In this paper, we obtain some estimations of the saddle order which is the sole topological invariant of the non-integrable resonant saddles of planar polynomial vector fields of arbitrary degree $n$. Firstly, we prove that, for any given resonance $p:-q$, $(p, q)=1$, and sufficiently big integer $n$, the maximal saddle order can grow at least as rapidly as $n^2$. Secondly, we show that there exists an integer $k_0$, which grows at least as rapidly as $3n^2/2$, such that $L_{k_0}$ does not belong to the ideal generated by the first $k_0-1$ saddle values $L_1, L_2, \cdots, L_{k_0-1}$, where $L_{k}$ represents the $k$-th saddle value of the given system. In particular, if $p=1$ (or $q=1$), we obtain a sharper result that $k_0$ can grow at least as rapidly as $2 n^2$. These results are valid for both cases of real and complex resonant saddles.
Citation: |
[1] |
J. Bai and Y. Liu, A class of planar degree n (even number) polynomial systems with a fine focus of order $n^2-n$, Chinese Sci. Bull., 12 (1992), 1063–1065 (in Chinese).
![]() |
[2] |
N. N. Bautin, On the number of limit cycles which appear with the variation of coefficients from an equilibrium position of focus or center type, Math. USSR Sb., 100 (1954), 397-413.
![]() ![]() |
[3] |
Y. N. Bibikov, Local Theory of Nonlinear Analytic Ordinary Differential Equations, Lecture Notes in Mathematics, 702, Springer-Verlag, New York, 1979.
![]() ![]() |
[4] |
C. Camacho and P. Sad, Topological classification and bifurcations of holomorphic flows with resonances in $\mathbb{C}^2$, Invent. math., 67 (1982), 447-472.
doi: 10.1007/BF01398931.![]() ![]() ![]() |
[5] |
X. Chen, J. Giné, V. G. Romanovski and D. S. Shafer, The $1: -q$ resonant center problem for certain cubic Lotka-Volterra systems, Appl. Math. Comput., 218 (2012), 11620-11633.
doi: 10.1016/j.amc.2012.05.045.![]() ![]() ![]() |
[6] |
D. Dolićanin, J. Giné, R. Oliveira and V. G. Romanovski, The center problem for a 2:-3 resonant cubic Lotka-Volterra system, Appl. Math. Comput., 220 (2013), 12-19.
doi: 10.1016/j.amc.2013.06.007.![]() ![]() ![]() |
[7] |
G. Dong, C. Liu and J. Yang, The complexity of generalized center problem, Qual. Theory Dyn. Syst., 14 (2015), 11-23.
doi: 10.1007/s12346-015-0131-6.![]() ![]() ![]() |
[8] |
G. Dong and J. Yang, On the saddle order of polynomial differential systems at a resonant singular point, J. Math. Anal. Appl., 423 (2015), 1557-1569.
doi: 10.1016/j.jmaa.2014.10.085.![]() ![]() ![]() |
[9] |
M. Dukarić, B. Ferčec and J. Giné, The solution of the $1:-3$ resonant center problem in the quadratic case, Appl. Math. Comput., 237 (2014), 501-511.
doi: 10.1016/j.amc.2014.03.147.![]() ![]() ![]() |
[10] |
B. Ferčec, X. Chen and V. G. Romanovski, Intergrability conditions for complex systems with homogeneous quintic nonlinearities, J. Appl. Anal. Comput., 1 (2011), 9-20.
![]() ![]() |
[11] |
B. Ferčec, J. Giné, M. Mencinger and R. Oliveira, The center problem for a 1:-4 resonant quadratic system, J. Math. Anal. Appl., 420 (2014), 1568-1591.
doi: 10.1016/j.jmaa.2014.06.060.![]() ![]() ![]() |
[12] |
A. Fronville, A. Sadovski and H. Zoladek, Solution of the $1:-2$ resonant center problem in the quadratic case, Fund. Math., 157 (1998), 191-207.
