Dr. Oktay Duman

Research

(Last updated: June 23, 2025)

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Publications:

  1. O. Duman, Improved approximation via hybrid Shepard-Lagrange operators: Linear and nonlinear perspectives, J. Comput. Appl. Math. (2025), accepted for publication.
  2. O. Duman, Faster approximation to multivariate functions by combined Bernstein-Taylor operators, Demonstratio Math. 58 (2025), no. 1, Article No. 20250129, 11 pp.
  3. O. Duman and E. Erkus-Duman, Nonlinear approximation of vector-valued functions by Shepard operators based on max-product and max-min operations, Fuzzy Sets Systems 509 (2025), Paper No. 109332, 14 pp.
  4. M. E. Alemdar and O. Duman, Asymptotic formulae for modified Bernstein operators based on regular summability methods, Hacettepe J. Math. Stat. 54 (2025), no. 3, 958-971.
  5. O. Duman, B. Della Vecchia and E. Erkus-Duman, Kantorovich version of vector-valued Shepard operators, Axioms 13 (2024), Paper No. 181, 12 pp.
  6. O. Duman, Max-product Shepard operators based on multivariable Taylor polynomials, J. Comput. Appl. Math. 437 (2024), Paper No. 115456, 15 pp.
  7. O. Duman and B. Della Vecchia, Vector-valued Shepard processes: Approximation with summability, Axioms, 12 (2023), Paper No. 1124, 16 pp.
  8. C. Turan Yalçın and O. Duman, Regular integral transformations on time scales and generalized statistical convergence, Filomat 37 (2023), no. 12, 4017-4028.
  9. O. Duman and B. Della Vecchia, Approximation to integrable functions by modified complex Shepard operators, J. Math. Anal. Appl. 512 (2022), no. 2, Paper No. 126161, 13 pp.
  10. T. Y. Gökçer and O. Duman, Regular summability methods in the approximation by max-min operators, Fuzzy Sets Systems 426 (2022), 106-120.
  11. O. Duman and B. Della Vecchia, Complex Shepard operators and their summability, Results Math. 76 (2021), no. 4, Paper No. 214, 19 pp.
  12. M. E. Alemdar and O. Duman, General summability methods in the approximation by Bernstein-Chlodovsky operators, Numer. Funct. Anal. Optim. 42 (2021), no. 5, 497-509.
  13. İ. Aslan and O. Duman, Nonlinear approximation in \(n\)-dimension with the help of summability methods, Rev. R. Acad. Cienc. Exactas Fis. Nat. Ser. A Mat. RACSAM 115 (2021), no. 3, paper no. 105, 27 pp.
  14. O. Duman, Generalized Cesaro summability of Fourier series and its applications, Constr. Math. Anal. 4 (2021), no. 2, 135-144.
  15. İ. Aslan and O. Duman, Characterization of absolute and uniform continuity, Hacettepe J. Math. Stat. 49 (2020), no. 5, 1550-1565.
  16. O. Ocalan and O. Duman, Solutions to conjectures on a nonlinear recursive equation, Czechoslovak Math. J. 70 (2020), no. 3, 867-880.
  17. T. Y. Gökçer and O. Duman, Approximation by max-min operators: A general theory and its applications, Fuzzy Sets Systems, 394 (2020), 146-161.
  18. C. Turkun and O. Duman, Modified neural network operators and their convergence properties with summability methods, Rev. R. Acad. Cienc. Exactas Fis. Nat. Ser. A Mat. RACSAM 114 (2020), no. 3, paper no. 132, 18 pp.
  19. İ. Aslan and O. Duman, Approximation by nonlinear operators via summability process, Math. Nachr. 293 (2020), no. 3, 430-448.
  20. [Book Chapter] O. Duman, Error estimation for approximate solutions of delay Volterra integral equations, in "Frontiers in Functional Equations and Analytic Inequalities", pp. 585-597, Springer Nature, Switzerland, 2019.
  21. İ. Aslan and O. Duman, Summability on Mellin-type nonlinear integral operators, Integral Transforms Spec. Funct. 30 (2019), no. 6, 492-511.
  22. O. Ocalan and O. Duman, On solutions of the recursive equations \( x_{n+1}=x_{n-1}^{p}/x_{n}^{p}\,\, (p>0) \) via Fibonacci-type sequences, Electron. J. Math. Anal. Appl. 7 (2019), no. 1, 102-115.
