DOI QR코드

DOI QR Code

SUFFICIENT CONDITIONS FOR UNIVALENCE AND STUDY OF A CLASS OF MEROMORPHIC UNIVALENT FUNCTIONS

  • Received : 2017.05.24
  • Accepted : 2017.08.08
  • Published : 2018.05.31

Abstract

In this article we consider the class ${\mathcal{A}}(p)$ which consists of functions that are meromorphic in the unit disc $\mathbb{D}$ having a simple pole at $z=p{\in}(0,1)$ with the normalization $f(0)=0=f^{\prime}(0)-1$. First we prove some sufficient conditions for univalence of such functions in $\mathbb{D}$. One of these conditions enable us to consider the class ${\mathcal{A}}_p({\lambda})$ that consists of functions satisfying certain differential inequality which forces univalence of such functions. Next we establish that ${\mathcal{U}}_p({\lambda}){\subsetneq}{\mathcal{A}}_p({\lambda})$, where ${\mathcal{U}}_p({\lambda})$ was introduced and studied in [2]. Finally, we discuss some coefficient problems for ${\mathcal{A}}_p({\lambda})$ and end the article with a coefficient conjecture.

Keywords

References

  1. L. A. Aksentev, Sufficient conditions for univalence of regular functions, Izv. Vyss. Ucebn. Zaved. Matematika 4 (1958), no. 3, 3-7.
  2. B. Bhowmik and F. Parveen, On a subclass of meromorphic univalent functions, Complex Var. Elliptic Equ. 62 (2017), no. 4, 494-510. https://doi.org/10.1080/17476933.2016.1225203
  3. B. Bhowmik and F. Parveen, Criteria for univalence, integral means and dirichlet integral for meromorphic functions, Bull. Belg. Math. Soc. Simon Stevin 24 (2017), 427-438.
  4. B. Bhowmik, S. Ponnusamy, and K.-J. Wirths, Concave functions, Blaschke products and polygonal mappings, Sib. Math. J. 50 (2009), no. 4, 609-615. https://doi.org/10.1007/s11202-009-0068-6
  5. S. S. Miller and P. T. Mocanu, Differential Subordinations, Theory and Applications, Marcel Dekker Inc., New York, 1999.
  6. M. Obradovic and S. Ponnusamy, Univalence and starlikeness of certain integral transforms defined by convolution of analytic functions, J. Math. Anal. Appl. 336 (2007), no. 2, 758-767. https://doi.org/10.1016/j.jmaa.2007.03.020
  7. M. Obradovic and S. Ponnusamy, Criteria for univalent functions in the unit disk, Arch. Math. 100 (2013), no. 2, 149-157. https://doi.org/10.1007/s00013-012-0476-x
  8. M. Obradovic, S. Ponnusamy, and K.-J. Wirths, Geometric studies on the class U($\lambda$), Bull. Malays. Math. Sci. Soc. 39 (2016), no. 3, 1259-1284. https://doi.org/10.1007/s40840-015-0263-5
  9. S. Ponnusamy and K.-J. Wirths, Elementary consideration for classes of meromorphic univalent functions, Lobachevskii J. Math. (2018), To appear.