图G为自构线图的充要条件

首次给出自构线图的定义,并证明:简单图G为自构线图的充要条件是图G为2-正则简单图.     

The Spectrum and Automorphism Group of the Set-Inclusion Graph

Let n,k and l be integers with 1 ≤ k ＜ l ≤ n-1.The set-inclusion graph G(n,k,l) is the graph whose vertex set consists of all k-andl-subsets of[n]={1,2,...,n},where two distinct vertices are adjacent if one of them is contained in the other.In this paper,we determine the spectrum and automorphism group of G(n,k,l).     

The Semi-Arc Automorphism Group of a Graph with Application to Map Enumeration

A map is a connected topological graph cellularly embedded in a surface. For a given graph Γ, its genus distribution of rooted maps and embeddings on orientable and non-orientable surfaces are separately investigated by many researchers. By introducing the concept of a semi-arc automorphism group of a graph and classifying all its embeddings under the action of its semi-arc automorphism group, we find the relations between its genus distribution of rooted maps and genus distribution of embeddings on orientable and non-orientable surfaces, and give some new formulas for the number of rooted maps on a given orientable surface with underlying graph a bouquet of cycles B_n, a closed-end ladder L_n or a Ringel ladder R_n. A general scheme for enumerating unrooted maps on surfaces(orientable or non-orientable) with a given underlying graph is established. Using this scheme, we obtained the closed formulas for the numbers of non-isomorphic maps on orientable or non-orientable surfaces with an underlying bouquet B_n in this paper.     

An Ergodic Action of the Outer Automorphism Group of a Free Group

For n > 2, the action of the outer automorphism group of the rank n free group F _n on Hom(F _n , SU(2))/SU(2) is ergodic with respect to the Lebesgue measure class. The author gratefully acknowledges support from National Science Foundation grants DMS-0405605 and DMS-0103889. Received: September 2005 Revision: January 2006 Accepted: March 2006     

On the Stabilizer of the Automorphism Group of a 4—valent Vertex—transitive Graph with Odd—prime—power Order

Let X be a 4-valent connected vertex-transitive graph with odd-prime-power order p^κ（κ≥1） and let A be the full automorphism group of X.In this paper,we prove that the stabilizer Av of a vertex v in A is a 2-group if p≠5,or a {2,3}-group if p=5.Furthermore,if p=5|Av| is not divisible by 3^2.As a result ,we show that any 4-valent connected vertex-transitive graph with odd-prime-power order p^κ(κ≥1） is at most 1-arc-transitive for p≠5 and 2-arc-transitive for p=5.     

Integer Functions on the Cycle Space and Edges of a Graph

A directed graph has a natural \mathbb Z{\mathbb {Z}} -module homomorphism from the underlying graph’s cycle space to \mathbb Z{\mathbb {Z}} where the image of an oriented cycle is the number of forward edges minus the number of backward edges. Such a homomorphism preserves the parity of the length of a cycle and the image of a cycle is bounded by the length of that cycle. Pretzel and Youngs (SIAM J. Discrete Math. 3(4):544–553, 1990) showed that any \mathbb Z{\mathbb {Z}} -module homomorphism of a graph’s cycle space to \mathbb Z{\mathbb {Z}} that satisfies these two properties for all cycles must be such a map induced from an edge direction on the graph. In this paper we will prove a generalization of this theorem and an analogue as well.     

Determination of a Domain in Complex Space by its Automorphism Group

We consider results, both in one complex variable and several, which show that the algebraic or geometric structure of the automorphism group of a domain z can determine that domain. The domains considered include Ω = B, the unit ball in C ⁿ , and Ω = C ⁿ . Various illustrative examples are provided.     

Long Cycles Generate the Cycle Space of a Graph

Let G be a 2-connected graph in which the degree of every vertex is at least d. We prove that the cycles of length at least d + 1 generate the cycle space of G, unless G ≌ K_d+1 and d is odd. As a corollary, we deduce that the cycles of length at least d + 1 generate the subspace of even cycles in G. We also establish the existence of odd cycles of length at least d + 1 in the case when G is not bipartite.A second result states: if G is 2-connected with chromatic number at least k, then the cycles of length at least k generate the cycle space of G, unless G ≌ K_k and k is even. Similar corollaries follow, among them a stronger version of a theorem of Erdös and Hajnal.     

The Automorphism Group and the Convex Subgraphs of the Quadratic Forms Graph in Characteristic 2

We determine the automorphism group and the convex subgraphs of the quadratic forms graph Quad(n,q),q even.A. Munemasa: A part of this research was completed during this author's visit at the Institute for System Analysis, Moscow, as a Heizaemon Honda fellow of the Japan Association for Mathematical SciencesD.V. Pasechnik: A part of this research was completed when this author held a position at the Institute for System Analysis, MoscowS.V. Shpectorov: A part of this research was completed during this author's visit at the University of Technology, Eindhoven     

Correction to the Paper - Determination of a Domain in Complex Space by its Automorphism Group

The author offers some corrections to his article which appeared in Vol. 47, No. 3 of this journal.     

