01.01.01 (Real analysis, complex analysis, and functional analysis)
Birth date:
8.05.1940
Keywords:
precision of approximation of functions; trigonometrical Fourier series; restoration of functions by values in points; series summation; extremal problems of approximation theory; linear methods of approximation; inequalities for derivatives; formulas of numerical differentiation; moduli of continuity; strong approximation of functions.
Subject:
Scientific interests are connected with approximation theory, Fourier series and their applications. General theorems which allow to get both-sided estimates for deviation of the wide class of approximation methods in the terms of moduli of continuity are established. These estimates coincide if one doesn"t take constants into account and are sharp in the order sense for each individual function. The techniqie of obtaining the estimates of approximation methods by moduli of continuity of arbitrary order of functions defined on the line or on the segment is developed. The constants in these estimates are greatly more sharp in comparison with the constants which were known earlier. Several difficult extremal problems are solved. These problems deal with finding of sharp constants in direct theorems of approximation theory (Jackson-type inequalities) and inequalities for derivatives (Landau–Kolmogorov-type inequalities). These problems were studied in connection with each other for the first time. Some "latent" orthogonalities connecting important for approximation theory objects are discovered. The analogs of Parseval equality are established and their applications to different problems, especially to the strong approximation, are given. Strictly mathematically justified, simple and effective algorithms of rectoration of function of several variables by its values in given points are constructed. New results concerning convergence of ordinary and multiple Fourier series are obtained. In 1999&ndash2001 the series of papers (jointly with O. L. Vinogradov) was published. These papers deal with extremal problems of approximation theory which lend themselves to solving very slowly.
Biography
Graduated from Faculty of Mathematics and Mechanics of Leningrad State University in 1962 (department of mathematical analysis). D.Sci. thesis was defended in 1994. A list of my works contain more than 140 titles.
Main publications:
Zhuk V. V. Approksimatsiya periodicheskikh funktsii. Leningrad, 1982. 366 s.
Zhuk V. V. Silnaya approksimatsiya periodicheskikh funktsii. Leningrad, 1989. 296 s.
Zhuk V. V., Kuzyutin V. F. Approksimatsiya funktsii i chislennoe integrirovanie. S.-Peterburg, 1995. 352 s.
Vinogradov O. L., Zhuk V. V. Tochnye otsenki pogreshnostei formul tipa chislennogo differentsirovaniya na trigonometricheskikh mnogochlenakh // Problemy matematicheskogo analiza. Vypusk 21. 2000. S. 68–109.
Vinogradov O. L., Zhuk V. V. Tochnye neravenstva tipa Dzheksona dlya differentsiruemykh funktsii i minimizatsiya shaga modulya nepreryvnosti // Trudy S.-Peterburgskogo matematicheskogo obschestva. T. 8. 2000. S. 29–51.
M. V. Babushkin, V. V. Zhuk, “On a strong form of asymptotic formulas of Voronovskaya–Bernstein type with pointwise estimate of the remainder term”, Zap. Nauchn. Sem. POMI, 449 (2016), 32–59; J. Math. Sci. (N. Y.), 225:6 (2017), 859–876
M. V. Babushkin, V. V. Zhuk, “On two-sided estimates for some functionals in terms of the best approximations”, Zap. Nauchn. Sem. POMI, 449 (2016), 15–31; J. Math. Sci. (N. Y.), 225:6 (2017), 848–858
M. V. Babushkin, V. V. Zhuk, “Growth of norms in $L_2$ of derivatives of Steklov functions and properties of functions defined by best approximations and Fourier coefficients”, Zap. Nauchn. Sem. POMI, 445 (2016), 5–32; J. Math. Sci. (N. Y.), 222:5 (2017), 525–543
2015
4.
