Value distribution theory and the research of Yang Lo
This paper describes the important contributions due to Yang Lo in the field of value distribution theory of meromorphic functions over four decades. After a short introduction to the basic notions and key results of Nevanlinna theory, the main achievements due to Yang Lo are described in three sections: (1) Concerning angular distributions of meromorphic functions, his co-operation with Zhang Guanghou resulted in a number of remarkable results, including the Yang--Zhang theorem, that describes a close relation between the number of deficient values and the number of Borel directions. (2) As to the deficient values of meromorphic functions, the Yang Lo relation gives an extension involving multiplicities to the usual deficiency relation. (3) Finally, Yang Lo's results related to the Bloch principle for normal families are shortly presented. A complete list of publications by Yang Lo finishes the paper.
scientific article; zbMATH DE number 5712107
scientific article