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YALÇIN TOKGÖZ, SİBEL

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YALÇIN TOKGÖZ

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SİBEL

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Now showing 1 - 10 of 60
  • Publication
    On a new class of salagean-type harmonic univalent functions associated with subordination
    (Honam Mathematical Soc, 2018-09-01) Altınkaya, Şahsene; Çakmak, Serkan; Yalçın, Sibel; ALTINKAYA, ŞAHSENE; Çakmak, Serkan; YALÇIN TOKGÖZ, SİBEL; Uludağ Üniversitesi/Fen-Edebiyat Fakültesi/Matematik Bölümü; 0000-0002-7950-8450; 0000-0002-0243-8263; AAA-8330-2021; AAE-9745-2020; GZG-2072-2022
    In this present investigation, we introduce a new class of harmonic univalent functions of the form f = h + (g) over bar in the open unit disk Delta. We get basic properties, like, necessary and sufficient convolution conditions, distortion bounds, compactness and extreme points for these classes of functions.
  • Publication
    Coefficient estimates for a certain subclass of bi- univalent functions
    (Univ Studi Catania, Dipt Matematica, 2016-01-01) Altınkaya, Şahsene; ALTINKAYA, ŞAHSENE; Yalçın, Sibel; YALÇIN TOKGÖZ, SİBEL; Bursa Uludağ Üniversitesi/Fen Edebiyat Fakültesi/Matematik Bölümü.; 0000-0002-7950-8450; 0000-0002-0243-8263; AAA-8330-2021; ABC-6175-2020; AAE-9745-2020
    In the present investigation, we find estimates on the coefficients broken vertical bar a(2) broken vertical bar and broken vertical bar a(3) broken vertical bar for functions in the function class S-Sigma ( lambda,h). The results presented in this paper improve or generalize the recent work of Magesh and Yamini.
  • Publication
    Third hankel determinant and zalcman functional for a class of starlike functions with respect to symmetric points related with sine function
    (Int Scientific Research Publications, 2022-01-01) Khan, Muhammad Ghaffar; Ahmad, Bakhtiar; Murugusundaramoorthy, Gangadharan; Mashwani, Wali Khan; Yalçın, Sibel; Shaba, Timilehin Gideon; Salleh, Zabidin; YALÇIN TOKGÖZ, SİBEL; Bursa Uludağ Üniversitesi/Fen-Edebiyat Fakültesi/Matematik Bölümü; 0000-0002-0243-8263; AAE-9745-2020
    In this article we define a class of starlike functions with respect to symmetric points in the domain of sine function. Also, we investigate coefficients bounds and upper bounds for the third order Hankel determinant for this defined class. We also evaluate the Zalcman functiona vertical bar a2/3 - a(5)vertical bar. Specializing the parameters, we improve Zalcman functional for the class of starlike functions.
  • Publication
    Coefficient bounds for certain subclasses of m-fold symmetric biunivalent functions
    (Hindawi, 2015-01-01) Altınkaya, Şahsene; Yalçın, Sibel; ALTINKAYA, ŞAHSENE; YALÇIN TOKGÖZ, SİBEL; Uludağ Üniversitesi/Fen-Edebiyat Fakültesi/Matematik Bölümü; 0000-0002-7950-8450; 0000-0002-0243-8263; AAE-9745-2020; AAA-8330-2021
    We consider two new subclasses S-Sigma m(alpha,lambda) and S-Sigma m (beta,lambda) of Sigma(m) consisting of analytic and m-fold symmetric biunivalent functions in the open unit dis U. Furthermore, we establish bounds for the coefficients for these subclasses and several related classes are also considered and connections to earlier known results are made.
  • Publication
    Some basic geometric properties of a subclass of harmonic mappings
    (Springer Int Publ Ag, 2022-07-01) YAŞAR, ELİF; Çakmak, Serkan; Yaşar, Elif; YALÇIN TOKGÖZ, SİBEL; Yalçın, Sibel; Bursa Uludağ Üniversitesi/Fen Edebiyat Fakültesi/Matematik Anabilim Dalı.; 0000-0003-0176-4961; 0000-0002-0243-8263; AAE-9745-2020; GZG-2072-2022; AAG-8247-2021
    In the present paper, a new subclass of complex-valued harmonic functions in the open unit disk is introduced and coefficient bounds, growth estimates, radius of univalency, radius of starlikeness and radius of convexity of this class are investigated. In addition, it is shown that this class is closed under convolution of its members.