  23. C. Turan Yalçın and O. Duman, Hardy-type Tauberian conditions on time scales, Mediterr. J. Math. 15 (2018), no. 5, paper no. 198, 12 pp.
  24. C. Turan and O. Duman, Fundamental properties of statistical convergence and lacunary statistical convergence on time scales, Filomat, 31 (2017), no. 14, 4455-4467.
  25. O. G. Atlihan, M. Unver and O. Duman, Korovkin theorems on weighted spaces: revisited, Periodica Math. Hungar. 75 (2017), no. 2, 201-209.
  26. O. Duman, Singular approximation in polydiscs by summability process, Positivity 20 (2016), no. 3, 663-676.
  27. [Book Chapter] T. Y. Gökçer and O. Duman, Summation process by max-product operators, in "Computational Analysis", pp. 59-67, Springer Proceedings in Mathematics & Statistics, Springer, New York, 2016.
  28. [Edited Book] G. A. Anastassiou and O. Duman (eds.), Computational Analysis, Springer Proceedings in Mathematics & Statistics, Springer, New York, 2016, 396 pp. ISBN 978-3-319-28441-5.
  29. İ. Aslan and O. Duman, Summability process on the Baskakov-type approximation, Periodica Math. Hungar. 72 (2016), no. 2, 186-199.
  30. [Book Chapter] O. Duman, Nonlinear approximation: \(q\)-Bernstein operators of max-product kind, in "Intelligent Mathematics II: Applied Mathematics and Approximation Theory", pp. 33-56, Advances in Intelligent Systems and Computing, Vol. 441, Springer, Heidelberg, 2016.
  31. [Edited Book] G. A. Anastassiou and O. Duman (eds.), Intelligent Mathematics II: Applied Mathematics and Approximation Theory, Advances in Intelligent Systems and Computing, Vol. 441, Springer, Heidelberg, 2016, 502 pp. ISBN 978-3-319-30322-2.
  32. M. A. Özarslan and O. Duman, Smoothness properties of modified Bernstein-Kantorovich operators, Numer. Funct. Anal. Optim. 37 (2016), no. 1, 92-105.
  33. N. Küçük and O. Duman, Summability methods in weighted approximation to derivatives of functions, Serdica Math. J. 41 (2015), no. 4, 355-368.
  34. O. Duman, Summability process by Mastroianni operators and their generalizations, Mediterr. J. Math. 12 (2015), no. 1, 21-35.
  35. O. Duman, Nonlinear Bernstein-type operators providing a better error estimation, Miskolc. Math. Notes 15 (2014), no. 2, 393-400.
  36. O. Duman, Summability process by singular operators, Publ. Math. Debrecen 85 (2014), no. 3-4, 373-386.
  37. [Edited Book] G. A. Anastassiou and O. Duman (eds.), Advances in Applied Mathematics and Approximation Theory, Springer Proceedings in Mathematics & Statistics, Vol. 41, Springer, New York, 2013, 486 pp. ISBN: 978-1-4614-6393-1.
  38. C. Turan and O. Duman, Convergence methods on time scales, AIP Conf. Proc. 1558 (2013) 1120-1123.
  39. [Book Chapter] C. Turan and O. Duman, Statistical convergence on time scales and its characterizations, in "Advances in Applied Mathematics and Approximation Theory", pp. 57-71, Springer Proc. Math. Stat., vol. 41, Springer, New York, 2013.
  40. A. A. Ergür and O. Duman, Generalization of statistical Korovkin theorems, J. Appl. Math. 2013, Article ID 187530, 5 pp.
  41. Z. Ünal, M. A. Özarslan and O. Duman, Approximation properties of real and complex Post-Widder operators based on \(q\)-integers, Miskolc. Math. Notes 13 (2012), no. 2, 581-603.
  42. O. Duman and M. Kester, Statistical approximation by double Poisson-Cauchy singular integral operators, Results Math. 62 (2012), no. 1-2, 53-65.
  43. A. D. Gadjiev, O. Duman and A. M. Ghorbanalizadeh, Ideal convergence of k-positive linear operators, J. Funct. Spaces Appl. 2012, Article ID 178316, 12 pp.
