Title of article :
A non explicit counterexample to a problem of quasi-normality
Author/Authors :
Grahl، نويسنده , , Jürgen and Nevo، نويسنده , , Shahar and Pang، نويسنده , , Xuecheng، نويسنده ,
Issue Information :
دوهفته نامه با شماره پیاپی سال 2013
Abstract :
In 1986, S.Y. Li and H. Xie proved the following theorem: let k ≥ 2 and let F be a family of functions meromorphic in some domain D , all of whose zeros are of multiplicity at least k . Then F is normal if and only if the family F k = { f ( k ) 1 + | f | k + 1 : f ∈ F } is locally uniformly bounded in D .
e give, in the case k = 2 , a counterexample to show that if the condition on the multiplicities of the zeros is omitted, then the local uniform boundedness of F 2 does not even imply quasi-normality. In addition, we give a simpler proof for the Li–Xie theorem (and an extension of it) that does not use Nevanlinna’s Theory which was used in the original proof.
Keywords :
Quasi-normal family , Zalcman’s lemma , Differential inequality , interpolation theory
Journal title :
Journal of Mathematical Analysis and Applications
Journal title :
Journal of Mathematical Analysis and Applications