![]() ![]() |
[13] |
J. Giné, Higher order limit cycle bifurcations from non-degenerate centers, Appl. Math. Comput., 218 (2012), 8853-8860.
doi: 10.1016/j.amc.2012.02.044.![]() ![]() ![]() |
[14] |
J. Giné and J. Llibre, Integrability conditions of a resonant saddle in generalized Liénard-like complex polynomial differential systems, Chaos Solitons Fractals, 96 (2017), 130-131.
doi: 10.1016/j.chaos.2017.01.014.![]() ![]() ![]() |
[15] |
J. Giné and C. Valls, Integrability conditions for complex kukles systems, Dyn. Syst., 32 (2017), 211-220.
doi: 10.1080/14689367.2016.1181715.![]() ![]() ![]() |
[16] |
J. Giné and C. Valls, Integrability conditions of a resonant saddle perturbed with homogeneous quintic nonlinearities, Nonlinear Dynam., 81 (2015), 2021-2030.
doi: 10.1007/s11071-015-2122-1.![]() ![]() ![]() |
[17] |
Z. Hu, V. G. Romanovski and D. S. Shafer, $1:-3$ resonant center on $\mathbb{C}^{2}$ with homogeneous cubic nonlinearities, Comput. Math. Appl., 56 (2008), 1927-1940.
doi: 10.1016/j.camwa.2008.04.009.![]() ![]() ![]() |
[18] |
J. Huang, F. Wang, L. Wang and J. Yang, A quartic system and a quintic system with fine focus of order 18, Bull. Sci. Math., 132 (2008), 205-217.
doi: 10.1016/j.bulsci.2006.12.006.![]() ![]() ![]() |
[19] |
Y. S. Ilyashenko and A. S. Pyartli, Materialization of resonances and divergence of normalizing series for polynomial differential equations, J. Sov. Math., 32 (1986), 300-313.
doi: 10.1007/BF01106073.![]() ![]() |
[20] |
P. Joyal and C. Rousseau, Saddle quantities and applications, J. Differential Equations, 78 (1989), 374-399.
doi: 10.1016/0022-0396(89)90069-7.![]() ![]() ![]() |
[21] |
H. Liang and J. Torregrosa, Parallelization of the Lyapunov constants and cyclicity for centers of planar polynomial vector fields, J. Differential Equations, 259 (2015), 6494-6509.
doi: 10.1016/j.jde.2015.07.027.![]() ![]() ![]() |
[22] |
H. Liang and J. Torregrosa, Weak-foci of high order and cyclicity, Qual. Theory Dyn. Syst., 16 (2017), 235-248.
doi: 10.1007/s12346-016-0189-9.![]() ![]() ![]() |
[23] |
C. Liu and Y. Li, The integrability of a class of cubic Lotka-Volterra systems, onlinear Anal. Real World Appl., 19 (2014), 67-74.
doi: 10.1016/j.nonrwa.2014.02.007.![]() ![]() ![]() |
[24] |
Y. Liu and J. Li, Theory of values of singular point in complex autonomous differential systems, Sci. China Ser. A, 33 (1990), 10-23.
![]() ![]() |
[25] |
Y. Qiu and J. Yang, On the focus order of planar polynomial differential equations, J. Differential Equations, 246 (2009), 3361-3379.
doi: 10.1016/j.jde.2009.02.005.![]() ![]() ![]() |
[26] |
V. G. Romanovski and D. S. Shafer, On the center problem for $p:-q$ resonant polynomial vector fields, Bull. Belg. Math. Soc. Simon Stevin, 15 (2008), 871-887.
![]() ![]() |
[27] |
A. P. Sadovskii, Center and foci for a class of cubic systems, Differ. Equ., 36 (2000), 1812-1818.
doi: 10.1023/A:1017552612453.![]() ![]() ![]() |
[28] |
K. S. Sibirskii, Introduction to the Algebraic Theory of Invariants of Differential Equations, Manchester University Press, Manchester, 1988.
![]() ![]() |
[29] |
P. Yu and Y. Tian, Twelve limit cycles around a singular point in a planar cubic-degree polynomial system, Commun. Nonlinear Sci. Numer. Simulat., 19 (2014), 2690-2705.
doi: 10.1016/j.cnsns.2013.12.014.![]() ![]() ![]() |
[30] |
H. Zoladek, The problem of center for resonant singular points of polynomials vector fields, J. Differential Equations, 137 (1997), 94-118.
doi: 10.1006/jdeq.1997.3260.![]() ![]() ![]() |