关于乘积图的二维带宽问题

给出一般乘积图的二维带宽的界，并解决一类乘积图的二维带宽问题．最后给出完全ｋ部图的二维带宽。     

二维带宽的浓度下界

二维带宽问题是确定图Ｇ在平面格子图中的一个嵌入，使最长的边尽可能短，本文研究若干个下界以及它们应用于带宽的估值。所有结果均建立在一种平面组合几何的方法之上，其中的浓度下界改进了文献（３）的结果。     

关于L∞—模距离的二维带宽问题

二维宽带问题是将图G嵌入平面格子图,使其最长的连边尽可能短,迄今为止,在平面格子图中考虑的距离为矩线距离,即L1－模距离,在本文中,我们研究在L∞－模距离意义下的二维带宽问题。     

二维带宽的浓度下界（英）

二维带宽问题是确定图G在平面格子图中的一个嵌入，使最长的边尽可能短.本文研究若干个下界以及它们应用于带宽的估值.所有结果均建立在一种平面组合几何的方法之上.其中的浓度下界改进了文献[3]的结果.     

单节点图的弱最大亏格

单节点图即只有一个点的图.本文讨论了该图类的三种嵌入.并得到了对应的最大亏格.对于这类图的弱嵌入.插值定理是成立的.     

关于点的度在modulo下等值的上可嵌入图类

结合４－边形２－因子条件,确定了一类点的度在ｍｏｄｕｌｏ４下值为０,１的上可嵌入图类,从而综合已有的结果,较完整地刻划了这类图的上可嵌入性情况。     

一类循环图在射影平面上的嵌入北大核心CSCD

嵌入的联树模型是研究图的曲面嵌入的一种有效方法,尤其能方便快捷地研究图在球面,环面,射影平面,Klein瓶上的嵌入。此方法通过合理选择生成树,得到联树和关联曲面,然后对关联曲面进行计数,计算出图在曲面上的嵌入个数.本文利用嵌入的联树模型得出了循环图C(2n+1,2)(n>2)在射影平面上的嵌入个数.     

二次图构形的边搜索法及其Orlik-Solomon代数的上同调

本文研究了一类特殊的图构形,即二次图构形.首先,给出了弦图的边搜索法,用边搜索法可以决定弦图所对应的超平面构形中超平面的哪些排序使构形是二次均.其次,对二次图构形的Orlik-Solomon代数作为线性空间的维数进行了计算,得到了它的Poincare多项式的表达式.最后,对二次图构形Orlik-Solomon代数的上同调进行了研究,对边缘算子集中在秩为二的模元时,得到了二次图构形的Orlik-Solomon代数的上同调的维数计算公式.     

图的最大亏格的一个性质

本文所考虑的图均指有限元向图，没有解释的术语和记号同[1]．一个图称为简单图如果不含重边及环．曲面S这里指一个紧的，连通的，2－维闭流形（定向或不可定向），其亏格记为g（S）．连通图G在曲面S上的一个2－胞腔嵌入意指存在一个1－1连续映射h：G→S使得S＼h（G）的每个连通分支与圆盘拓扑同胚．连通图G的定向亏格γ（G）（或不可定向亏格γ（G））是指最小的整数k使得G在亏格为k的定向（或不可走向）曲面S上有2－胞腔嵌入；而图G的最大定向亏格，也常称之为最大亏格，记为γM（G）,是指最大的整数k使得G在亏格为k定向曲面S上有…     

图的上可嵌入性与圈中顶点度

本文利用非上可嵌入图的充要条件,结合圈中顶点最大度与图的上可嵌入性之间的关系,得到了下两个结果:(1)设G是2-边连通简单图,若对G中任意圈G,存在点x∈C满足,d(x)>|V(G)|/3 1,则图G是上可嵌入的,且不等式的下界是不可达的.(2)设G={x,y;E}为简单二都图,且是2-边连通的. |x|=m,|Y|=n(m,n≥3),若对G中任意圈C,存在点x∈C且x∈X满足d(x)>n/3 1,则图G是上可嵌入的,且不等式的下界是不可达的.     

Cycle embedding in star graphs with conditional edge faults

Among the various interconnection networks, the star graph has been an attractive one. In this paper, we consider the cycle embedding problem in star graphs with conditional edge faults. We show that there exist cycles of all even lengths from 6 to n! in an n-dimensional star graph with ?2n-7 edge faults in which each vertex is incident with at least two healthy edges for n?4.     

A circular embedding of a graph in Euclidean 3-space

A spatial embedding of a graph G is an embedding of G into the 3-dimensional Euclidean space . J.H. Conway and C.McA. Gordon proved that every spatial embedding of the complete graph on 7 vertices contains a nontrivial knot. A linear spatial embedding of a graph is an embedding which maps each edge to a single straight line segment. In this paper, we construct a linear spatial embedding of the complete graph on 2n−1 (or 2n) vertices which contains the torus knot T(2n−5,2) (n4). A circular spatial embedding of a graph is an embedding which maps each edge to a round arc. We define the circular number of a knot as the minimal number of round arcs in among such embeddings of the knot. We show that a knot has circular number 3 if and only if the knot is a trefoil knot, and the figure-eight knot has circular number 4.     

