© 1998 by London Mathematical Society
© The London Mathematical Society
Functionals of Higher Derivative Type
Department of Mathematics, National University of Singapore 10 Kent Ridge Crescent, Singapore 119260. E-mail: matgohss{at}leonis.nus.edu.sg
Received 20 February 1996.
Functionals of higher derivative type are linear combinations of functionals of the form f
f(n)(
), where n
2 and 0<|
|<1. The paper shows that, if L is a functional of higher derivative type and f is a function in the class S of univalent functions that maximises Re{L} over S, then L(f)
0. In addition, if the function f is a rational function, then it must be a rotation of the Koebe function k(z)=z(1z)2. These results are applied to establish several cases of the two-functional conjecture for functionals of higher derivative type.