On the uniqueness of limit cycles for Liénard equations: the legacy of G. Sansone

Abstract

We give an account of the results about limit cycle’s uniqueness for Liénard equations, starting from Levinson-Smith’s one to the most recent ones. We present a new uniqueness theorem in the line of Sansone-Massera’s geometrical approach.

Keywords

• Liénard equation
• Sansone
• Massera
• uniqueness
• limit cycle.