The chromatic index of graphs with large maximum degree
نویسنده
چکیده
By Vizing’s theorem, the chromatic index x’(G) of a simple graph G satisfies d(G) Li 1 V(G)1 J + ir, where r is the number of vertices of maximum degree. A graph G is critical if G is Class 2 and x’(H) < x’(G) for all proper subgraphs H of G. We also describe the structure of critical graphs satisfying the inequality above. We also deduce, as a corollary, an earlier result of ours that a regular graph G of even order satisfying d(G) > $ ( V(G)( is Class 1. Ln 1990 Academic Press. Inc
منابع مشابه
Chromatic Harmonic Indices and Chromatic Harmonic Polynomials of Certain Graphs
In the main this paper introduces the concept of chromatic harmonic polynomials denoted, $H^chi(G,x)$ and chromatic harmonic indices denoted, $H^chi(G)$ of a graph $G$. The new concept is then applied to finding explicit formula for the minimum (maximum) chromatic harmonic polynomials and the minimum (maximum) chromatic harmonic index of certain graphs. It is also applied to split graphs and ce...
متن کاملThe distinguishing chromatic number of bipartite graphs of girth at least six
The distinguishing number $D(G)$ of a graph $G$ is the least integer $d$ such that $G$ has a vertex labeling with $d$ labels that is preserved only by a trivial automorphism. The distinguishing chromatic number $chi_{D}(G)$ of $G$ is defined similarly, where, in addition, $f$ is assumed to be a proper labeling. We prove that if $G$ is a bipartite graph of girth at least six with the maximum ...
متن کاملThe Distance-t Chromatic Index of Graphs
We consider two graph colouring problems in which edges at distance at most t are given distinct colours, for some fixed positive integer t. We obtain two upper bounds for the distance-t chromatic index, the least number of colours necessary for such a colouring. One is a bound of (2− ε)∆t for graphs of maximum degree at most ∆, where ε is some absolute positive constant independent of t. The o...
متن کاملA new approach to compute acyclic chromatic index of certain chemical structures
An acyclic edge coloring of a graph is a proper edge coloring such that there are no bichromatic cycles. The acyclic chromatic index of a graph $G$ denoted by $chi_a '(G)$ is the minimum number $k$ such that there is an acyclic edge coloring using $k$ colors. The maximum degree in $G$ denoted by $Delta(G)$, is the lower bound for $chi_a '(G)$. $P$-cuts introduced in this paper acts as a powerfu...
متن کاملOn the chromatic index of almost all graphs
Vizing has shown that if G is a simple graph with maximum vertex-degree p, then the chromatic index of G is either p or p + 1 . In this note we prove that almost all graphs have a unique vertex of maximum degree, and we deduce that almost all graphs have chromatic index equal to their maximum degree . This settles a conjecture of the second author (in "Proceedings of the Fifth British Combinato...
متن کاملINSTITUTO DE COMPUTAÇ O UNIVERSIDADE ESTADUAL DE CAMPINAS Edge-Coloring of Split Graphs
The Classification Problem is the problem of deciding whether a simple graph has chromatic index equals to ∆ or ∆+1, where ∆ is the maximum degree of the graph. It is known that to decide if a graph has chromatic index equals to ∆ is NP-complete. A split graph is a graph whose vertex set admits a partition into a stable set and a clique. The chromatic indexes for some subsets of split graphs, s...
متن کاملذخیره در منابع من
با ذخیره ی این منبع در منابع من، دسترسی به آن را برای استفاده های بعدی آسان تر کنید
عنوان ژورنال:
- J. Comb. Theory, Ser. B
دوره 48 شماره
صفحات -
تاریخ انتشار 1983