随机有向循环图的连通度

In this paper, we prove that almost all circulant digraphs are strongly connected. Furthermore, for any given positive integer m, we show that almost every circulant digraph C has connectivity at least m/1 m(d(C) 1), where d(C) is the vertex degree of C.     

有向循环图的同构

Let S belong to Zn-{0}.The circulant digraph DCn(S) is a directed graph with vertex set Zn and are set {(i,i s):i∈Zn,s∈S},A.Adam conjectured that DCn(S)≌DCn(T) if and only if T=uS for some unit u mod n.In this paper we prove that the conjecture is true if S is a minimal generating set of Zn and thus determine the full automorphism groups of such digraphs.The methods we employ are new and easy to be understood.     

有向循环图的支撑树数

设k≥2,1≤a_1相似文献   

结构VAR的有向非循环图模型

研究用图模型方法辨识结构向量自回归(VAR)模型,图中的结点表示不同时刻的随机变量,结点间的边表示其所表示的随机变量之间存在的因果相依关系.针对建立有向非循环图的问题,提出了一种基于回归分析的判断方法,用回归方程的回归平方和之差作为统计量,确定当前变量之间相依关系的方向.与R ea le的逐一判别法和A lessio的图搜索方法相比,文中提出的基于统计分析的方法简单易行,且可获得唯一的当前变量有向非循环图.最后以两组模拟序列为例,验证了所提出的方法是可行且有效的.     

6个素数阶完全图的循环图分解

研究素数阶完全图分解为循环图的方法 ,给出计算它的子图的团数的一种算法 ,得到 3个三色 ,3个四色 Ramsey数的新的下界 :R(3,3,13) 194 ,R(3,4 ,11) 2 12 ,R(3,6 ,13) 52 2 ,R(3,3,4 ,10 ) 380 ,R(3,3,6 ,14) 1154,R(3,4 ,5,13) 10 94     

有向循环图强连通度的下界

为简便计,本文采用文[1]中的定义和符号,而未说明的概念或符号引自[3].本文仅讨论有限、简单有向图. 有向图D=(V,A)称为强连通的,如果对D的任两顶点u与v,在D中同时存在(u,v)—有向路和(v,u)—有向路,C(?)V称为D的点割集,如果D—C非强连通或是单点.D的所含点数最少的点割集称为最小点割集,其阶数定义为D的强连通度,记为k(D)或k. 循环有向图D(n,S)定义如下:     

循环图能量的一个上界

本文讨论循环图的能量,得到循环图能量上界的一个估计值.进一步得到整循环图能量的两个计算公式.     

循环图的Adam同构的性质

本文得到了任意两个连通循环图是(?)d(?)m同构的充要条件,并且还得到两个连通循环图是(?)d(?)m同构的另一必要条件。     

循环图的连通度

设Ｇ＝Ｇｎ（ｉ１,ｉ２,…,ｉｒ）是连通循环图,且ｘ（Ｇ）〈δ（Ｇ）,本文得到了其连通度的明确表达式：ｘ（Ｇ）＝ｍｉｎ（ｍ／Ｍ（ｎ／ｍ,Ｋ）／：ｍ是ｎ的真因子,且／Ｍ（ｎ／ｍ,Ｋ）／〈ｎ／ｍ－１）。     

Infinite Circulant Digraphs and Random Infinite Circulant Digraphs

In this paper, we completely determine the connectivity of every infinite circulant digraphs and prove that almost all infinite circulant digraphs are infinitely strongly connected and therefore have both one- and two-way infinite Hamiltonian paths. Received February 4, 1998, Accepted May 16, 2002     

对换网络和乘积循环网络的超连通性

本文证明了对换网络和乘积循环网络是超连通的。     

顺序和顺序哈密顿有向图

A digraph D is k-ordered if for every sequence S:v 1,v 2,…,v k of k distinct vertices,there exists a cycle C such that C encounters the vertices of S in the specified order.In particular,we say that D is k-ordered hamiltonian if for every sequence S:v 1,v 2,…,v k of k distinct vertices,there exists a hamiltonian cycle C such that the vertices of S are encountered on C in the specified order.In this paper,sufficient conditions for digraphs to be ordered and ordered hamiltonian have been given.     

Rainbow Arborescence in Random Digraphs

We consider the Erd?s–Rényi random directed graph process, which is a stochastic process that starts with n vertices and no edges, and at each step adds one new directed edge chosen uniformly at random from the set of missing edges. Let be a graph with m edges obtained after m steps of this process. Each edge () of independently chooses a color, taken uniformly at random from a given set of colors. We stop the process prematurely at time M when the following two events hold: has at most one vertex that has in‐degree zero and there are at least distinct colors introduced ( if at the time when all edges are present there are still less than colors introduced; however, this does not happen asymptotically almost surely). The question addressed in this article is whether has a rainbow arborescence (i.e. a directed, rooted tree on n vertices in which all edges point away from the root and all the edges are different colors). Clearly, both properties are necessary for the desired tree to exist and we show that, asymptotically almost surely, the answer to this question is “yes.”     

Sufficient Conditions for Maximally Edge-connected and Super-edge-connected Digraphs Depending on the Size

Let D be a finite and simple digraph with vertex set V (D). The minimum degree δ of a digraph D is defined as the minimum value of its out-degrees and its in-degrees. If D is a digraph with minimum degree δ and edge-connectivity λ, then λ ≤ δ. A digraph is maximally edge-connected if λ=δ. A digraph is called super-edge-connected if every minimum edge-cut consists of edges incident to or from a vertex of minimum degree. In this note we show that a digraph is maximally edge-connected or super-edge-connected if the number of arcs is large enough.     

Super Connectivity of Line Graphs and Digraphs

The h-super connectivity κh and the h-super edge-connectivity λh are more refined network reliability indices than the conneetivity and the edge-connectivity. This paper shows that for a connected balanced digraph D and its line digraph L, if D is optimally super edge-connected, then κ1（L） = 2λ1 （D）, and that for a connected graph G and its line graph L, if one of κ1 （L） and λ（G） exists, then κ1（L） = λ2（G）. This paper determines that κ1（B（d, n） is equal to 4d- 8 for n = 2 and d ≥ 4, and to 4d-4 for n ≥ 3 and d ≥ 3, and that κ1（K（d, n）） is equal to 4d- 4 for d 〉 2 and n ≥ 2 except K（2, 2）. It then follows that B（d,n） and K（d, n） are both super connected for any d ≥ 2 and n ≥ 1.     

Supereulerian Digraphs with Large Arc‐Strong Connectivity

Let D be a digraph and let be the arc‐strong connectivity of D, and be the size of a maximum matching of D. We proved that if , then D has a spanning eulerian subdigraph.     

An infinite family of 4-tight optimal double loop networks

An infinite family of 4-tight optimal double loop networks is given in this paper.     

循环圈的连通度

设G＝C_n（i₁,i₂,…,i_r）是连通循环圈,且k（G）＜δ（G）．本文得到了其连通度的明确表达式κ(G)=min{m|M(n/m,K)|:m是n的真因子,且|M(n/m,K)|相似文献