Bifurcations of small limit cycles in Liénard systems with cubic restoring terms.

In this paper, we study bifurcations of small-amplitude limit cycles of Liénard systems of the form x ˙ = y − F (x) , y ˙ = − g (x) , where g (x) is a cubic polynomial, and F (x) is a smooth or piecewise smooth polynomial of degree n. By using involutions, we obtain sharp upper bounds of the number of small-amplitude limit cycles produced around a singular point for some systems of this type. [ABSTRACT FROM AUTHOR]