integral Operators" (joint with E. A. Rovba).

18:20-18:45 *R.R. Akopyan*, "Stechkin's problem on the classes of analytic functions".

**Break**

19:00 *Welcome buffet*

Tuesday, September 7: offline meeting

10:00-10:50 *A.Yu. Shadrin*, "On cardinality of the lower sets and their universal discretization";

11:00-11:50 *N.A. Ilyasov*, "S.B. Stechkin's inequalities in approximation theory: the key estimation and pairwise equivalency";

Coffee-break

12:30-13:20 *A.L. Lukashov*, "Interpolation by rational functions: several intervals; several variables";

**Break**

15:00-15:50 *M.G. Grigoryan*, "Existence and structure of universal functions in different senses";

16:00-16:30 *V.Yu. Protasov*, "Application of subdivision schemes to a problem of number theory";

16:30-16:55 *B.I. Golubov*, "Some results and problems in dyadic harmonic analysis";

Coffee-break

17:15-17:40 *M.A. Skopina*, "Wavelet approximation in Orlicz spaces";

17:40-18:05 *B.P. Osilenker*, "On Fourier series in orthogonal Sobolev’s polynomials";

18:05-18:30 *M.I. Dyachenko*, "The asymptotic of the sums of cosine-series with fractionely monotone coefficients near the origin";

18:30-18:55 *D.V. Gorbachev*, "Solving the Delsarte problems for spherical designs by the Arestov-Babenko method";

18:55-19:20 *S.Yu. Artamonov*, "Besov spaces with generalized smoothness and summability of multiple Fourier series".

Wednesday, September 8: online (zoom)

10:00-10:50 *V.I. Berdyshev*, "The movement of an object and an unfriendly observer";

11:00-11:50 *S. Révész*, "Fenton's sum of translates approach for classical minimax questions of approximation theory" (joint with Bálint Farkas, Béla Nagy);

**Break**

12:30-13:20 *V.V. Arestov*, "Approximation of invariant operators";

**Break**

14:30-15:00 *E.M. Semenov*, "Orthogonal elements of rearrangement invariant spaces";

15:00-15:30 *E. Kopecká*, "Approximating convex sets by simpler convex sets";

15:30-15:55 *K. Paul*, "\(k\)−smoothness of operators";

Break

16:10-16:40 *G.A. Karagulyan*, "On some inequalities for multiplicative sequences of functions";

16:40-17:05 *S.F. Lukomskii*, "Tight wavelet frames in zero dimensional groups";

17:05-17:30 *K. Kazaniecki*, "Translation invariant version of little Grothendieck theorem for Sobolev spaces";

Break

17:45-18:35 *G. Garrigos*, "The Haar basis in classical smoothness spaces";

18:45-19:35 *J. Sahasrabudhe*, "Flat Littlewood polynomials exist".

Thursday, September 9: offline meeting

10:00-10:50 *V.G. Krotov*, "The Fatou Property for General Approximate Identities on Metric Measure Spaces";

11:00-11:50 *V.N. Ushakov*, "On some control problems and approximation of sets in these problems" (joint with Uspenskii A.A., Lebedev P.D., Ershov A.A.);

Coffee-break

12:30-13:20 *I.G. Tsarkov*, "Caustics, Mach disks, application to astrophysics";

**Break**

15:00-15:30 *G.E. Ivanov*, "Existence and uniqueness of the nearest and farthest points of two subsets of a Banach space";

15:30-16:00 *A.R. Alimov*, "Some solar problems in max- and min-approximation";

16:00-16:25 *M.S. Lopushanski*, "Construction of rectifiable curves in proximally smooth sets";

16:25-16:50 *B.B. Bednov*, "On Chebyshev and monotone path-connected sets";

Coffee-break

17:10-17:35 *K.S. Shklyaev*, "Convex hull of a set in terms of metric projection";

17:35-18:00 *L.Sh. Burusheva*, "An example of a Banach space with non-Lipschitzian metric projection on any straight line".

**Break**

18:30 *Banquet*

Friday, September 10: online (zoom)

10:00-10:50 *R.M. Trigub*, "On the Fourier series and Fourier transforms";

11:00-11:50 *V.I. Ivanov*, "Weighted Inequalities in Dunkl Harmonic Analysis";

**Break**

12:30-13:20 *Yu.S. Volkov*, "Convergence of interpolation processes and conditionality of systems of equations for spline construction in the general problem of spline interpolation";

13:20-13:45 *T. Jahn*, "On the optimal constants in the two-sided Stechkin inequalities";

**Break**

14:30-15:20 *G.G. Gevorkyan*, "Uniqueness Theorems for Simple Trigonometric Series and its Application to Multiple Series";

15:30-16:00 *W. Sickel*, "S-Numbers of Embeddings of Weighted Wiener Classes";

16:00-16:25 *R. Schneider*, "Tree Based Tensor Networks (HT/TT) for the numerical solution of non-linear partial differential equations";

16:25-16:50 *P.Yu. Glazyrina*, "Turán's inequality, inverse to Markov's inequality, for compact sets in the complex plane";

Break

17:05-17:30 *D. Sain*, "Orthogonality and best approximations in Banach spaces";

17:30-17:55 *A. Ray*, "Bhatia-Semrl Property of a bounded linear operator";

17:55-18:20 *S. Gupta*, "Strong proximinality in Banach spaces";

18:20-18:45 *T. Nath*, "Differentiability of Distance Function and The Proximinal Condition implying Convexity".

Sections:

→ Approximation in Banach spaces.

→ Harmonic analysis and Multivariate approximation

Organizing commitee:

→ D.V. Treshchev (chair)

→ V.N. Temlyakov (chair)

→ S.V. Konyagin (chair)

→ Yu.V. Malykhin (deputy chair)

→ O.S. Goryainova (scientific secretary)

→ A.Yu. Shadrin

→ N.N. Andreev

→ V.E. Podolskii

Program commitee:

→ V.N. Berdyshev (chair)

→ N.Yu. Antonov

→ V.V. Arestov

→ O.V. Besov

→ V.I. Ivanov

→ B. Sendov

→ N.N. Kholshchevnikova

→ I.G. Tsarkov

→ N.I. Chernykh

→ A.Yu. Shadrin

Contacts: