Hajós' conjecture for line graphs

نویسنده

  • Carsten Thomassen
چکیده

We prove that, if a graph G (without multiple edges) has maximum degree d and edge-chromatic number d + 1, then G contains two distinct vertices x, y and a collection of d pairwise edge-disjoint paths between x and y. In particular, the line graph of G satisfies Hajós’ conjecture. © 2006 Elsevier Inc. All rights reserved.

برای دانلود متن کامل این مقاله و بیش از 32 میلیون مقاله دیگر ابتدا ثبت نام کنید

ثبت نام

اگر عضو سایت هستید لطفا وارد حساب کاربری خود شوید

منابع مشابه

Hadwiger's Conjecture for the Complements of Kneser Graphs

A graph H is a minor of a graph G if a graph isomorphic to H can be obtained from a subgraph of G by contracting edges. An H-minor is a minor isomorphic to H. The Hadwiger number of G, denoted by h(G), is the maximum integer t such that G contains a Kt-minor, where Kt is the complete graph with t vertices. Hadwiger [8] conjectured that every graph that is not (t−1)-colourable contains a Kt-mino...

متن کامل

Triangulations and the Hajós Conjecture

The Hajós Conjecture was disproved in 1979 by Catlin. Recently, Thomassen showed that there are many ways that Hajós conjecture can go wrong. On the other hand, he observed that locally planar graphs and triangulations of the projective plane and the torus satisfy Hajós Conjecture, and he conjectured that the same holds for arbitrary triangulations of closed surfaces. In this note we disprove t...

متن کامل

On a Coloring Conjecture of Hajós

Hajós conjectured that graphs containing no subdivision of K5 are 4-colorable. It is shown in [15] that if there is a counterexample to this conjecture then any minimum such counterexample must be 4-connected. In this paper, we further show that if G is a minimum counterexample to Hajós’ conjecture and S is a 4-cut in G then G− S has exactly two components. AMS Subject Classification: 05C15, 05...

متن کامل

-λ coloring of graphs and Conjecture Δ ^ 2

For a given graph G, the square of G, denoted by G2, is a graph with the vertex set V(G) such that two vertices are adjacent if and only if the distance of these vertices in G is at most two. A graph G is called squared if there exists some graph H such that G= H2. A function f:V(G) {0,1,2…, k} is called a coloring of G if for every pair of vertices x,yV(G) with d(x,y)=1 we have |f(x)-f(y)|2 an...

متن کامل

On Gallai's and Hajós' Conjectures for graphs with treewidth at most 3

A path (resp. cycle) decomposition of a graph G is a set of edge-disjoint paths (resp. cycles) of G that covers the edge set of G. Gallai (1966) conjectured that every graph on n vertices admits a path decomposition of size at most ⌊(n+ 1)/2⌋, and Hajós (1968) conjectured that every Eulerian graph on n vertices admits a cycle decomposition of size at most ⌊(n−1)/2⌋. Gallai’s Conjecture was veri...

متن کامل

ذخیره در منابع من


  با ذخیره ی این منبع در منابع من، دسترسی به آن را برای استفاده های بعدی آسان تر کنید

برای دانلود متن کامل این مقاله و بیش از 32 میلیون مقاله دیگر ابتدا ثبت نام کنید

ثبت نام

اگر عضو سایت هستید لطفا وارد حساب کاربری خود شوید

عنوان ژورنال:
  • J. Comb. Theory, Ser. B

دوره 97  شماره 

صفحات  -

تاریخ انتشار 2007