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On the conditions of Kukles for the existence of a Centre
Author(s) -
Jin Xiaofan,
Wang Dongming
Publication year - 1990
Publication title -
bulletin of the london mathematical society
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 2.396
H-Index - 48
eISSN - 1469-2120
pISSN - 0024-6093
DOI - 10.1112/blms/22.1.1
Subject(s) - mathematics , pure mathematics
For a class of cubic differential systems, Kukles established necessary and sufficient conditions for the existence of a centre. This paper presents a particular system that shows that either Kukles' conditions are incomplete, or the multiplicity of the origin as a focus is greater than or equal to 9.