Борислав Радков Драганов

Борислав Радков Драганов

Доцент
Доктор

Математически анализ

Имейл: 
bdraganov(at)fmi.uni-sofia.bg
Телефон: 
02/8161-766
Кабинет: 
ФМИ-211
Приемно време: 

във ФМИ - по предварителна уговорка

по Skype: Skype name: bdraganov_1

Образование и научни степени

  • 2024: доктор на науките, СУ "Св. Кл. Охридски", ФМИ
  • 2004: доктор, СУ "Св. Кл. Охридски", ФМИ
  • 1998: магистър специалност математика, СУ "Св. Кл. Охридски", ФМИ
  • 1993: Първа английска езикова гимназия, гр. София

Научни интереси

  • Теория на апроксимациите
  • Функционален анализ
  • Хармоничен анализ

Преподавателска дейност

Списък с публикации

    1. A new modulus of smoothness for trigonometric polynomial approximation, East J. Approx. 8 (2002), 4, 465-499 (pdf).
    2. A new modulus of smoothness for trigonometric polynomial approximation,  Constructive Theory of Functions, Varna, 2002. Proc. Ed. B. Bojanov, Darba, Sofia, 2003, 245-250 (pdf).
    3. The trigonometric analogue of the Taylor's formula and its application, Annuaire Univ. Sofia Fac. Math. Inform. 96 (2004), 141-154 (pdf).
    4. (with Kamen G. Ivanov) A new characterization of weighted Peetre K-functionals, Constr. Approx. 21 (2005), 113-148 (pdf, original publication available at Springer http://www.springerlink.com/).
    5. (with Kamen G. Ivanov) A Characterization of Weighted Lp Approximations by the Gamma and the Post-Widder Operators, Proc. intern. conf. "Constructive Theory of Functions, Varna 2005'', Ed. B. Bojanov, Marin Drinov Academic Publishing House, Sofia, 2006, 80-87 (pdf).
    6. (with Kamen G. Ivanov) Characterizations of Weighted K-Functionals and Their Application, Proc. intern. conf. "Constructive Theory of Functions, Varna 2005'', Ed. B. Bojanov, Marin Drinov Academic Publishing House, Sofia, 2006, 88-97 (pdf).
    7. (with Kamen G. Ivanov) A new characterization of weighted Peetre K-functionals (II), Serdica Math. J. 33 (2007), 59-124 (pdf).
    8. (with Kamen G. Ivanov) A characterization of weighted approximations by the Post-Widder and the Gamma operators, J. Approx. Theory 146 (2007), 3-27 (preprint, original publication available at Elsevier).
    9. (with Kamen G. Ivanov) Equivalence between K-functionals based on continuous linear transforms, Serdica Math. J. 33 (2007), 475-494 (pdf).
    10. Simultaneous approximation of functions by Fejér-type operators in a generalized Hölder norm, East J. Approx. 14 (2008), 439-449 (pdf).
    11. Exact estimates of the rate of approximation of convolution operators, J. Approx. Theory 162 (2010), 952-979 (preprint, original publication available at Elsevier).
    12. (with Kamen G. Ivanov) A Characterization of Weighted Approximations by the Post-Widder and the Gamma Operators (II), J. Approx. Theory 162 (2010), 1805-1851 (preprint, original publication available at Elsevier).
    13. On the approximation by convolution operators in homogeneous Banach spaces of periodic functions, Math. Balkanica 25 (2011), 39-59 (pdf).
    14. (with Parvan E. Parvanov) On estimating the rate of best trigonometric approximation by a modulus of smoothness, Acta Math. Hungar. 131 (2011),  360-379 (pdf, original publication available at Springer http://www.springerlink.com, read-only pdf at Springer Nature SharedIt).
    15. Estimating the rate of best trigonometric approximation in homogeneous Banach spaces by moduli of smoothness, Proc. intern. conf. "Constructive Theory of Functions", Sozopol 2010: In Memory of Borislav Bojanov, Eds. G. Nikolov and R. Uluchev, Marin Drinov Academic Publishing House, Sofia, 2012, 80-92 (pdf). 

    16. An improved Jackson inequality for best trigonometric approximation, Ukr. Mat. Zhurn. 65 (2013), 1219-1226 and Ukrainian Math. J. 65 (2014), 1354-1362 (pdf, final publication available at link.springer.com); a preprint: A sharp Jackson inequality for best trigonometric approximation, CRM Preprint Series 1101, 2012 (available at CRM).

