NON-EXISTENCE OF LIMIT CYCLE AROUND A WEAK FOCUS OF ORDER THREE FOR ANY QUADRATIC SYSTEM
Citation：
Li Chengzhi.NON-EXISTENCE OF LIMIT CYCLE AROUND A WEAK FOCUS OF ORDER THREE FOR ANY QUADRATIC SYSTEM[J].Chinese Annals of Mathematics B,1986,7(2):174~190
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Authors：
Li Chengzhi;
Foundation：
This paper has been read in The Fourth International Symposium on Differential Equations and Differential Geometry (1983, Beijing).
Abstract：
In 1980 Professor Ye Yangian proposed a conjecture that around a weak focus of order 3 of any real quadratic differential system there can exist no limit cycle. It is the purpose of this paper to give a proof of the conjecture by using the method of continuous variation of a coefficient.