V. V. Zhuk, O. A. Tumka, N. A. Kozlov, “Constants in Jackson-type inequations for the best approximation of periodic differentiable functions”, Vestnik S.-Petersburg Univ. Ser. 10. Prikl. Mat. Inform. Prots. Upr., 2015, no. 1, 33–41
V. V. Zhuk, “On strong approximation of functions by positive operators”, Zap. Nauchn. Sem. POMI, 440 (2015), 68–80; J. Math. Sci. (N. Y.), 217:1 (2016), 45–53
V. V. Zhuk, O. A. Tumka, “On some modifications of Jackson's generalized theorem for the best approximations of periodic functions”, Vestnik S.-Petersburg Univ. Ser. 10. Prikl. Mat. Inform. Prots. Upr., 2014, no. 1, 40–50
V. V. Zhuk, G. Yu. Puerov, “Some inequalities for trigonometric polynomials and Fourier coefficients”, Zap. Nauchn. Sem. POMI, 429 (2014), 64–81; J. Math. Sci. (N. Y.), 207:6 (2015), 845–856
V. O. Dron, V. V. Zhuk, “On approximation of periodic functions by modified Steklov averages in $L_2$”, Zap. Nauchn. Sem. POMI, 429 (2014), 20–33; J. Math. Sci. (N. Y.), 207:6 (2015), 815–824
2013
9.
O. L. Vinogradov, V. V. Zhuk, “Estimates for functionals with a known finite set of moments in terms of high order moduli of continuity in the spaces of functions defined on the segment”, Algebra i Analiz, 25:3 (2013), 86–120; St. Petersburg Math. J., 25:3 (2014), 421–446
M. V. Babushkin, V. V. Zhuk, “On the constants in inequalities of the generalized Jackson theorem type”, Zap. Nauchn. Sem. POMI, 418 (2013), 28–59; J. Math. Sci. (N. Y.), 200:5 (2014), 532–550
11.
O. L. Vinogradov, V. V. Zhuk, “Estimates of functionals by the second moduli of continuity of even derivatives”, Zap. Nauchn. Sem. POMI, 416 (2013), 70–90; J. Math. Sci. (N. Y.), 202:4 (2014), 526–540
O. L. Vinogradov, V. V. Zhuk, “Estimates for functional with a known finite set of moments in terms of moduli of continuity and behaviour of constants in the Jackson-type inequalities”, Algebra i Analiz, 24:5 (2012), 1–43; St. Petersburg Math. J., 24:5 (2013), 691–721
V. V. Zhuk, “Estimates of best approximations of periodic function by linear combinations values of the function itself and its primitives”, Zap. Nauchn. Sem. POMI, 404 (2012), 157–174; J. Math. Sci. (N. Y.), 193:1 (2013), 89–99
V. V. Zhuk, “Inequalities of type generalized Jackson theorem for best approximations”, Zap. Nauchn. Sem. POMI, 404 (2012), 135–156; J. Math. Sci. (N. Y.), 193:1 (2013), 75–88
O. L. Vinogradov, V. V. Zhuk, “Estimates for functionals with a known finite set of moments in terms of deviations of operators constructed with the use of the Steklov averages and finite differences”, Zap. Nauchn. Sem. POMI, 392 (2011), 32–66; J. Math. Sci. (N. Y.), 184:6 (2012), 679–698
David W. K. Yeung, Leon Petrosyan, Vladimir Zhuk, Anna V. Iljina, “The Detalization of the Irrational Behavior Proof Condition”, Contributions to Game Theory and Management, 3 (2010), 431–440
17.
O. L. Vinogradov, V. V. Zhuk, “The rate of decrease of constants in Jackson type inequalities in dependence of the order of modulus of continuity”, Zap. Nauchn. Sem. POMI, 383 (2010), 33–52
O. L. Vinogradov, V. V. Zhuk, “Estimates for functionals with a known moment sequence in terms of deviations of Steklov type means”, Zap. Nauchn. Sem. POMI, 383 (2010), 5–32; J. Math. Sci. (N. Y.), 178:2 (2011), 115–131
V. V. Zhuk, “On approximating periodic functions by the Fourier sums”, Zap. Nauchn. Sem. POMI, 371 (2009), 78–108; J. Math. Sci. (N. Y.), 166:2 (2010), 167–185
20.
