学术报告
The two ways of stability in dimension 2: normal hyperbolicity and tangential twist-Alain CHENCINER （巴黎七大，巴黎天文台）
题目：The two ways of stability in dimension 2: normal hyperbolicity and tangential twist
报告人：Alain CHENCINER （巴黎七大，巴黎天文台）
摘要：Perturbing the germ at the origin of a rotation $re^{i/theta}/mapsto re^{i(/theta+/omega)}$ of the plane leads to two celebrated results: the Andronov-Hopf bifurcation of invariant curves under a generic radial hypothesis of weak attraction (or repulsion) and the Moser invariant curve theorem under a tangential twist hypothesis in the area preserving case.
The invariant curves whose existence is proved are normally hyperbolic with generic induced dynamics in the first case, with a dynamics smoothly conjugated to a diophantine rotation in the second one. In generic 2-parameter families of germs of diffeomorphisms of the plane near a fixed point, the tension between radial and tangential (or hyperbolic and elliptic) behaviour leads to phenomena where the whole richness of the area preserving situation is unfolded along some direction of the parameter space.
时间：3月9日 （星期四）上午 9:00-10:00
地点：首都师范大学新教二楼608
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