报告题目：Difference Nevanlinna theory and its applications

主讲人：Prof. Risto Korhonen

主持人：李叶舟

报告时间：2017年8月16日（周三）上午9：30—10：30

报告地点：主楼1214

报告摘要：

Certain estimates involving the derivative f' of a meromorphic function f play key roles in the construction and applications of classical Nevanlinna theory. In this talk we extend the usual Nevanlinna theory to a theory for the exact difference f(z+c)-f(z). One of the main results is an analogue of the second main theorem of Nevanlinna theory, where the usual ramification term is replaced by a quantity expressed in terms of the number of paired points of f. Corollaries of the theorem include analogues of the Nevanlinna defect relation, Picard's theorem and Nevanlinna's five value theorem. Applications to difference equations are discussed, and examples illustrating the use and sharpness of the results are given.

报告人简介：

Prof. Risto Korhonen ， Dean of Mathematics department, University of Eastern Finland.

PhD degree in mathematics in 2002 at the University of Joensuu. Research Associate at the mathematics department of Loughborough University from 2002 to 2004. Academy of Finland post-doc from 2004 to 2006, and Academy Research Fellow from 2006 to 2010. Since then, a professor of mathematics at the University of Eastern Finland. Current research interest are in value distribution theory and its analogues, and their applications to differential and difference equations.