One Upper Estimate on the Number of Limit Cycles of Even Degree Liénard Equations in the Focus Case

Abstract

We give an explicit upper bound for a number of limit cycles of the Liénard equation $\dot{x}=y-F(x)$, $\dot{y}=-x$ of even degree in the case its unique singular point $(0,0)$ is a focus.

arXiv comment10 pages, 1 figure