Characterization and the pre-Schwarzian norm estimate for concave univalent functions

B. Bhowmik, S. Ponnusamy, K-J. Wirths

Let $Co(\alpha )$ denote the class of concave univalent functions in the unit disk $\ID$. Each function $f\in Co(\alpha )$ maps the unit disk $\ID$ onto the complement of an unbounded convex s…