  44. [Monograph Book] G. A. Anastassiou and O. Duman, Towards Intelligent Modeling: Statistical Approximation Theory, Intelligent Systems Reference Library, Vol. 14, Springer, Berlin, 2011, 234 pp. ISBN: 978-3-642-19825-0.
  45. O. Duman and E. Erkuş-Duman, Statistical Korovkin-type theory for matrix-valued functions, Studia Sci. Math. Hungar. 48 (2011) 489-508.
  46. H. Aktuğlu, M. A. Özarslan and O. Duman, Matrix summability methods on the approximation of multivatiate \(q\)-MKZ operators, Bull. Malaysian Math. Sci. Soc. 34 (2011) 465-474.
  47. A. Aral and O. Duman, A Voronovskaya-type formula for SMK operators via statistical convergence, Math. Slovaca 61 (2011) 235-244.
  48. M. Burgin and O. Duman, Approximations by linear operators in spaces of fuzzy continuous functions, Positivity 15 (2011) 57-72.
  49. M. A. Özarslan, O. Duman and N.I. Mahmudov, Local approximation properties of modified Baskakov operators, Results Math. 59 (2011) 1-11.
  50. G. A. Anastassiou and O. Duman, Statistical \(L_p\)-convergence of double smooth Picard singular integral operators, J. Comput. Anal. Appl. 13 (2011) 167-187.
  51. O. Duman and M. A. Özarslan, Global approximation results for modified Szasz-Mirakjan operators, Taiwanese J. Math. 15 (2011) 75-86.
  52. G. A. Anastassiou and O. Duman, Statistical approximation by double complex Gauss-Weierstrass integral operators, Appl. Math. Lett. 24 (2011) 438-443.
  53. E. Erkuş-Duman and O. Duman, Statistical approximation properties of high order operators constructed with the Chan-Chyan-Srivastava polynomials, Appl. Math. Comput. 218 (2011) 1927-1933.
  54. M. Burgin and O. Duman, Approximate fuzzy continuity of functions, Internat. J. Fuzzy Syst. Appl. 1 (2011) 37-46.
  55. O. Duman, Statistical fuzzy approximation to fuzzy differentiable functions by fuzzy linear operators, Hacettepe J. Math. Stat. 39 (2010) 497-514.
  56. M. A. Özarslan and O. Duman, Local approximation behavior of modified SMK operators, Miskolc Math. Notes 11 (2010) 87-99.
  57. O. Duman, Statistical convergence of max-product approximating operators, Turkish J. Math. 34 (2010) 501-514.
  58. F. Dirik, O. Duman and K. Demirci, Approximation in statistical sense to B-continuous functions by positive linear operators, Studia Sci. Math. Hungar. 47 (2010) 289-298.
  59. M. A. Özarslan and O. Duman, Global approximation properties of modified SMK operators, Filomat 24 (2010) 47-61.
  60. S. Karakuş, K. Demirci and O. Duman, Statistical approximation by positive linear operators on modular spaces, Positivity 14 (2010) 312-334.
  61. G. A. Anastassiou and O. Duman, Statistical convergence of double complex Picard integral operators, Appl. Math. Lett. 23 (2010) 852-858.
  62. M. A. Özarslan, O. Duman and C. Kaanoğlu, Rates of convergence of certain King-type operators for functions with derivative of bounded variation, Math. Comput. Modelling 52 (2010) 334-345.
  63. G. A. Anastassiou and O. Duman, Statistical Korovkin theory for multivariate stochastic processes, Stoch. Anal. Appl. 28 (2010) 648-661.
  64. O. Duman, Fuzzy approximation based on statistical rates, Publ. Math. Debrecen 76 (2010) 453-463.
  65. G. A. Anastassiou and O. Duman, Statistical \(L_p\) approximation by double Gauss-Weierstrass singular integral operators, Comput. Math. Appl. 59 (2010) 1985-1999.
  66. O. Duman, M. A. Özarslan and E. Erkuş-Duman, Rates of ideal convergence for approximation operators, Mediterr. J. Math. 7 (2010) 111-121.
  67. O. Duman and M. Gürcan, Some characterizations on statistical convergence of expected values of random variables, J. Math. Anal. 1 (2010) 1-8.
  68. G. A. Anastassiou and O. Duman, Uniform approximation in statistical sense by double Gauss-Weierstrass singular integral operators, Nonlinear Funct. Anal. Appl. 15 (2010) 487-502.
