共查询到20条相似文献,搜索用时 93 毫秒
1.
王丽 《数学的实践与认识》2012,42(1):234-241
称一个有限简单无向图X是半对称图,如果图X是正则的且边传递但非点传递.主要利用仿射几何构造了一类2p~n阶连通p~3。度的半对称图的无限族,其中p≥n≥8. 相似文献
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目的是研究局部传递图的性质和分类.运用置换群和陪集图的理论,获得了关于素数立方阶群局部传递图的完全分类,证明了这些图是一些互不相交的关于素数立方阶群边传递图的并. 相似文献
3.
王丽 《数学的实践与认识》2011,41(10)
称一个有限简单无向图X是半对称图,如果图X是正则的且边传递但非点传递.本文主要利用仿射几何构造了一类2p~n阶连通p~2度的半对称图的无限族,其中p≥n≥5. 相似文献
4.
图X是一个有限简单无向图,如果图X是正则的且边传递但非点传递,则称X是半对称图.主要利用仿射几何构造了一类2p~n阶连通p~4度的半对称图的无限族,其中p≥n≥11. 相似文献
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关于半传递图的若干新结果 总被引:1,自引:0,他引:1
我们称无向图X为半传递的,如果它的自同构群Aut X在X的顶点集合以及边集合上作用是传递的,但在X的有序的相邻顶点对的集合上作用非传递。本文综述了自1990年以来若干数学家包括作者本人在半传递图方面研究的最新结果,特别地,我们的工到了具有本原自同构群的半传递图,从而肯定地回答了Holton问题,同时还证明了只存在一个4度27阶的半传递图,解决了Holt问题。 相似文献
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2-弧传递图是对称图类的一个重要的子类,而拟本原和双拟本原的2-弧传递图在2-弧传递图的研究中具有最基本的意义.文中对阶为kp^m(k,p是素数,k≠p,m≥2是整数)的基本2-孤传递图进行了研究。获得了下列结果:(1)kp^m阶G-拟本原的2-弧传递图是几乎单的.(2)对2p^m阶和2^mk阶双拟本原的2-弧传递图的分类进行了刻划,确定了其自同构群的基柱. 相似文献
9.
王福荣 《数学的实践与认识》2006,36(4):260-265
如果一个正则图是边传递但不是点传递的,那么我们称它是半对称的.每一个半对称图X必定是两部分点数相等的二部图,并且它的自同构群Aut(X)在每一部分上是传递的.如果一个半对称图的自同构群在每一部分上作用是本原的,那么我们称它是双本原的.本文决定了第二小阶数的双本原半对称图. 相似文献
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图Γ称为点传递自补图,如果Γ的图自同构群AutΓ在顶点集合VΓ作用是传递的,且Γ的补图(Γ)与图Γ是同构的.本文主要研究了通过Cayley同构来构造点自补Cayley图,并证明了内循环群上的这类图必然是循环自补图. 相似文献
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A simple undirected graph is said to be semisymmetric if it is regular and edge-transitive but not vertex-transitive. Let
p be a prime. It was shown by Folkman (J. Combin. Theory
3 (1967) 215–232) that a regular edge-transitive graph of order 2p or 2p
2 is necessarily vertex-transitive. In this paper, an extension of his result in the case of cubic graphs is given. It is proved
that, every cubic edge-transitive graph of order 8p is symmetric, and then all such graphs are classified. 相似文献
12.
Richard Hammack Wilfried Imrich Sandi Klavžar 《Journal of Algebraic Combinatorics》2016,43(4):837-850
This paper concerns finite, edge-transitive direct and strong products, as well as infinite weak Cartesian products. We prove that the direct product of two connected, non-bipartite graphs is edge-transitive if and only if both factors are edge-transitive and at least one is arc-transitive, or one factor is edge-transitive and the other is a complete graph with loops at each vertex. Also, a strong product is edge-transitive if and only if all factors are complete graphs. In addition, a connected, infinite non-trivial Cartesian product graph G is edge-transitive if and only if it is vertex-transitive and if G is a finite weak Cartesian power of a connected, edge- and vertex-transitive graph H, or if G is the weak Cartesian power of a connected, bipartite, edge-transitive graph H that is not vertex-transitive. 相似文献
13.
