题目：Some problems in the unique normal formtheory
陈国廷 （法国里尔第一大学数学系主任）
时间：7月24日 维格堂113 8：30-9：20
摘要：我们将先介绍唯一正规型理论的一般方法. 然后讨论几个具体的正规型问题:
平面幂零向量场, Hopf-zero向量场，带参数距阵的正规型.
题目：Center of planar quasi-homogeneouspolynomial differential systems
于江（教授，上海交通大学）
时间：7月24日 维格堂113 9：30-10：20
摘要：In this paper, we characterize thecenters of the quasi-homogeneous but non-homogeneous planar polynomialdifferential systems of any degree $n/in /mathbb N$. We prove that systems do not admit centers if $n$ is even,and present the sufficient and necessary conditions that the systems admit acenter if $n$ is odd. Furthermore, we provide an algorithm to obtainquasi-homogeneous but non-homogeneous systems with center for a given order. Asan example, we characterize the center of the quasi-homogeneous butnon-homogeneous of degree $7$.
题目： Versal unfolding of planar systems atdegenerate equilibria（I）（II）
唐异垒（副教授，上海交通大学）
时间：7月24日 维格堂113 1）； 10：30-11：20； 11：30-12：20
摘要： In this talk we study bifurcations of a planarsystem at a degenerate equilibrium,which has a zero linearization. We prove that such a degenerate system is ofcodimension 3 degeneracy in their classes. So we introduce unfolding parameters to versally unfold the degeneratesystems in the classes. We display allbifurcations such as pitchfork bifurcation, saddle-center bifurcation and theBogdanov-Takens bifurcati