    17. Upper estimates of the approximation rate of combinations of iterates of the Bernstein operator, Annuaire Univ. Sofia Fac. Math. Inform. 101 (2013), 95-104 (pdf).
    18. (with Kamen G. Ivanov) A generalized modulus of smoothness, Proc. Amer. Math. Soc. 142 (2014), 1577-1590.  
    19. On simultaneous approximation by iterated Boolean sums of Bernstein operators, Results Math. 66 (2014), 21-41 (read-only pdf at Springer Nature SharedIt, pdf, final publication available at link.springer.com). 
    20. (with Kamen G. Ivanov) Natural weights for uniform approximation by the Szasz-Mirakjan operator,  Proc. intern. conf. "Constructive Theory of Functions", Sozopol 2013: Dedicated to Blagovest Sendov and to the memory of Vasil Popov, Eds. Kamen Ivanov, Geno Nikolov and Rumen Uluchev, Prof. Marin Drinov Academic Publishing House, Sofia, 2014, 57-82 (pdf).
    21. On the approximation by convolution operators in homogeneous Banach spaces on Rd, Math. Balkanica 28 (2014), 9-36 (pdf).
    22. Strong estimates of the weighted simultaneous approximation by the Bernstein and Kantorovich operators and their iterated Boolean sums, J. Approx. Theory 200 (2015), 92–135; 252 (2020) 105321 (accepted&corrected manuscript, original publication available at Elsevier).
    23. (with Ivan Gadjev) Direct and converse Voronovskaya estimates for the Bernstein operator, Results Math. 73:11 (2018) (read-only pdf at Springer Nature SharedIt, final publication available at link.springer.com).
    24. An exact strong converse inequality for the weighted simultaneous approximation by the Bernstein operator, Proc. intern. conf. "Constructive Theory of Functions", Sozopol 2016, Eds. Kamen Ivanov, Geno Nikolov and Rumen Uluchev, Prof. Marin Drinov Academic Publishing House, Sofia, 2018, 75-97 (pdf).
    25. (with Kamen G. Ivanov) A New Characterization of Weighted Peetre K-Functionals (III), Proc. intern. conf. "Constructive Theory of Functions", Sozopol 2016, Eds. Kamen Ivanov, Geno Nikolov and Rumen Uluchev, Prof. Marin Drinov Academic Publishing House, Sofia, 2018, 99-141 (pdf).
    26. Strong converse inequalities for the weighted multivariate Bernstein-Durrmeyer operator on the simplex via multipliers, Ann. Sofia Univ., Fac. Math and Inf. 105 (2018), 55–73 (pdf).
    27. Simultaneous approximation by Bernstein polynomials with integer coefficients, J. Approx. Theory 237 (2019), 1-16 (accepted manuscript, original publication available at Elsevier).
    28. (with I. Gadjev) Approximation of functions by the Szasz-Mirakjan-Kantorovich Operator, Numer. Funct. Anal. Optim. 40 (2019), 803–824, e-prints. 
    29. Shape preserving properties of the Bernstein polynomials with integer coefficients, Ann. Sofia Univ., Fac. Math and Inf. 109 (2019), 79–100, (pdf).
    30. Converse estimates for the simultaneous approximation by Bernstein polynomials with integer coefficients, Proc. intern. conf. "Constructive Theory of Functions", Sozopol 2019, Eds. Borislav Draganov, Kamen Ivanov, Geno Nikolov and Rumen Uluchev, Prof. Marin Drinov Academic Publishing House, Sofia, 2020, 39-51, pdf, arXiv:1904.09417. 
    31. Direct estimates of the weighted simultaneous approximation by the Baskakov operator, Results Math. 75, 156 (2020) (read-only pdf at Springer Nature SharedIt).
    32. Strong converse inequalities for the weighted simultaneous approximation by the Szasz-Mirakjan operator, Serdica Math. J. 46 (2020), 261–286, pdf.
    33. Direct estimates of the weighted simultaneous approximation by the Szasz-Mirakjan operator, Period. Math. Hungar. 83 (2021), 88-109 (read-only pdf at Springer Nature SharedIt).
    34. (with Tuncer Acar) A strong converse inequality for generalized sampling operators, Ann. Funct. Anal. 13:36 (2022) (read-only pdf at Springer Nature SharedIt, accepted manuscript with minor corrections, original publication available at Springer Link).
    35. A strong converse inequality for the iterated Boolean sums of the Bernstein operator, Stud. Univ. Babes-Bolyai Math. 67 (2022), No. 3, 591–598, pdf.
    36. A fast converging sampling operator, Constr. Math. Anal. 5 (2022), No. 4, 190-201, pdf.
    37. Voronovskaya estimates for convolution operators, Dolomites Res. Notes Approx. 16 (2023), 38-51, pdf.
    38. (with Tuncer Acar) A characterization of the rate of the simultaneous approximation by generalized sampling operators and their Kantorovich modification, J. Math. Anal. Appl. 530 (2024), 127740.
    39. A characterization of the rate of approximation of Kantorovich sampling operators in variable exponent Lebesgue spaces, Rev. Real Acad. Cienc. Exactas Fis. Nat. Ser. A-Mat. 118 (2024), 71 (a read-only pdf at Springer Nature SharedIt).
    40. (with I. Gadjev) Direct estimates of the rate of approximation by the Kantorovich operator in variable exponent Lebesgue spaces, Mediterr. J. Math. 21 (2024), 112 (a read-only pdf at Springer Nature SharedIt).
    41. Weighted simultaneous approximation by Kantorovich sampling operators, Proc. intern. conf. "Constructive Theory of Functions", Lozenets 2023, Eds. Borislav Draganov, Kamen Ivanov, Geno Nikolov and Rumen Uluchev, Prof. Marin Drinov Academic Publishing House, Sofia, 2024, 17-41, pdf.
    42. (with I. Gadjev) A strong converse estimate of the rate of approximation by the Kantorovich operator in variable exponent Lebesgue spaces, Boll. Unione Mat. Ital. (2024), https://doi.org/10.1007/s40574-024-00430-x (a read-only pdf at Springer Nature SharedIt).

© Факултет по Математика и Информатика