  69. V. Gupta and O. Duman, Bernstein-Durrmeyer type operators preserving linear functions, Mat. Vesnik 62 (2010) 259-264.
  70. G. A. Anastassiou and O. Duman, Fractional trigonometric Korovkin theory in statistical sense, Serdica Math. J. 36 (2010) 121-136.
  71. M. Bohner and O. Duman, Opial-type inequalities for diamond-alpha derivatives and integrals on time scales, Differ. Equ. Dyn. Syst. 18 (2010) 229-237.
  72. G. A. Anastassiou and O. Duman, Statistical approximation by double Picard singular integral operators, Studia Univ. Babes-Bolyai Math. 55 (2010), 3-20.
  73. M. Burgin and O. Duman, Fuzzy approximate continuity, J. Intell. Fuzzy Systems 20 (2009) 225-233.
  74. O. Duman, Strong versions of the theorems of Weierstrass, Montel and Hurwitz, Hacettepe J. Math. Stat. 38 (2009) 153-159.
  75. F. Dirik, O. Duman and K. Demirci, Statistical approximation to Bögel-type continuous and periodic functions, Cent. Eur. J. Math. 7 (2009) 539-549.
  76. O. Duman and H. Merdan, Stability analysis of continuous population model involving predation and Allee effect, Chaos Solitons Fractals 41 (2009) 1218-1222.
  77. M. A. Özarslan and O. Duman, Approximation theorems by Meyer-König and Zeller type operators, Chaos Solitons Fractals 41 (2009) 451-456.
  78. O. Duman, M. A. Özarslan and B. Della Vecchia, Modified Szasz-Mirakjan-Kantorovich operators preserving linear functions, Turkish J. Math. 33 (2009) 151-158.
  79. C. Çelik and O. Duman, Allee effect in a discrete-time predator-prey system, Chaos Solitons Fractals 40 (2009) 1956-1962.
  80. H. Merdan and O. Duman, On the stability analysis of a general discrete-time population model involving predation and Allee effects, Chaos Solitons Fractals 40 (2009) 1169-1175.
  81. G. A. Anastassiou and O. Duman, High order statistical fuzzy Korovkin theory, Stoch. Anal. Appl. 27 (2009) 543-554.
  82. H. Merdan, O. Duman, Ö. Akın and C. Çelik, Allee effects on population dynamics in continuous (overlapping) case, Chaos Solitons Fractals 39 (2009) 1994-2001.
  83. G. A. Anastassiou, O. Duman and E. Erkuş-Duman, Statistical approximation for stochastic processes, Stoch. Anal. Appl. 27 (2009) 460-474.
  84. G. A. Anastassiou and O. Duman, Statistical weighted approximation to derivatives of functions by linear operator, J. Comput. Anal. Appl. 11 (2009) 20-30.
  85. Ö. Ocalan and O. Duman, Oscillation analysis of neutral difference equations with delays, Chaos Solitons Fractals 39 (2009) 261-270.
  86. G. A. Anastassiou and O. Duman, On relaxing the positivity condition of linear operators in statistical Korovkin-type approximations, J. Comput. Anal. Appl. 11 (2009) 7-19.
  87. G. A. Anastassiou and O. Duman, Fractional Korovkin theory based on statistical convergence, Serdica Math. J. 35 (2009) 381-396.
  88. M. A. Özarslan and O. Duman, A new approach in obtaining a better estimation in approximation by positive linear operators, Commun. Fac. Sci. Univ. Ank. Sér. A1 Math. Stat. 58 (2009) 17-22.
  89. G. A. Anastassiou and O. Duman, Statistical approximation to periodic functions by a general class of linear operators, J. Concr. Appl. Math. 7 (2009) 200-207.
  90. M. Burgin and O. Duman, Properties of fuzzy statistical limits, J. Intell. Fuzzy Systems 19 (2008) 385-392.
  91. M. A. Özarslan and O. Duman, Approximation properties of Poisson integrals for orthogonal expansions, Taiwanese J. Math. 12 (2008) 1147-1163.
  92. M. A. Özarslan, O. Duman and H. M. Srivastava, Statistical approximation results for Kantorovich-type operators involving some special functions, Math. Comput. Modelling 48 (2008) 388-401.
