Browsing by Author "Kumar, Sushil"

Now showing 1 - 3 of 3
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    Applications of first order differential subordination for functions with positive real part
    (Babes-Bolyai University, 2018-09-26) Ahuja, Om P.; Kumar, Sushil; Ravichandran, V
    Several inclusions between the class of functions with positive real part and the class of starlike univalent functions associated with lemniscate of Bernoulli are obtained by making use of the well-known theory of differential subordination. Further, these inclusions give sufficient conditions for normalized analytic functions to belong to some subclasses of starlike functions. The results also provide sharp version of some previously known results.
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    Differential subordination for Janowski functions with positive real part
    (Babes-Bolyai University, 2021-09-28) Anand, Swati; Kumar, Sushil; Ravichandran, V
    Theory of differential subordination provides techniques to reduce differential subordination problems into verifying some simple algebraic condition called admissibility condition. We exploit the first order differential subordination theory to get several sufficient conditions for function satisfying several differential subordinations to be a Janowski function with positive real part. As applications, we obtain sufficient conditions for normalized analytic functions to be Janowski starlike functions.
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    Starlike functions related to the bell numbers
    (MDPI AG, 2019-02-13) Cho, Nak Eun; Kumar, Sushil; Kumar, Virendra; Ravichandran, V; Srivastava, H. M.
    The present paper aims to establish the first order differential subordination relations between functions with a positive real part and starlike functions related to the Bell numbers. In addition, several sharp radii estimates for functions in the class of starlike functions associated with the Bell numbers are determined. © 2019 by the authors.