非拟本原（PSU3（P），2）-弧传递图的外自同构

证明由GF（p^2）的域自同构可以产生一类非拟本原（PSU3（P）,2）-弧传递图的白同构,并研究了这样的自同构与图的传递自同构群中心化予的关系。     

Adjoint Action of Automorphism Groups on Radical Endomorphisms,Generic Equivalence and Dynkin Quivers

Let Q be a connected quiver with no oriented cycles, k the field of complex numbers and P a projective representation of Q. We study the adjoint action of the automorphism group Aut _kQ P on the space of radical endomorphisms radEnd _kQ P. Using generic equivalence, we show that the quiver Q has the property that there exists a dense open Aut _kQ P-orbit in radEnd _kQ P, for all projective representations P, if and only if Q is a Dynkin quiver. This gives a new characterisation of Dynkin quivers.     

Viscous Flows in a Half Space Caused by Tangential Vibrations on Its Boundary

The paper is devoted to the studies of viscous flows caused by a vibrating boundary. The fluid domain is a half‐space, its boundary is a nondeformable plane that exhibits purely tangential vibrations. Such a simple geometrical setting allows us to study general boundary velocity fields and to obtain general results. From a practical viewpoint, such boundary conditions may be seen as the tangential vibrations of the material points of a stretchable plane membrane. In contrast to the classical boundary layer theory, we aim to build a global solution. To achieve this goal we employ the Vishik–Lyusternik approach, combined with two‐timing and averaging methods. Our main result is: we obtain a uniformly valid in the whole fluid domain approximation to the global solutions. This solution corresponds to general boundary conditions and to three different settings of the main small parameter. Our solution always include the inner part and outer part that both contain oscillating and non‐oscillating components. It is shown that the nonoscillating outer part of the solution is governed either by the full Navier–Stokes equations or the Stokes equations (both with the unit viscosity) and can be interpreted as a steady or unsteady streaming. In contrast to the existing theories of a steady streaming, our solutions do not contain any secular (infinitely growing with the inner normal coordinate) terms. The examples of the spatially periodic vibrations of the boundary and the angular torsional vibrations of an infinite rigid disc are considered. These examples are still brief and illustrative, while the core of the paper is devoted to the adaptation of the Vishik–Lyusternik method to the development of the general theory of vibrational boundary layers.     

On the Cycle Space of an Infinite 3-connected Graph

Problems related to Tutte’s theorem on the generation of the cycle space of a 3-connected finite graph are discussed for infinite graphs.     

图的倍图与补倍图

计算机科学数据库的关系中遇到了可归为倍图或补倍图的参数和哈密顿圈的问题．对简单图C,如果V（D（G））：V（G）∪V（G′）E（D（G））=E（C）∪E（C″）U{vivj′｜vi∈V（G）,Vj′∈V（G′）且vivj∈E（G））那么,称D（C）是C的倍图,如果V（D（G））=V（C）∪V（G′）,E（D（C））：E（C）∪E（G′）∪{vivj′}vi∈V（G）,vj′∈V（G’）and vivj∈（G））,称D（C）是G的补倍图,这里G′是G的拷贝．本文研究了D（G）和D的色数,边色数,欧拉性,哈密顿性和提出了D（G） 的边色数是D（G）的最大度等公开问题．     

Structure of a Conjugating Automorphism Group

We examine the automorphism group Aut(F _n ) of a free group F _n of rank n 2 on free generators x ₁, x ₂,...,x _n . It is known that Aut(F ₂) can be built from cyclic subgroups using a free and semidirect product. A question remains open as to whether this result can be extended to the case n > 2. Every automorphism of Aut(F _n ) sending a generator x _i to an element f _i ^-1 x _(i) f _i , where f _i F _n and is some permutation on a symmetric group S _n , is called a conjugating automorphism. The conjugating automorphism group is denoted C _n . A set of automorphisms for which is the identity permutation form a basis-conjugating automorphism group, denoted Cb _n . It is proved that Cb _n can be factored into a semidirect product of some groups. As a consequence we obtain a normal form for words in C _n . For n 4, C _n and Cb _n have an undecidable occurrence problem in finitely generated subgroups. It is also shown that C _n , n 2, is generated by at most four elements, and we find its respective genetic code, and that Cb _n , n 2, has no proper verbal subgroups of finite width.     

On the Maximum Matching Graph of a Graph

1IntroductionMatchingtheory,aswellastheassignmentprobleminlinearprogramming,hasawiderangeofapplicationinthetheoryandpracticeofoperationsresearch.Bysomepracticalmotivations,e.g.,forfindingalloptimalsolutions,peoplewanttoknowthestructurepropertiesofallmaximummatchingsofagraphG.InthecasethatGhasperfectmatchings,extensiveworkhasbeendoneontheso-calledperfectmatChinggrape(or1-factorgraph),inwhichtwoperfectmatchingsMIandMZaresaidtobeadjacentifMI~MZ@E(C)whereCisanMI-alternatingcycleofG.Therewer…