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991.
992.
Hongxia Ma & Juan Liu 《数学研究通讯:英文版》2016,32(4):332-338
Let γ*(D) denote the twin domination number of digraph D and let D_1 D_2 denote the strong product of D_1 and D_2. In this paper, we obtain that the twin domination number of strong product of two directed cycles of length at least 2.Furthermore, we give a lower bound of the twin domination number of strong product of two digraphs, and prove that the twin domination number of strong product of the complete digraph and any digraph D equals the twin domination number of D. 相似文献
993.
Dušan Repovš Witold Rosicki Žiga Virk Andreas Zastrow 《Topology and its Applications》2012,159(10-11):2609-2620
This paper shows that a construction, which was introduced by Piotr Minc in connection with a problem that came from Helly type theorems and that allows to replace three PL-arcs with a “sheltered middle path”, can in the case of general (non-PL) paths result in the topologist?s sine curve. 相似文献
994.
We prove that n pairwise commuting derivations of the polynomial ring (or the power series ring) in n variables over a field k of characteristic 0 form a commutative basis of derivations if and only if they are k-linearly independent and have no common Darboux polynomials. This result generalizes a recent result due to Petravchuk and is an analogue of a well-known fact that a set of pairwise commuting linear operators on a finite dimensional vector space over an algebraically closed field has a common eigenvector. 相似文献
995.
Let G be a graph with n vertices and edges, and let be the Laplacian eigenvalues of G. Let , where . Brouwer conjectured that for . It has been shown in Haemers et al. [7] that the conjecture is true for trees. We give upper bounds for , and in particular, we show that the conjecture is true for unicyclic and bicyclic graphs. 相似文献
996.
We discuss heteroclinic bifurcation in a class of periodically excited planar piecewise smooth systems with discontinuities on finitely many smooth curves intersecting at the origin. Assume that the unperturbed system has a hyperbolic saddle in each subregion, and those saddles are connected by a heteroclinic cycle that crosses every switching curve transversally exactly once. We present a method of Melnikov type to derive sufficient conditions under which the perturbed stable and unstable manifolds intersect transversally. Such transversal intersections imply that the corresponding Poincaré map has a transverse heteroclinic cycle. As applications, we present examples with 2 and 4 switching curves respectively. Our numerical simulations suggest that such transversal intersections result in the appearance of chaotic motions in those example systems. 相似文献
997.
998.
在完备可分的半序度量空间中,引入了随机映射对(F,G)关于g随机半序弱增以及(F,G)随机半序弱增的定义,研究了在满足一定非线性压缩条件下的随机映射列F_k:Ω×X×X→X,k=1,2…,g:Ω×X→X和h:Ω×X→X的公共二元随机重合点与公共二元随机不动点问题,所得结果推广了已有文献中的一些不动点定理. 相似文献
999.
D. Zeidan In this paper, we consider the existence of traveling waves in a generalized nonlinear dispersive–dissipative equation, which is found in many areas of application including waves in a thermoconvective liquid layer and nonlinear electromagnetic waves. By using the theory of dynamical systems, specifically based on geometric singular perturbation theory and invariant manifold theory, Fredholm theory, and the linear chain trick, we construct a locally invariant manifold for the associated traveling wave equation and use this invariant manifold to obtain the traveling waves for the nonlinear dispersive–dissipative equation. Copyright © 2015 John Wiley & Sons, Ltd. 相似文献
1000.
Richard De la cruz Juan Galvis Juan Carlos Juajibioy Leonardo Rendón 《Bulletin of the Brazilian Mathematical Society》2016,47(1):277-290
We study the one-dimensional Riemann problem for a hyperbolic system of three conservation laws of Temple class. The system is a simplification of a recently proposed system of five conservations laws by Bouchut and Boyaval that models viscoelastic fluids. An important issue is that the considered 3×3 system is such that every characteristic field is linearly degenerate. We study theRiemann problemfor this system and under suitable generalized Rankine-Hugoniot relation and entropy condition, both existence and uniqueness of particular delta shock type solutions are established. 相似文献