EXISTENCE OF LIMIT CYCLES FOR QUADRATIC SYSTEMS WITH ONE INFINITE SINGULAR POINT

摘要

This paper discusses the existence of limit cycles for quadratic systems with one infinite singular point. In particular, the author gives necessary anal sufficient conditions for the existence of a unique limit cycle of a class of quadratic systems with an integral line under certain conditions. As a special consequence, all the results of [-6] and [7] can be implied by means of affine transformations. The method used here is much simpler than those of [6] and [7].