共查询到20条相似文献,搜索用时 140 毫秒
1.
图的L(d,1,1)-标号定义为顶点集V(G)到非负整数集的映射f,且当d(u,v)=1时,均有|f(u)-f(v)|≥d,当d(u,v)=2,3时,均有|f(u)-f(v)|≥1.不妨设0为最小标号,则称图G的所有L(d,1,1)-标号中的最大跨度max{f(v):v∈V(G)}的最小数为图的L(d,1,1)-标号数,记为λd(G).基本给出了竖梯的局部替换图的L(d,1,1)-标号数的确切值或界. 相似文献
2.
An L(2,1)-labeling of a graph G is a function f from the vertex set V(G) to the set of all nonnegative integers such that |f(x)-f(y)|(?)2 if d(x, y)=1 and |f(x)-f(y)|(?)1 if d(x,y)=2. The L(2,1)-labeling numberλ(G) of G is the smallest number k such that G has an L(2,1)-labeling with max{f(v) : v∈V(G)}=k. We study the L(3,2,1)-labeling which is a generalization of the L(2,1)-labeling on the graph formed by the (Cartesian) product and composition of 3 graphs and derive the upper bounds ofλs(G) of the graph. 相似文献
3.
The induced matching cover number of a graph G without isolated vertices,denoted by imc(G),is the minimum integer k such that G has k induced matchings M1,M2,…,Mk such that,M1∪M2 ∪…∪Mk covers V(G).This paper shows if G is a nontrivial tree,then imc(G) ∈ {△*0(G),△*0(G) + 1,△*0(G)+2},where △*0(G) = max{d0(u) + d0(v) :u,v ∈ V(G),uv ∈ E(G)}. 相似文献
4.
设G是一个图.G的顶点u和v的距离是u和v之间最短路的长度.Wiener指数是G中所有无序顶点对之间距离之和,而Hyper-Wiener指数定义为WW(G)=?∑u,v∈V(G)d(u,v)+?∑u,v∈V(G)d2(u,v),式中的和取遍G的所有顶点对.本文总结了图的Hyper-Wiener指数的最近结论. 相似文献
5.
6.
An L(2,1)-labelling of a graph G is a function from the vertex set V (G) to the set of all nonnegative integers such that |f(u) f(v)| ≥ 2 if d G (u,v)=1 and |f(u) f(v)| ≥ 1 if d G (u,v)=2.The L(2,1)-labelling problem is to find the smallest number,denoted by λ(G),such that there exists an L(2,1)-labelling function with no label greater than it.In this paper,we study this problem for trees.Our results improve the result of Wang [The L(2,1)-labelling of trees,Discrete Appl.Math.154 (2006) 598-603]. 相似文献
7.
8.
9.
本文研究关于余直径的度条件,主要结果是,若G是3-连通图,其顶点集为V(G)={v1,v2,…,vn),其度序列为: d(v1)≤d(v2)≤…≤d(vn)则对G的任意一条边e都存在特征点对va,vb,使G中过e的最长圈至少为d(va)+d(vb)-1.在相同的条件下我们有d*(G)≥ m-2, 相似文献
10.
An f-coloring of a graph G is an edge-coloring of G such that each color appears at each vertex v∈V(G) at most f(v) times.The f-core of G is the subgraph of G induced by the vertices v of degree d(v)=f(v) maxv∈V(G){ d(v)/f(v) }.In this paper,we find some necessary conditions for a simple graph,whose f-core has maximum degree two,to be of class 2 for f-colorings. 相似文献
11.
图G的零阶广义Randi指标定义为0Rα(G)=v∈V(G)d(v)α,其中d(v)为图G的顶点v的度,α为任意实数.研究了树的零阶广义Rα指标的极值问题,利用分析和图的理论,确定了任意给定最大匹配数的树的最大和最小Rα的值,并刻画了达到该极值的树. 相似文献
12.
对一个连通图G,令d(u,v)表示G中两个顶点间u和v之间的距离,d表示G的直径.G的一个对极染色指的是从G的顶点集到正整数集(颜色集)的一个映射c,使得对G的任意两个不同的顶点u和v满足d(u,v)+|c(u)-c(v)|≥d.由c映射到G的顶点的最大颜色称为c的值,记作ac(c),而对G的所有对极染色c,ac(c)的最小值称为G的对极色数,记作ac(G).本文确定了轮图、齿轮图以及双星图三类图的对极色数,这些图都具有较小的直径d. 相似文献
13.
14.
Acta Mathematicae Applicatae Sinica, English Series - A fractional [a, b]-factor of a graph G is a function h from E(G) to [0, 1] satisfying $$a \le d_G^h(v) \le b$$ for every vertex v of G, where... 相似文献
15.
16.
刘克强 《数学的实践与认识》2020,(5):99-103
图G的调和指标是指图G中所有边uv所对应的2/d(u)+d(v)权和,其中d(u),d(v)分别表示顶点u,v的度数.本文的主要目标是计算出所有的n个顶点的two-tree图中的最小与第二小的调和指标. 相似文献
17.
图G的一个L(2.1)-标号是从顶点集V(G)到非负整数的一个函数f,使得若d(u,v)=1时,有|f(u)-f(v)|≥2;若d(u,v)=2时,有|f(u)-f(v)|≥1.图G的L(2.1)-标号数λ(G)是G的所有L(2.1)-标号下的跨度max{f(v):v∈V(G)}的最小数.图Fn+1*为扇图的路上每个顶点增加一个悬挂边得到的图.图Hn为轮图的圈上每个顶点增加一个悬挂边得到的图.本文确定了图Fn+1*与Hn的L(2.1)-标号数. 相似文献
18.
Let G be a simple graph.An IE-total coloring f of G refers to a coloring of the vertices and edges of G so that no two adjacent vertices receive the same color.Let C(u) be the set of colors of vertex u and edges incident to u under f.For an IE-total coloring f of G using k colors,if C(u)=C(v) for any two different vertices u and v of V(G),then f is called a k-vertex-distinguishing IE-total-coloring of G,or a k-VDIET coloring of G for short.The minimum number of colors required for a VDIET coloring of G is denoted by χ ie vt (G),and it is called the VDIET chromatic number of G.We will give VDIET chromatic numbers for complete bipartite graph K4,n (n≥4),K n,n (5≤ n ≤ 21) in this article. 相似文献
19.