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N. A. Soare 《Lithuanian Mathematical Journal》1997,37(3):287-290
In this note we consider structures defined on a differentiable manifoldM by a tensor fieldf of type (1,1) satisfying the conditionf
4+f
2=0 and by a Riemannian structureg such thatg(f(X),Y)=−g(Xf(Y)) for all vector fieldsX,YεT
1
0(M). Then we determine linear connections compatible with those structures.
Facultatea de Matematica, Str. Academiei 14, 70109 Bucaresti, Romania. Published in Lietuvos Matematikos Rinkinys, Vol. 37,
No. 3, pp. 383–387, July–September, 1997. 相似文献
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图的(g,f)-因子分解 总被引:1,自引:0,他引:1
设G是一个图,g(x)和f(x)是定义在图G的顶点集上的两个整数值函数且g≤f.图G的一个(g,f)-因子是G的一个支撑子图F使对任意的x∈V(F),有g(x)≤dF(x)≤f(x).如果图G的边集能划分为若干个边不相交的(g,f)-因子,则说图G是(g,f)-可因子化的.本文研究了图的(g,f)-可因子化的问题,给出了一个图G是(g,f)-可因子化的若干充分条件. 相似文献
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On(g,f)—Uniform Graphs 总被引:9,自引:0,他引:9
Thegraphsconsideredinthispaperwillbesimpleundirectedgraphs.LetGbeagraphwithvertexsetV(G)andedgesetE(G).ForavertexxofG,thedegreeofxinGisdenotedbydG(x).Theminimumdegreeandthemaximumdegree0fGaredenotedbyS(G)andb(G),respectively.Letgandfbetw0integer-valuedfunctionsdefined0nV(G)suchthatg(x)5f(x)foreveryx6V(G).Thena(g,f)-factorofGisaspanningsubgraphFofGsatisfyingg(x)SdF(x)5f(x)forallxEV(G).Ifg(x)=f(x)foreachxEV(G),thena(g,f)-factoriscalledanf-factor.Iffisaconstantfunctiontakingthevaluek,… 相似文献
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On (g, f)-Uniform Graphs 总被引:3,自引:0,他引:3
Gui-zhenLiu YanLiu 《应用数学学报(英文版)》2005,21(1):67-76
A graph G is called a (g, f)-uniform graph if for each edge of G, there is a (g, f)-factor containing it and another (g, f)-factor excluding it. In this paper a necessary and sufficient condition for a graph to be a (g, f)-uniform graph is given and some applications of this condition are discussed. In particular, some simple sufficient conditions for a graph to be an [a, b]-uniform graph are obtained for a≤b. 相似文献
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本文考虑的图 G 均为无环边的有限图.文中未定义的符号及术语均引自[1].对S,T(?)V(G),使得 S∩T=(?),我们用 E_G(S,T)表示 G 的端点分别包含在 S 及 T 中的边的集合.记 e_G(S,T)=|E_G(S,T)|. 相似文献
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设G是一个图,并设g和f是定义在V(G)上的整值函数使得对所有的点x∈ V(G)均有g(x)≤ f(x).称一个图G是(g,f,H) -可扩的,如果在删除了任意一个同构于H的子图中所有点后,剩下G的子图有一个(g,f) -因子.该文给出了(g,f,H) -可扩图的特征.进一步,研究了(g,f,H) -可扩(H=nK1)的性质. 相似文献
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若图的因子F的每一个分支都是完全图,则称F为完全-因子.本文研究了完全-因子F和(g,f)-对等图之间的关系,给出了有完全-因子F的图是(g,f)-对等图、f-对等图及k-对等图的关于F的分支的若干充分条件,并指出定理中的条件在一定意义上是最可能的,从而推广了李建湘等人的有关结果. 相似文献
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FRACTIONAL (g, f)-FACTORS OF GRAPHS 总被引:5,自引:0,他引:5
1 IntroductionThe graphs considered in this paper will be finite undirected graphs wllicll 11lay llavemultiple edges but no loops. Let G be a grapll with vertex set V(G) and edge set E(G). Fora vertex x of G, the degree of x in G is denoted by dG(z). Let g and f be two integer-valuedfunctions defined o11 V(G) such that 0 < g(z) 5 f(x) fOr all x E V(G). Then a (g, f)-factorof G is a spanning 8ubgraph F of G satisfying g(x) < dG(z) 5 f(x) for all x E V(F). Ifg(x) = f(x) for all x E V(… 相似文献