Cai Heng Li 《Journal of Algebraic Combinatorics》2008,28(2):261-270
We characterize the automorphism groups of quasiprimitive 2-arc-transitive graphs of twisted wreath product type. This is
a partial solution for a problem of Praeger regarding quasiprimitive 2-arc transitive graphs. The solution stimulates several
further research problems regarding automorphism groups of edge-transitive Cayley graphs and digraphs.
This work forms part of an ARC grant project and is supported by a QEII Fellowship. 相似文献
14.
Robert E. Jamison characterized chordal graphs by the edge set of every k-cycle being the symmetric difference of k−2 triangles. Strongly chordal (and chordal bipartite) graphs can be similarly characterized in terms of the distribution of triangles (respectively, quadrilaterals). These results motivate a definition of ‘strongly chordal bipartite graphs’, forming a class intermediate between bipartite interval graphs and chordal bipartite graphs. 相似文献
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Motivated from an example of ridge graphs relating to metric polytopes, a class of connected regular graphs such that the squares of their adjacency matrices are in certain symmetric Bose-Mesner algebras of dimension 3 is considered in this paper as a generalization of strongly regular graphs. In addition to analysis of this prototype example defined over (MetP5)*, some general properties of these graphs are studied from the combinatorial view point.AMS Subject Classification: 05E30. 相似文献
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Many large graphs can be constructed from existing smaller graphs by using graph operations, for example, the Cartesian product and the lexicographic product. Many properties of such large graphs are closely related to those of the corresponding smaller ones. In this short note, we give some properties of the lexicographic products of vertex-transitive and of edge-transitive graphs. In particular, we show that the lexicographic product of Cayley graphs is a Cayley graph. 相似文献
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Marston Conder Aleksander Malnič Dragan Marušič Primž Potočnik 《Journal of Algebraic Combinatorics》2006,23(3):255-294
A list is given of all semisymmetric (edge- but not vertex-transitive) connected finite cubic graphs of order up to 768. This
list was determined by the authors using Goldschmidt's classification of finite primitive amalgams of index (3,3), and a computer
algorithm for finding all normal subgroups of up to a given index in a finitely-presented group. The list includes several
previously undiscovered graphs. For each graph in the list, a significant amount of information is provided, including its
girth and diameter, the order of its automorphism group, the order and structure of a minimal edge-transitive group of automorphisms,
its Goldschmidt type, stabiliser partitions, and other details about its quotients and covers. A summary of all known infinite
families of semisymmetric cubic graphs is also given, together with explicit rules for their construction, and members of
the list are identified with these. The special case of those graphs having K1,3 as a normal quotient is investigated in detail.
Supported in part by N.Z. Marsden Fund (grant no. UOA 124) and N.Z. Centres of Research Excellence Fund (grant no. UOA 201)
Supported in part by “Ministrstvo za šolstvo, znanost in šport Slovenije”, research program no. 101-506.
Supported in part by research projects no. Z1-4186-0101 and no. Z1-3124-0101. The fourth author would like to thank the University
of Auckland for hospitality during his visit there in 2003. 相似文献
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A graph is called edge-transitive if its full automorphism group acts transitively on its edge set.In this paper,by using classification of finite simple groups,we classify tetravalent edge-transitive graphs of order p2q with p,q distinct odd primes.The result generalizes certain previous results.In particular,it shows that such graphs are normal Cayley graphs with only a few exceptions of small orders. 相似文献
20.
A 2-join is an edge cutset that naturally appears in decomposition of several classes of graphs closed under taking induced subgraphs, such as perfect graphs and claw-free graphs. In this paper we construct combinatorial polynomial time algorithms for finding a maximum weighted clique, a maximum weighted stable set and an optimal coloring for a class of perfect graphs decomposable by 2-joins: the class of perfect graphs that do not have a balanced skew partition, a 2-join in the complement, nor a homogeneous pair. The techniques we develop are general enough to be easily applied to finding a maximum weighted stable set for another class of graphs known to be decomposable by 2-joins, namely the class of even-hole-free graphs that do not have a star cutset.We also give a simple class of graphs decomposable by 2-joins into bipartite graphs and line graphs, and for which finding a maximum stable set is NP-hard. This shows that having holes all of the same parity gives essential properties for the use of 2-joins in computing stable sets. 相似文献