Some Applications of Nunokawa’s Lemma
The purpose of the present paper is to prove a geometric property for analytic functions p in the open unit disk with \(p(0)=1\) by using Nunokawa’s result, which is a generalized form of well-known Jack’s lemma. This property concerns a boundary behavior of the functions p. As the applications of the main result, we obtain a few corollaries where several sufficient conditions for p to be of the real part greater than a given number \(\beta \ (0\le \beta <1)\) are also investigated.
KeywordsAnalytic functions Convex functions Starlike functions Univalent functions
Mathematics Subject Classification30C45 30C80
The authors would like to express their thanks to the editor, Professor Rosihan M. Ali and the reviewers for many valuable advices regarding a previous version of this paper. This research was supported by the Basic Science Research Program through the National Research Foundation of Korea (NRF) and funded by the Ministry of Education, Science and Technology (No. 2011-0007037).