时间：12月4日（周五）下午2:00-3:00

地点：腾讯会议  450 591 424

报告人：柳彬（北京大学教授，杰青）

题目: Unbouded solutions for a sublinear Duffng Equation

摘要:  We are concerned with the existence of unbounded solutions for the following equations $x^{\prime\prime}+a(t)g(x) = 0$, where g is sublinear, and the periodic function $a$ has negative average value.

时间：12月4日（周五）下午3:00-4:00

地点：腾讯会议  450 591 424

报告人：柳彬（北京大学教授，杰青）

题目: Completely degenerate lower-dimensional invarianti tori for Hamiltonian

摘要: We talk about the persistence of lower-dimensional invariant tori for a nearly integrable completely degenerate Hamiltonian system. It is shown that the majority of unperturbed invariant tori can survive from the perturbations which are only assumed the smallness and smoothness.

时间：12月4日（周五）下午4:00-5:00

地点：腾讯会议  450 591 424

报告人：柳彬（北京大学教授，杰青）

题目: Almost periodic solutions for an asymmetric oscillation

摘要:  We study the dynamical behavior of the differential equation x^{\prime\prime} +ax^+ − bx^− = f (t), where x^+=max{x, 0}, x^−=max{−x, 0}, a and b are two different positive constants, f(t) is a real analytic almost periodic function. For this purpose, firstly, we have to establish some variants of the invariant curve theorem of planar almost periodic mappings, and then we will discuss the existence of almost periodic solutions and the boundedness of all solutions for the above asymmetric oscillation.