  93. O. Duman, A-Statistical convergence of sequences of convolution operators, Taiwanese J. Math. 12 (2008) 523-536.
  94. M. Burgin and O. Duman, Statistical fuzzy convergence, Internat. J. Uncertain. Fuzziness Knowledge-Based Systems 16 (2008) 879-902.
  95. O. Duman and C. Orhan, Rates of A-statistical convergence of operators in the space of locally integrable functions, Appl. Math. Lett. 21 (2008) 431-435.
  96. C. Çelik, H. Merdan, O. Duman and Ö. Akın, Allee effects on population dynamics with delay, Chaos Solitons Fractals 27 (2008) 65-74.
  97. E. Erkuş-Duman and O. Duman, Integral-type generalizations of operators obtained from certain multivariate polynomials, Calcolo 45 (2008) 53-67.
  98. M. A. Özarslan and O. Duman, Local approximation results for Szasz-Mirakjan type operators, Arch. Math. (Basel) 90 (2008) 144-149.
  99. O. Duman and G. A. Anastassiou, On statistical fuzzy trigonometric Korovkin theory, J. Comput. Anal. Appl. 10 (2008) 333-344.
  100. G. A. Anastassiou and O. Duman, A Baskakov type generalization of statistical Korovkin theory, J. Math. Anal. Appl. 340 (2008) 476-486.
  101. O. Duman, M. A. Özarslan and H. Aktuğlu, Better error estimation for Szasz-Mirakjan-Beta operators, J. Comput. Anal. Appl. 10 (2008) 53-59.
  102. S. Karakuş, K. Demirci and O. Duman, Equi-statistical convergence of positive linear operators, J. Math. Anal. Appl. 339 (2008) 1065-1072.
  103. G. A. Anastassiou and O. Duman, Statistical fuzzy approximation by fuzzy positive linear operators, Comput. Math. Appl. 55 (2008) 573-580.
  104. S. Karakus, K. Demirci and O. Duman, Statistical convergence on intuitionistic fuzzy normed spaces, Chaos Solitons Fractals 35 (2008) 763-769.
  105. O. Duman and M. A. Özarslan, Szasz-Mirakjan type operators providing a better error estimation, Appl. Math. Lett. 20 (2007) 1184-1188.
  106. B. Della Vecchia and O. Duman, Weighted approximation by Meyer-König and Zeller type operators, Studia Sci. Math. Hungar. 44 (2007) 445-467.
  107. M. A. Özarslan and O. Duman, MKZ type operators providing a better estimation on [1/2,1), Canadian Math. Bull. 50 (2007) 434-439.
  108. O. Duman, Regular matrix transformations and rates of convergence of positive linear operators, Calcolo 44 (2007) 159-165.
  109. O. Duman, Korovkin type approximation theorems via I-convergence, Czechoslovak Math. J. 57 (2007) 367-375.
  110. O. Duman, Higher order generalization of positive linear operators defined by a class of Borel measures, Turkish J. Math. 31 (2007) 333-339.
  111. O. Duman and E. Erkuş, Approximation of continuous periodic functions via statistical convergence, Comput. Math. Appl. 52 (2006) 967-974.
  112. E. Erkuş, O. Duman and H. M. Srivastava, Statistical approximation of certain positive linear operators constructed by means of the Chan-Chyan-Srivastava polynomials, Appl. Math. Comput. 182 (2006) 213-222.
  113. O. Duman, E. Erkuş and V. Gupta, Statistical rates on the multivariate approximation theory, Math. Comput. Modelling 44 (2006) 763-770.
  114. O. Duman, Statistical approximation theorems by k-positive linear operators, Arch. Math. (Basel) 86 (2006) 569-576.
  115. O. Duman, M. A. Özarslan and O. Doğru, On integral type generalizations of positive linear operators, Studia Math. 174 (2006) 1-12.
  116. O. Doğru and O. Duman, Statistical approximation of Meyer König and Zeller operators based on \(q\)-integers, Publ. Math. Debrecen 68 (2006) 199-214.
  117. E. Erkuş and O. Duman, A Korovkin type approximation theorem in statistical sense, Studia Sci. Math. Hungar. 43 (2006) 285-294.
  118. O. Duman and C. Orhan, An abstract version of the Korovkin approximation theorem, Publ. Math. Debrecen 69 (2006) 33-46.
