环面与Klein瓶上的5—流定理

本文证明了可嵌入环面与Klein瓶的图以及顶点数小于22的图存在处处非零5-流。     

嵌入在克莱茵瓶上的图的最大亏格

设$phi: Grightarrow S$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.     

Klein瓶上的奇异地图

It is well known that singular maps (i. e. ,those have only one face on a surface)play a key role in the theory of up-embeddability of graphs. In this paper the number of rooted singular maps on the Klein bottle is studied. An explicit form of the enumerating function according to the root-valency and the size of the map is determined. Further ,an expression of the vertex partition function is also found.     

关于图的子着色

本文主要讨论了子色唯一图的结构，并给出了唯一k-子色图、最大子色图的边临界子色图的特征．     

色数等于选择数的4-正则图

设Hn(n≥5)表示一个图:以1,2,．．．,n为顶点,两个点i和j是相邻的当且仅当|i-j|≤2,其中加法取模n．这篇文章证明了,Hn的色数等于它的选择数．结果被用于刻画最大度至多2的图的列表全色数．     

高度正则图的全着色

一个图$G$的全色数$\chi_T(G)$ 是对$G$的边和顶点着色的最小数, 使得相关联或相邻元素着不同色. 证明了如果$G$是正则图并且$d(G)\ge\cfrac{2}{3}|V(G)|+\cfrac{23}{6},$ 这里$d(G)$ 表示在$G$中顶点的度, 则$\chi_T(G)\leq d(G)+2$.     

互补图的星色数

本文给出互补图的星色数所满足的一些必要条件，并确定一些图类的星色数．     

联图的关联着色

图G的一个κ-关联着色是指从G的关联集I(G)到颜色集{1,2,…,κ}的一个映射,满足任意一对相邻的关联分配到不同的颜色.使得G有κ-关联着色的最小的数κ称为G的关联色数,记为X_i(G).研究了联图的关联着色,给出了G∨H的关联色数的一个上界,讨论了路与路,路与圈,圈与圈的联图的关联色数.     

克莱茵瓶上奇异地图的色数

A map is singular if each edge is on the same face on a surface (i.e., it has only one face on a surface). In this paper we present the chromatic enumeration for rooted singular maps on the Klein bottle.     

系列平行图SHMeredith图的关联着色

图的关联着色是从关联集到颜色集的一个映射,使得关联集中任何两个相邻的关联都具有不同的像.确定了Meredith图的关联色数,证明了对任意系列平行图都存在一个(Δ 2,2)-关联着色.     

Six-Critical Graphs on the Klein Bottle

We exhibit an explicit list of nine graphs such that a graph drawn in the Klein bottle is 5-colorable if and only if it has no subgraph isomorphic to a member of the list. This answers a question of Thomassen [J. Comb. Theory Ser. B 70 (1997), 67–100] and implies an earlier result of Král', Mohar, Nakamoto, Pangrác and Suzuki that an Eulerian triangulation of the Klein bottle is 5-colorable if and only if it has no complete subgraph on six vertices.     

Edge Partition of Graphs Embeddable in the Projective Plane and the Klein Bottle

In a previous paper by the author joint with Baogang XU published in Discrete Math in 2018, we show that every non-planar toroidal graph can be edge partitioned into a planar graph and an outerplanar graph. This edge partition then implies some results in thickness and outerthickness of toroidal graphs. In particular, if each planar graph has outerthickness at most $2$ (conjectured by Chartrand, Geller and Hedetniemi in 1971 and the confirmation of the conjecture was announced by Gon\c{c}alves in 2005), then the outerthickness of toroidal graphs is at most 3 which is the best possible due to $K_7$. In this paper we continue to study the edge partition for projective planar graphs and Klein bottle embeddable graphs. We show that (1) every non-planar but projective planar graph can be edge partitioned into a planar graph and a union of caterpillar trees; and (2) every non-planar Klein bottle embeddable graph can be edge partitioned into a planar graph and a subgraph of two vertex amalgamation of a caterpillar tree with a cycle with pendant edges. As consequences, the thinkness of projective planar graphs and Klein bottle embeddabe graphs are at most $2$, which are the best possible, and the outerthickness of these graphs are at most $3$.     

Drawing Disconnected Graphs on the Klein Bottle

We prove that two disjoint graphs must always be drawn separately on the Klein bottle in order to minimize the crossing number of the whole drawing.     

A6-invariant ovoids of the Klein quadric

Translation planes associated with A₆-invariant ovoids of the Klein quadric are discussed.     

Klein瓶上的双奇异地图

一个地图的每条边如果不是环就是割边(即该边的两边是同一个面的边界)，则称之为双奇异地图，本文研究Klein瓶上带根双奇异地图的计数问题，得到了此类地图以边数、平面环数、手柄上本质环数和又帽上本质环数为参数的计数公式，并得到了部分计数显式。     

The 2-Extendability of Graphs on the Projective Plane, the Torus and the Klein Bottle

A graph is said to be k-extendable if any independent set of k edges extends to a perfect matching. We shall show that every 5-connected graph of even order embedded on the projective plane and every 6-connected one embedded on the torus and the Klein bottle is 2-extendable and characterize the forbidden structures for 5-connected toroidal graphs to be 2-extendable.     

Coincidence Properties for Maps from the Torus to the Klein Bottle

The authors study the coincidence theory for pairs of maps from the Torus to the Klein bottle. Reidemeister classes and the Nielsen number are computed, and it is shown that any given pair of maps satisfies the Wecken property. The 1-parameter Wecken property is studied and a partial negative answer is derived. That is for all pairs of coincidence free maps a countable family of pairs of maps in the homotopy class is constructed such that no two members may be joined by a coincidence free homotopy.     

6—桥图的色唯一性

由连接两个顶点的S条内部不交的路组成的图叫S-桥图。本文讨论了6-桥图F（a,b,c,d,e,f)(a≤6≤c≤d≤e≤f)的色性,给出了此类图色唯一的一个充分条件;并证明6-桥图F(2,2,2,a,b)（a≥b≥3)是色唯一的。