Branch values in Ahlfors’ theory of covering surfaces  

作　　者：Zonghan Sun Guangyuan Zhang 

机构地区：[1]Department of Mathematical Sciences,Tsinghua University,Beijing 100084,China

出　　处：《Science China Mathematics》2020年第8期1535-1558,共24页中国科学：数学（英文版）

基　　金：supported by National Natural Science Foundation of China(Grant No.11531007)。

摘　　要：In the study of the constant in Ahlfors’second fundamental theorem involving a set Eq consisting of q points,branch values of covering surfaces outside Eq bring a lot of troubles.To avoid this situation,for a given surfaceΣ0,it is useful to construct a new surfaceΣ1,such that L(■Σ1)≤L(■Σ0),and H(Σ1,Eq)≥H(Σ0,Eq).and all branch values ofΣ1 are contained in Eq.The goal of this paper is to prove the existence of suchΣ1,which generalizes a result found by Zhang(2013).

关 键 词：covering surfaces Ahlfors’theory Ahlfors’constant branch values 

分 类 号：O186.11[理学—数学]