Published online by Cambridge University Press: 20 November 2018
Let f(z) be a function meromorphic in the unit disc D = (|z| < 1). We consider the maximum modulus
and the minimum modulus
When no confusion is likely, we shall write M(r) and m(r) in place of M(r,f) and m(r,f).
Since every normal holomorphic function belongs to an invariant normal family, a theorem of Hayman [6, Theorem 6.8] yields the following result.
THEOREM 1. If f(z) is a normal holomorphic function in the unit disc D, then
(1)
This means that for normal holomorphic functions, M(r) cannot grow too rapidly. The main result of this paper (Theorem 5, also due to Hayman, but unpublished) is that a similar situation holds for normal meromorphic functions.