Abstract

My talk primarily consists of two parts: In the first part, I will present a kind of polynomial differential systems of degree $n$ ($n$ even) which can have as high as $n2-n$ degree of fine focus. In this second part of the talk, I will show that there are quartic systems and quintic systems, resp. (i.e.,linear center plus homogeneous degree 4 and 5 nonlinearity, resp.) which can have an order 18 of fine focus.