PERIODIC SOLUTIONS FOR LIÉNARD DIFFERENTIAL EQUATIONS WITH SINGULARITIES.

In this article, we study the second-order forced Liínard equation x" + f(x)x' + g(x) = e(t). By using the topological degree theory, we prove that the equation has at least one positive periodic solution when g admits a repulsive singularity near the origin and satisfies some semilinear growth conditions near infinity. Recent results in the literature are generalized and complemented. [ABSTRACT FROM AUTHOR]