  119. M. A. Özarslan, O. Duman and O. Doğru, A-Statistical convergence for a class of positive linear operators, Rev. Anal. Numér. Théor. Approx. 35 (2006) 161-172.
  120. E. Erkuş and O. Duman, A-statistical extension of the Korovkin type approximation theorem, Proc. Indian Acad. Sci. Math. Sci. 115 (2005) 499-508.
  121. M. A. Özarslan, O. Duman and O. Doğru, Rates of A-statistical convergence of approximating operators, Calcolo 42 (2005) 93-104.
  122. O. Duman and C. Orhan, Rates of A-statistical convergence of positive linear operators, Appl. Math. Lett. 18 (2005) 1339-1344.
  123. O. Duman, The effects of matrix summability methods on bounds of function sequences, Appl. Math. Lett. 17 (2004) 1221-1229.
  124. O. Duman and C. Orhan, Statistical approximation by positive linear operators, Studia Math. 161 (2004) 187-197.
  125. O. Duman and C. Orhan, Mu-Statistically convergent function sequences, Czechoslovak Math. J. 54 (2004) 413-422.
  126. O. Duman and C. Orhan, Statistical approximation in the space of locally integrable function, Publ. Math. Debrecen 63 (2003) 133-144.
  127. O. Duman, M. K. Khan and C. Orhan, A-statistical convergence of approximatig operators, Math. Inequal. Appl. 6 (2003) 689-699.
  128. O. Doğru, O. Duman and C. Orhan, Statistical approximation by generalized Meyer-König and Zeller type operators, Studia Sci. Math. Hungar. 40 (2003) 359-371.
  129. O. Duman, Statistical approximation for periodic functions, Demonstratio Math. 36 (2003) 873-878.

Invited Talks:

  1. "Operatörler ve Yaklaşım Teorisi", Bahar Matematik Buluşması, Bilkent Üniversitesi, Ankara, Türkiye, 10 Mayıs 2025.
  2. "Yaklaşım Teorisinde Son Gelişmeler: Modifiye Shepard Yaklaşımı", Hacettepe Üniversitesi, Ankara, Türkiye, 24 Nisan 2024.
  3. "Doğada Matematik", Evreni Anlama Sanatı: Temel Bilimler Konferansı, Selçuk Üniversitesi, Konya, Türkiye, 12 Ekim, 2022.
  4. "Kompleks Shepard Operatörleri ve Uygulamaları", Yaklaşımlar Teorisi ve Uygulamaları Çalıştayı, Hacettepe Üniversitesi, Ankara, Türkiye, 4 Mart 2022.
  5. "Lineer Olmayan Operatörlerle Fonksiyonlara Yaklaşım ve Toplanabilme", Mersin Üniversitesi, Matematik Bölümü, Mersin, Türkiye, 26 Ekim 2018.
  6. "Summability Methods in Singular Approximation", Çankaya University, Department of Mathematics, Ankara, Türkiye, November 09, 2016.
  7. "Iraksak Seriler, Toplanabilme ve Hardy", Doğu Akdeniz Üniversitesi, Matematik Bölümü, Gazimagosa, KKTC, Mart 20, 2015.
  8. "Toplanabilme Teorisinin Yaklaşımlar Teorisi Üzerindeki Etkileri", Anadolu Üniversitesi, Eskişehir, Türkiye, Mayıs 23, 2013.
  9. "Yaklaşımlar Teorisinde Yeni Yaklaşım Tekniklerinin İhtiyacı", TÜBA Konferansları, Karabük Üniversitesi, Karabük, Türkiye, Nisan 26, 2013.
  10. "Convergence Methods in Approximation Theory", Bilkent University, Ankara, Türkiye, November 16, 2011.
  11. "Recent Developments in Approximation Theory", TOBB University of Economics and Technology, Ankara, Türkiye, October 12, 2011.
  12. "Recent Improvements on Statistical Approximation Theory", İzmir University of Economics, İzmir, Türkiye, April 26, 2010.
  13. "Uniform Statistical Approximation by Double Gauss-Weierstrass Singular Integral Operators", Gazi University, Ankara, Türkiye, November 06, 2009.
  14. "A Baskakov Type Generalization of Statistical Korovkin Theory", Ankara University, Ankara, Türkiye, April 15, 2009.