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图的分数(g,f)-因子 总被引:19,自引:0,他引:19
本文研究了图的分数因子的性质,特别给出了图的弧立韧度这一新概念,研究了孤立韧度与分数因子的关系,文中给出了一个图具有某些约束条件的(g,f)-分数因子的一些充分条件,得到了若干新结果,并提出 了一些可供进一步研究的问题。 相似文献
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关于(f,g)-因子定理的注记蔡茂诚(中国科学院系统科学研究所,北京100080)国家自然科学基金资助项目.1993年2月5日收到.我们只考虑有限的一般图,允许多重边和自环.一般图记作G=(V,E),其中V(G)是点集合,而E(G)是边集合.对于任意... 相似文献
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关于图的(g,f)-因子分解 总被引:9,自引:1,他引:8
设G是一个图,g和f是定义在图G的顶点集V(G)上的两个非负整数值函数且g<f.图G的一个(g,f)-因子是G的一个支撑子图F,使对所有的x∈V(G)有g(x)≤dF(x)≤f(x).若G本身是一个(g,f)-因子,则称G是一个(g,f)-图.若G的边能分解成一些边不交的(g,f)-因子,则称G是(g,f)-因子可分解的.本文给出图G是(g,f)-因子可分解的一个充分条件. 相似文献
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Pal Fischer 《Aequationes Mathematicae》1973,9(2-3):300-301
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我们给出了马欣荣的关于$(f, g)$-反演的三种应用. 在$(f, g)$-演中通过取具体的函数和序列, 我们推出了一些关于超几何级数与调和数的恒等式. 然后我们给出了一些关于$q$-超几何项的反演关系. 最后, 我们将$(f, g)$-反演和$q$-微分算子结合, 得到了一些$q$-级数恒等式. 相似文献
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1 IntroductionIn this paper we con8ider finite undirected simple graphs. Let G be a graph with vertexset V(G) and edge set E(G). Let g and f be two po8itive iuteger-valued functions defined onV(G) such that g(x) 5 f(x) for every vertex x of V(G). Then a (g, f)-factor of G is a spanningsubgraph H of G satisfying g(x) 5 dH(x) 5 f(x) for each x E V(H). In particular, if G itselfis a (g, f)-factor, then G is called a (g, f)-grapl1. A subgrapl1 H of G is called an rmsubgraphif H has m edg… 相似文献
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Let G be a multigraph, g and f be integer-valued functions defined on V(G). Then a graph G is called a (g, f)-graph if g(x)≤deg
G(x)≤f(x) for each x∈V(G), and a (g, f)-factor is a spanning (g, f)-subgraph. If the edges of graph G can be decomposed into (g, f)-factors, then we say that G is (g, f)-factorable. In this paper, we obtained some sufficient conditions for a graph to be (g, f)-factorable. One of them is the following: Let m be a positive integer, l be an integer with l=m (mod 4) and 0≤l≤3. If G is an -graph, then G is (g, f)-factorable. Our results imply several previous (g, f)-factorization results.
Revised: June 11, 1998 相似文献
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图的(g,f)-因子和因子分解 总被引:17,自引:0,他引:17
设G是一个图,g,f是定义在图G的顶点集上的两个整数值函数且图G的一个(g,f)-因子是G的一个支撑子图F使对任意的x∈V(F)有本文给出了一个图(g,f)-可因子化的若干充分条件和一个图是(g,f)-消去图的充分必要条件,并研究了这些条件的应用。 相似文献
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The vertex set of the reduced Kneser graph KG2(m,2) consists of all pairs {a,b} such that a, bε{1,2,…,m} and 2≤|a?b|≤m?2. Two vertices are defined to be adjacent if they are disjoint. We prove that, if m≥4 and m≠5, then the circular chromatic number of KG2(m,2) is equal to m?2, its ordinary chromatic number. © 2002 Wiley Periodicals, Inc. J Graph Theory 41: 62–68, 2002 相似文献
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