N. Yu. Dodonov, V. V. Zhuk, “On approximating periodic functions by Riesz sums”, Zap. Nauchn. Sem. POMI, 371 (2009), 18–36; J. Math. Sci. (N. Y.), 166:2 (2010), 134–144
2008
21.
V. V. Zhuk, “Approximation of periodic functions in the uniform metric by Jackson type polynomials”, Zap. Nauchn. Sem. POMI, 357 (2008), 115–142; J. Math. Sci. (N. Y.), 157:4 (2009), 607–622
22.
V. V. Zhuk, “Approximation of periodic functions by Jackson type interpolation sums”, Zap. Nauchn. Sem. POMI, 357 (2008), 90–114; J. Math. Sci. (N. Y.), 157:4 (2009), 592–606
2007
23.
V. V. Zhuk, “Approximating periodic functions in Hölder type metrics by the Fourier sums and the Riesz means”, Zap. Nauchn. Sem. POMI, 350 (2007), 70–88; J. Math. Sci. (N. Y.), 150:3 (2008), 2045–2055
A. S. Zhuk, V. V. Zhuk, “On approximating periodic functions using linear approximation methods”, Zap. Nauchn. Sem. POMI, 337 (2006), 134–164; J. Math. Sci. (N. Y.), 143:3 (2007), 3090–3107
N. Yu. Dodonov, V. V. Zhuk, “On approximating periodic functions by singular integrals with positive kernels”, Zap. Nauchn. Sem. POMI, 337 (2006), 51–72; J. Math. Sci. (N. Y.), 143:3 (2007), 3039–3052
2004
26.
A. S. Zhuk, V. V. Zhuk, “Some orthogonalities in approximation theory”, Zap. Nauchn. Sem. POMI, 314 (2004), 83–123; J. Math. Sci. (N. Y.), 133:6 (2006), 1652–1675
O. L. Vinogradov, V. V. Zhuk, “Sharp Kolmogorov-type inequalities for moduli of continuity and best approximations by trigonometric polynomials and splines”, Zap. Nauchn. Sem. POMI, 290 (2002), 5–26; J. Math. Sci. (N. Y.), 124:2 (2004), 4845–4857
V. V. Zhuk, G. I. Natanson, “Semi-norms and continuity modules of functions defined on a segment”, Zap. Nauchn. Sem. POMI, 276 (2001), 155–203; J. Math. Sci. (N. Y.), 118:1 (2003), 4822–4851
V. V. Zhuk, O. L. Vinogradov, “Parseval-type inequalities and some of their applications”, Dokl. Akad. Nauk, 341:6 (1995), 737–739
1992
30.
V. V. Zhuk, “On the convergence of the Fourier trigonometric series at a point”, Dokl. Akad. Nauk, 326:5 (1992), 770–775; Dokl. Math., 46:2 (1993), 349–353
31.
V. V. Zhuk, G. I. Natanson, “Approximation of functions on standard simplexes”, Dokl. Akad. Nauk, 324:4 (1992), 734–737; Dokl. Math., 45:3 (1992), 614–618
V. V. Zhuk, “Certain exact bounds for seminorms given on spaces of periodic functions”, Mat. Zametki, 21:6 (1977), 789–798; Math. Notes, 21:6 (1977), 445–450
V. V. Zhuk, “Some exact inequalities between the best approximations and moduli of continuity of high orders”, Mat. Zametki, 21:2 (1977), 281–288; Math. Notes, 21:2 (1977), 153–157
1974
34.
V. V. Zhuk, “Some sharp inequalities for uniform best approximations of periodic functions”, Dokl. Akad. Nauk SSSR, 214:6 (1974), 1245–1246
1973
35.
V. V. Zhuk, G. I. Natanson, “Properties of functions, and growth of the derivatives of the approximating polynomials”, Dokl. Akad. Nauk SSSR, 212:1 (1973), 19–22
V. V. Zhuk, “Certain sharp inequalities between best approximations”, Izv. Vyssh. Uchebn. Zaved. Mat., 1973, no. 1, 51–56
1972
38.