  15. "Statistical Convergence and Korovkin-Type Approximation Theory", International Conference on Mathematical Analysis, Differential Equations and Their Applications, Eastern Mediterranean University, Famagusta-North Cyprus, September 12-15, 2008.
  16. "On Relaxing the Positivity Condition of Linear Operators in Statistical Korovkin-Type Approximations", Ankara University, Ankara, Türkiye, April 30, 2008.
  17. "Allee Effects on Population Dynamics", Çankaya University, Nano-Science and Research Center, Ankara, Türkiye, December 27, 2007.
  18. "Approximation Properties of Positive Linear Operators", Çankaya University, Ankara, Türkiye, December 15, 2006.
  19. "Statistical Approximation by Positive Linear Operators", Middle East Technical University, Ankara, Türkiye, March 24, 2005.
  20. "A-Statistical Convergence of Approximating Operators", Ankara University, Ankara, Türkiye, May 20, 2004.

International / National Contributed Talks:

  1. O. Duman, İnterpolasyon ve yaklaşımlar, "16. Ankara Matematik Günleri - AMG 2025", Çankaya Üniversity, Ankara, Türkiye, June 19-20, 2025.
  2. M. E. Alemdar and O. Duman, Voronovskaja type results for modified Bernstein operators, "Approximation Theory and Special Functions - ATSF 2024 Conference - 8th Series", Ankara, Türkiye, September 4-7, 2024.
  3. M. E. Alemdar and O. Duman, Regular summability methods in the approximation by Bernstein-Chlodovsky type operators, "The 7th International Conference on Recent Advances in Pure and Applied Mathematics - ICRAPAM 2020", Muğla, Türkiye, September 25-28, 2020.
  4. T. Y. Gökçer and O. Duman, Approximation theorems for max-min operators via summability methods, "The 7th International Conference on Recent Advances in Pure and Applied Mathematics - ICRAPAM 2020", Muğla, Türkiye, September 25-28, 2020.
  5. T. Y. Gokcer and O. Duman, General approach for approximation by max-min operators, "The 8th International Conference on Pure and Applied Mathematics - ICPAM 2019", Brussels, Belgium, July 22-25, 2019.
  6. M. E. Alemdar and O. Duman, On the approximation by Bernstein-Chlodovsky type operators, "The 8th International Conference on Pure and Applied Mathematics - ICPAM 2019", Brussels, Belgium, July 22-25, 2019.
  7. I. Aslan and O. Duman, Summability method in the approximation by nonlinear integral operators in \(N\)-dimension BV-space, "The 7th International Conference on Pure and Applied Mathematics - ICPAM 2018", Eötvös Lorand University, Budapest, Hungary, July 10-13, 2018.
  8. T. Y. Gokcer and O. Duman, Some convergence methods on max-min operators, "The 7th International Conference on Pure and Applied Mathematics - ICPAM 2018", Eötvös Lorand University, Budapest, Hungary, July 10-13, 2018.
  9. I. Aslan and O. Duman, Approximation by nonlinear integral operators with the help of summation methods, "The International Society for Analysis, its Applications and Computation - ISAAC 2017", Linnaeus University, Vaxjo, Sweden, August 14-18, 2017.
  10. T. Y. Gokcer and O. Duman, Some convergence methods on pseudo linear operators, "The International Society for Analysis, its Applications and Computation - ISAAC 2017", Linnaeus University, Vaxjo, Sweden, August 14-18, 2017.
  11. C. Turkun and O. Duman, Neural network approximation in summation process, "The International Society for Analysis, its Applications and Computation - ISAAC 2017", Linnaeus University, Vaxjo, Sweden, August 14-18, 2017.
  12. T. Y. Gokcer and O. Duman, On the approximation by max-min and max-product operators, "International Conference on Mathematics and Mathematics Education - ICMME 2017", Harran University, Şanlıurfa, Türkiye, May 11-13, 2017.
  13. İ. Aslan and O. Duman, Summability process on the approximation by nonlinear integral operators of convolution type, "International Conference on Mathematics and Mathematics Education - ICMME 2017", Harran University, Şanlıurfa, Türkiye, May 11-13, 2017.
