SEVEN LARGE-AMPLITUDE LIMIT CYCLES IN A CUBIC POLYNOMIAL SYSTEM.

In this paper, the problem of limit cycles bifurcated from the equator for a cubic polynomial system is investigated. The best result so far in the literature for this problem is six limit cycles. By using the method of singular point value, we prove that a cubic polynomial system can bifurcate seven limit cycles from the equator. We also find that a rational system has an isochronous center at the equator. [ABSTRACT FROM AUTHOR]