A polynomial differential system with nine limit cycles at infinity
In this article, we give a recursive formula to compute the singular point quantities of a class of seventh-order polynomial systems. The first eleven singular point quantities have been computed with computer algebra system Mathematica, and the conditions for infinity to be a center have been deduced as well. At last, we construct a system that allows the appearance of nine limit cycles in the neighborhood of infinity. (C) 2004 Elsevier Ltd. All rights reserved.
infinity singular point quantity focal value center condition bifurcation of limit cycles