  14. T. Y. Gokcer and O. Duman, Summation Process in Approximation by Nonlinear Operators, "Emerging Trends in Applied Mathematics and Mechanics – ETAMM 2016", Perpignan, France, May 30 - June 03, 2016.
  15. C. Turan and O. Duman, Hardy Type Tauberian Condition on Time Scales, "Emerging Trends in Applied Mathematics and Mechanics – ETAMM 2016", Perpignan, France, May 30 - June 03, 2016.
  16. İ. Aslan and O. Duman, A Generalized Version of the Korovkin Theory, "Emerging Trends in Applied Mathematics and Mechanics – ETAMM 2016", Perpignan, France, May 30 - June 03, 2016.
  17. T. Y. Gokcer and O. Duman, Summation process by max-product operators, "3rd International Conference on Applied Mathematics and Approximation Theory - AMAT 2015", Ankara, Türkiye, May 28-31, 2015.
  18. C. Turan and O. Duman, On convergence methods of functions defined on time scales, "International Conference on Recenet Developments in Pure and Applied Mathematics - ICRAPAM 2014", Antalya, Türkiye, November 06-09, 2014.
  19. İ. Aslan and O. Duman, Application of summability process on Baskakov-type approximation theory, "International Conference on Recenet Developments in Pure and Applied Mathematics - ICRAPAM 2014", Antalya, Türkiye, November 06-09, 2014.
  20. C. Turan and O. Duman, Recent developments on convergence methods on time scales, “International Conference: Mathematics Days in Sofia - MDS 2014", Sofia, Bulgaria, July 07-10, 2014.
  21. İ. Aslan and O. Duman, Summability process on the Baskakov-type approximation theory, “International Conference: Mathematics Days in Sofia - MDS 2014", Sofia, Bulgaria, July 07-10, 2014.
  22. N. Küçük and O. Duman, Summability methods in the weighted approximation to derivatives of functions, “International Conference: Mathematics Days in Sofia - MDS 2014", Sofia, Bulgaria, July 07-10, 2014.
  23. C. Turan and O. Duman, Convergence methods on time scales, "11th International Conference of Numerical Analysis and Applied Mathematics - ICNAAM 2013", Rhodes Island, Greece, September 21-27, 2013.
  24. O. Duman, Summability process by Mastroianni operators, "26th. National Mathematics Symposium, Diyarbakır, Türkiye, September 4-7, 2013.
  25. C. Turan and O. Duman, Statistical convergence on time scales, "International Conference on Applied Mathematics and Approximation Theory - AMAT 2012", Ankara, Türkiye, May 17-20, 2012.
  26. O. Duman and E. Erkuş-Duman, Approximation by matrix-valued linear positive operators, "Conference on Matrix Analysis and its Applications - MAT TRIAD 2011", Tomar, Portugal, July 12-16, 2011.
  27. O. Duman, Statistical approximation by double Picard singular integral operators, "4th Ankara Mathematics Days", METU, Ankara, Türkiye, June 04-05, 2009.
  28. O. Duman, Stability analysis of population dynamics under Allee effects (poster presentation), "International Workshop on New Trends in Science and Technology", Çankaya University, Ankara, Türkiye, November 03-04, 2008.
  29. O. Duman, Statistical convergence and Korovkin-type approximation theory, "Mathematical Analysis, Differential Equations and Their Applications", Eastern Mediterranean University, Famagusta, North Cyprus, September 12-15, 2008.
  30. O. Duman, A new approach in obtaining a better estimation in the approximation by positive linear operators, "3rd Ankara Mathematics Daysi", Ankara University, Ankara, Türkiye, May 22-23, 2008.
  31. O. Duman and E. Erkuş-Duman, Statistical approximation to continuous periodic functions by means of positive linear operators, "2nd Turkish World Mathematics Symposium", Sakarya University, Sakarya, Türkiye, July 04-07, 2007.
  32. O. Duman, Stability analysis of delay population dynamics under Allee effects, "TASSA Conference", Yale University, New Haven-USA, March 24-25, 2007.
  33. O. Duman and M.A. Özarslan, MKZ type positive linear operators providing a better error estimation, "19th National Mathematics Symposium", Kütahya, Türkiye, August 22-25, 2006.
  34. O. Duman and C. Orhan, Rates of A-statistical convergence of positive linear operators, "Fejer-Riesz Conference", Eger, Hungary, June 09-13, 2005.