学术报告
Birkhoff normal forms via mould calculus
题目：Birkhoff normal forms via mould calculus
报告人：Prof. David SAUZIN（France）
摘要：
Several normal form problems in dynamical systems (classical or quantum dynamics), among which Birkhoff normalization near an elliptic fixed point for a Hamiltonian system, can be rephrased as follows:
Given a Lie algebra, an element $X_0$ and a family $(B_n)$ of eigenvectors of $ad(X_0)$, we look for an element $Y$ such that the Lie algebra automorphism $exp(ad(Y))$ maps $X_0+/sum B_n$ to a "normal form", i.e. an element which commutes with $X_0$.
Ecalle's "mould calculus" gives rise to a surprisingly explicit formula, expressing $Y$ and the normal formal as Lie series, involving the iterated Lie brackets $[B_{n_1} , { B_{n_2}, ...]]$ and universal coefficients. The aim of this seminar is to explain this formalism and the kind of formula one can obtain.
Joint work with Thierry PAU L(CNRS-Ecole Polytechnique, Palaiseau).
时间：2016年6月17日（周五）上午10:00-11:00
地点：首都师范大学北一区文科楼708教室
欢迎全体师生积极参加！
