科研之友
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摘要
We study the problem of formal classification of the vector fields of the form (x) over dot = ax(2) + bxy + cy(2) + ..., (y) over dot = dx(2) + exy + fy(2) + ... using formal changes of the coordinates, but not using the changes of the time. We focus on one special case (which is the most complex one): when the quadratic homogeneous part has a polynomial first integral. In the proofs we avoid complicated calculations. The method we use is effective and it is based on the method introduced in our previous work concerning the Bogdanov Takens singularity.
- 出版日期2015-12-5