Closed 2-cell embeddings of graphs with no V8-minors

A closed 2-cell embedding of a graph embedded in some surface is an embedding such that each face is bounded by a cycle in the graph. The strong embedding conjecture says that every 2-connected graph has a closed 2-cell embedding in some surface. In this paper, we prove that any 2-connected graph without V₈ (the Möbius 4-ladder) as a minor has a closed 2-cell embedding in some surface. As a corollary, such a graph has a cycle double cover. The proof uses a classification of internally-4-connected graphs with no V₈-minor (due to Kelmans and independently Robertson), and the proof depends heavily on such a characterization.     

嵌入在克莱茵瓶上的图的最大亏格

设$\phi: G\rightarrow S$是图$G$在曲面$S$上的2 -胞腔嵌入. 若$G$的所有面都是依次相邻, 即嵌入图$G$的对偶图有哈密顿圈, 则将$\phi$称为一个面依次相邻的嵌入. 该文研究了在克莱茵瓶上有面依次相邻嵌入的图的最大亏格.     

Maximum Genus of Strong Embeddings

The strong embedding conjecture states that any 2-connected graph has a strong embedding on some surface. It implies the circuit double cover conjecture: Any 2-connected graph has a circuit double cover.Conversely, it is not true. But for a 3-regular graph, the two conjectures are equivalent. In this paper, a characterization of graphs having a strong embedding with exactly 3 faces, which is the strong embedding of maximum genus, is given. In addition, some graphs with the property are provided. More generally, an upper bound of the maximum genus of strong embeddings of a graph is presented too. Lastly, it is shown that the interpolation theorem is true to planar Halin graph.     

Matrices and graphs of essential dependence of proper families of functions

This paper considers proper families of functions, which are used in functional specification of Latin squares of large size over the set of n-dimensional binary vectors. Proper families of functions are studied from the viewpoint of the intrinsic structure of the corresponding graphs of essential dependence and their adjacency matrices. Various necessary and sufficient conditions for a binary matrix to be treated as the adjacency matrix of the graph of essential dependence of a proper family of functions are derived. Also, transformations of matrices are considered under which the indicated property is preserved. It is demonstrated that any directed graph without loops and multiple edges can be embedded as an induced subgraph into the graph of essential dependence of some proper family of functions. Moreover, such embedding is reasonably economical, and the functions of the resulting proper family inherit properties of the functions that realize the original graph as the graph of essential dependence.     

A relative maximum genus graph embedding and its local maximum genus

A relative embedding of a connected graph is an embedding of the graph in some surface with respect to some closed walks, each of which bounds a face of the embedding. The relative maximum genus of a connected graph is the maximum of integerk with the property that the graph has a relative embedding in the orientable surface withk handles. A polynomial algorithm is provided for constructing relative maximum genus embedding of a graph if the relative tree of the graph is planar. Under this condition, just like maximum genus embedding, a graph does not have any locally strict maximum genus.     

Memetic algorithm for the antibandwidth maximization problem

The antibandwidth maximization problem (AMP) consists of labeling the vertices of a n-vertex graph G with distinct integers from 1 to n such that the minimum difference of labels of adjacent vertices is maximized. This problem can be formulated as a dual problem to the well known bandwidth problem. Exact results have been proved for some standard graphs like paths, cycles, 2 and 3-dimensional meshes, tori, some special trees etc., however, no algorithm has been proposed for the general graphs. In this paper, we propose a memetic algorithm for the antibandwidth maximization problem, wherein we explore various breadth first search generated level structures of a graph—an imperative feature of our algorithm. We design a new heuristic which exploits these level structures to label the vertices of the graph. The algorithm is able to achieve the exact antibandwidth for the standard graphs as mentioned. Moreover, we conjecture the antibandwidth of some 3-dimensional meshes and complement of power graphs, supported by our experimental results.     

Cycle embedding in star graphs with more conditional faulty edges

The star graph is one of the most attractive interconnection networks. The cycle embedding problem is widely discussed in many networks, and edge fault tolerance is an important issue for networks since edge failures may occur when a network is put into use. In this paper, we investigate the cycle embedding problem in star graphs with conditional faulty edges. We show that there exist fault-free cycles of all even lengths from 6 to n! in any n-dimensional star graph S_n (n ? 4) with ?3n − 10 faulty edges in which each node is incident with at least two fault-free edges. Our result not only improves the previously best known result where the number of tolerable faulty edges is up to 2n − 7, but also extends the result that there exists a fault-free Hamiltonian cycle under the same condition.