  • Publication
    Second hankel determinant for a general subclass of bi-univalent functions
    (Inst Applied Mathematics, 2016-01-01) Altınkaya, Şahsene; Yalçın, Sibel; ALTINKAYA, ŞAHSENE; YALÇIN TOKGÖZ, SİBEL; Uludağ Üniversitesi/Fen-Edebiyat Fakültesi/Matematik Bölümü; 0000-0002-7950-8450; 0000-0002-0243-8263; ABC-6175-2020; AAE-9745-2020; AAA-8330-2021
    Making use of the Hankel determinant, in this work, we consider a general subclass of bi-univalent functions. Moreover, we investigate the bounds of initial coefficients of this class.
  • Publication
    The fekete-szego problem for a general class of bi-univalent functions satisfying subordinate conditions
    (Univ Maragheh, 2017-12-01) Altınkaya, Şahsene; Yalçın, Sibel; ALTINKAYA, ŞAHSENE; YALÇIN TOKGÖZ, SİBEL; Uludağ Üniversitesi/Fen-Edebiyat Fakültesi/Matematik Bölümü; 0000-0002-0243-8263; AAE-9745-2020; AAA-8330-2021
    In this work, we obtain the Fekete-Szego inequalities for the class P-Sigma (lambda, phi) of bi-univalent functions. The results presented in this paper improve the recent work of Prema and Keerthi [11].
  • Publication
    Coefficient estimates for certain subclasses of analytic functions defined by new operator
    (Amer Inst Physics, 2021-01-01) Cakalli, H; Kocinac, LDR; Ashyralyev, A; Harte, R; Dik, M; Canak, I; Kandemir, HS; Tez, M; Gurtug, O; Savas, E; Akay, KU; Ucgun, FC; Uyaver, S; Ashyralyyev, C; Sezer, SA; Turkoglu, AD; Onvural, OR; Sahin, H; Bayram, Hasan; BAYRAM, HASAN; Yalcin, Sibel; YALÇIN TOKGÖZ, SİBEL; Bursa Uludağ Üniversitesi/Fen Edebiyat Fakültesi/Matematik Bölümü.; Bursa Uludağ Üniversitesi/Fen Edebiyat Fakültesi/Matematik Bölümü.; Cakalli, H; Kocinac, LDR; Ashyralyev, A; Harte, R; Dik, M; Canak, I; Kandemir, HS; Tez, M; Gurtug, O; Savas, E; Akay, KU; Ucgun, FC; Uyaver, S; Ashyralyyev, C; Sezer, SA; Turkoglu, AD; Onvural, OR; Sahin, H; 0000-0001-8106-6834; 0000-0002-0243-8263; B-1379-2014; AAE-9745-2020
    In this paper, we investigate certain subclasses of analytic functions defined by generalized differential operators involving binomial series. Also, we obtain coefficient estimates involving of the nonhomogeneous Cauchy-Euler differential equation of order r.
  • Publication
    Some properties associated to a certain class of starlike functions
    (Walter, 2019-12-01) Masih, Vali Soltani; Ebadian, Ali; Yalçın, Sibel; YALÇIN TOKGÖZ, SİBEL; Bursa Uludağ Üniversitesi/Fen-Edebiyat Fakültesi/Matematik Bölümü; 0000-0002-0243-8263; AAE-9745-2020; ABC-6175-2020
    Let A denote the family of analytic functions f with f(0) = f'(0) - 1 = 0, in the open unit disk Delta. We consider a classS-cs(*)(alpha) := {f is an element of A : (zf'(z)/f(z) -1) (sic) z/1+(alpha-1)z-alpha z(2) , z is an element of Delta},where 0 <= alpha <= 1/2, and (sic) is the subordination relation. The methods and techniques of geometric function theory are used to get characteristics of the functions in this class. Further, the sharp inequality for the logarithmic coefficients gamma(n) of f is an element of S-cs(*)(alpha):Sigma(infinity)(n=1) vertical bar gamma n vertical bar(2) <= 1/4(1+alpha)(2) (pi(2)/6 - 2Li(2) (-alpha)+Li-2 (alpha(2))),where Li-2 denotes the dilogarithm function are investigated.
  • Publication
    Coefficient bounds for a general subclass of bi-univalent functions
    (Univ Studi Catania, 2016-01-01) Altınkaya, Şahsene; Yalçın, Sibel; ALTINKAYA, ŞAHSENE; YALÇIN TOKGÖZ, SİBEL; Uludağ Üniversitesi/Fen-Edebiyat Fakültesi/Matematik Bölümü; 0000-0002-0243-8263; AAE-9745-2020; AAA-8330-2021
    In the present investigation, we introduce and investigate a new subclass of the function class Sigma of bi-univalent functions defined in the open unit disc. We find estimates on the coefficients vertical bar a(2)vertical bar and vertical bar a(3)vertical bar for functions in the function class S-Sigma (n, h, lambda). The results presented in this paper improve or generalize the recent works of Jothibasu [13] and other authors.