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1.
本文首先讨论了一类食饵一捕食系统的稳定性,并运用Dulac函数法,给出该系统不存在极限环的充分条件.然后运用Hopf分支问题的Liapunov第二方法研究了雌寄生蜂一寄主生态系统存在稳定的极限环的条件。 相似文献
2.
In this paper, the generalized synchronization of two unidirectionally coupled Ginzburg-Landau equations is studied theoretically. It is demonstrated that the drive-response system has bounded attraction domain and compact attractors. It is derived that the correction equation has asymptotically stable zero solutions under certain conditions and that the sufficient conditions for smooth generalized synchronization and Hölder continuous generalized synchronization exist in the coupling system. Numerical result analysis shows the correctness of theory. 相似文献
3.
1991年刘振宏和李明楚在南京大学召开的首届哈密顿图研讨会的综述文章中说"要给出一个一般图具有哈密顿圈的充分条件是一件非常不容易的事"。因哈密顿图是含哈密顿圈的图类,如此哈密顿图主要有六个方向:哈密顿圈、哈密顿连通、泛圈图、点泛圈图、泛连通图、最短路径泛圈图。本文中,我们就给出一般图的这些领域新进展的小综述。 相似文献
4.
Thompson’s theorem indicates that a finite group with a nilpotent maximal subgroup of odd order is solvable. As an important
application of Thompson’s theorem, a finite group is solvable if it has an abelian maximal subgroup. In this paper, we give
some sufficient conditions on the number of non-abelian subgroups of a finite group to be solvable. 相似文献
5.
Shangquan BU 《数学年刊B辑(英文版)》2011,32(2):293-302
The author establishes operator-valued Fourier multiplier theorems on multi-dimensional Hardy spaces H
p
($
\mathbb{T}
$
\mathbb{T}
d
;X), where 1 ≤ p < ∞, d ∈ ℕ, and X is an AUMD Banach space having the property (α). The sufficient condition on the multiplier is a Marcinkiewicz type condition of order 2 using Rademacher boundedness of
sets of bounded linear operators. It is also shown that the assumption that X has the property (α) is necessary when d ≥ 2 even for scalar-valued multipliers. When the underlying Banach space does not have the property (α), a sufficient condition on the multiplier of Marcinkiewicz type of order 2 using a notion of d-Rademacher boundedness is also given. 相似文献
6.
In this paper, we show the following result: Let K
i
be a knot in a closed orientable 3-manifold M
i
such that (M
i
,K
i
) is not homeomorphic to (S
2 ×S
1, x
0 ×S
1), i = 1, 2. Suppose that the Euler Characteristic of any meridional essential surface in each knot complement E(K
i
) is less than the difference of one and twice of the tunnel number of K
i
. Then the tunnel number of their connected sum will not go down. If in addition that the distance of any minimal Heegaard
splitting of each knot complement is strictly more than 2, then the tunnel number of their connected sum is super additive. 相似文献
7.
For the planar Z
2-equivariant cubic systems having two elementary focuses, the characterization of a bi-center problem and shortened expressions
of the first six Liapunov constants are completely discussed. The necessary and sufficient conditions for the existence of
the bi-center are obtained. All possible first integrals are given. Under small Z
2-equivariant cubic perturbations, the conclusion that there exist at most 12 small-amplitude limit cycles with the scheme
〈6 ∐ 6〉 is proved. 相似文献
8.
The relationships between piecewise-Koszul algebras and other “Koszul-type” algebras are discussed. The Yoneda-Ext algebra
and the dual algebra of a piecewise-Koszul algebra are studied, and a sufficient condition for the dual algebra A
! to be piecewise-Koszul is given. Finally, by studying the trivial extension algebras of the path algebras of Dynkin quivers
in bipartite orientation, we give explicit constructions for piecewise-Koszul algebras with arbitrary “period” and piecewise-Koszul
algebras with arbitrary “jump-degree”. 相似文献
9.
10.
Jie Ming Wang 《数学学报(英文版)》2009,25(5):741-758
The stochastic comparison and preservation of positive correlations for Levy-type processes on R^d are studied under the condition that Levy measure v satisfies f{0〈|z|≤1)|z||v(x, dz) - v(x, d(-z))| 〈 ∞, x∈ R^d, while the sufficient conditions and necessary ones for them are obtained. In some cases the conditions for stochastic comparison are not only sufficient but also necessary. 相似文献