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单位圆上解析函数的掩盖定理
Covering Theorems on the Analytic Functions in the Unit Disk
【摘要】 <正> 设w=f(z)是单位圆D上满足规范条件 f(0)=0,f′(0)=1的解析函数。众所周知,当f(z)是单叶解析函数时,有著名的Koebe的1/4掩盖定理。在去掉单叶性的假设时,对于函数
【Abstract】 In this paper, Koebe’s 1/4 covering theorem of univalent functions is extended to a similar result for analytic functions. Suppose that f(z) is analytic function in the unit disk D(|z|<1) with f(0)=0 and f’(0)=1, following covering properties are obtained. If E is an unbounded branch of C-f(D), then the distance between 0 and E e(0, E)≥1/4; if ?is a nondegenerate bounded branch of C-f(D), then p(0,E)≥MB, where MB is a constant which depends on E. Also if f(z) satisfies some additional condition which depends on the index n of f(z) and ?is a bounded branch of C-f(D), then it is proved that p(0, E)≥1/4n. Some spacial functions which indicated above results are sharp are constructed.
- 【文献出处】 数学进展 ,Advances In Mathematics , 编辑部邮箱 ,1991年01期
- 【被引频次】1
- 【下载频次】43