On the five-point theorems due to Lappan
Volume 101 / 2011
Annales Polonici Mathematici 101 (2011), 227-235
MSC: Primary 30D05; Secondary 30D45.
DOI: 10.4064/ap101-3-3
Abstract
By using an extension of the spherical derivative introduced by Lappan, we obtain some results on normal functions and normal families, which extend Lappan's five-point theorems and Marty's criterion, and improve some previous results due to Li and Xie, and the author. Also, another proof of Lappan's theorem is given.
