On the existence of at most 2 limit cycles surrounding multiple singular points for Liénard equation. (Chinese. English summary) Zbl 0768.34016
Summary: Some useful results in estimating the integral of the divergence are improved: It follows that some sufficient conditions for the Liénard equation are obtained which guarantee the existence of at most 2 limit cycles surrounding multiple singular points.
MSC:
| 34C05 | Topological structure of integral curves, singular points, limit cycles of ordinary differential equations |