V. V. Zhuk, “The accuracy of the representation of a continuous $2\pi$-periodic function by means of linear approximation methods”, Izv. Vyssh. Uchebn. Zaved. Mat., 1972, no. 8, 46–59
V. V. Zhuk, “Certain exact inequalities between best approximations and moduli of continuity”, Sibirsk. Mat. Zh., 12:6 (1971), 1283–1291; Siberian Math. J., 12:6 (1971), 924–930
V. V. Zhuk, “The rate of approximation of a continuous $2\pi$-periodic function by partial sums of its Fourier series”, Dokl. Akad. Nauk SSSR, 190:5 (1970), 1015–1018
V. V. Zhuk, “Some relations between moduli of continuity and functionals defined on sets of periodic functions”, Izv. Vyssh. Uchebn. Zaved. Mat., 1970, no. 5, 24–33
1969
44.
V. V. Zhuk, “The order of approximation of a continuous $2\pi$-periodic function by linear methods”, Izv. Vyssh. Uchebn. Zaved. Mat., 1969, no. 10, 40–50
45.
V. V. Zhuk, G. I. Natanson, “Saturation theory converse problem”, Mat. Zametki, 6:5 (1969), 583–590; Math. Notes, 6:5 (1969), 811–815
V. V. Zhuk, “The approximation of periodic functions by linear approximation methods”, Dokl. Akad. Nauk SSSR, 179:5 (1968), 1038–1041
47.
V. V. Zhuk, “On the order of approximation of a continuous $2\pi$-periodic function by Fejer and Poisson means of its Fourier series”, Mat. Zametki, 4:1 (1968), 21–32; Math. Notes, 4:1 (1968), 500–508
V. V. Zhuk, “The question of approximating periodic functions by linear summation methods for Fourier series”, Sibirsk. Mat. Zh., 9:3 (1968), 713–716; Siberian Math. J., 9:3 (1968), 534–536
V. V. Zhuk, “Approximation of periodic functions by linear methods of summation of Fourier series”, Dokl. Akad. Nauk SSSR, 173:1 (1967), 30–33
1966
50.
V. V. Zhuk, “Approximation of periodic functions bounded by a subadditive operator”, Dokl. Akad. Nauk SSSR, 169:3 (1966), 515–518
1965
51.
V. V. Zhuk, “Some modifications of the concept of modulus of smoothness and their applications”, Dokl. Akad. Nauk SSSR, 162:1 (1965), 19–22
52.
V. V. Zhuk, “A modification of the concept of modulus of smoothness and its application to the estimation of Fourier coefficients”, Dokl. Akad. Nauk SSSR, 160:4 (1965), 758–761
53.
V. V. Zhuk, “On the absolute convergence of Fourier series”, Dokl. Akad. Nauk SSSR, 160:3 (1965), 519–522
2004
54.
V. M. Babich, A. M. Vershik, V. S. Videnskii, O. L. Vinogradov, I. K. Daugavet, N. Yu. Dodonov, V. V. Zhuk, B. M. Makarov, A. N. Podkorutov, Yu. G. Reshetnyak, M. A. Skopina, V. L. Fainshmidt, V. P. Havin, N. A. Shirokov, “Garal'd Isidorovich Natanson (obituary)”, Uspekhi Mat. Nauk, 59:4(358) (2004), 181–185; Russian Math. Surveys, 59:4 (2004), 771–776
2002
55.
V. V. Zhuk, V. N. Malozemov, G. I. Natanson, V. P. Havin, “Viktor Solomonovich Videnskii (on his 80th birthday)”, Uspekhi Mat. Nauk, 57:5(347) (2002), 182–186; Russian Math. Surveys, 57:5 (2002), 1033–1038
2001
56.
E. G. Goluzina, V. V. Zhuk, G. V. Kuz'mina, N. A. Shirokov, “Nikolai Andreevich Lebedev and the Leningrad school of function theory in the 1950–1970s”, Zap. Nauchn. Sem. POMI, 276 (2001), 5–19; J. Math. Sci. (N. Y.), 118:1 (2003), 4733–4739