## Abstract Gol'dberg has recently constructed an infinite family of 3βcritical graphs of even order. We now prove that if there exists a __p__(β₯4)βcritical graph __K__ of odd order such that __K__ has a vertex __u__ of valency 2 and another vertex __v__ β __u__ of valency β€(__p__ + 2)/2, then ther
Remarks on the critical graph conjecture
β Scribed by I. Broere; C.M. Mynhardt
- Publisher
- Elsevier Science
- Year
- 1979
- Tongue
- English
- Weight
- 344 KB
- Volume
- 26
- Category
- Article
- ISSN
- 0012-365X
No coin nor oath required. For personal study only.
β¦ Synopsis
The vertex-critical graph conjecture (critical graph conjecture respectively) states that every vertex-critical (critical) graph has an odd number of vertices. In this note we prove that if G is a critical graph of even order, then G has at least three vertices of less-than-maximum valency. In addition, if G is a 3-critical multigraph of smallest even order, then G is simple and has no triangles.
π SIMILAR VOLUMES
## Abstract In this expository paper we discuss the critical graph conjecture and its eventual disproof by M.K. Goldberg and others.
Let F be a connected graph. F is said to be interval-regular if I F~\_ l(u) uF(x )J =. i holds for all vertices u and x ~ Fi(u), i > 0. For u, v e F, let I (u, v) denote the set of all vertices on a shortest path connecting u, v. A subset W of V(F) is said to be convex if l(u,v) c W holds for each u
A graph G is perfect if for every induced subgraph H of G the chromatic number x(H) equals the largest number w ( H ) of pairwise adjacent vertices in H. Berge's famous Strong Perfect Graph Conjecture asserts that a graph G is perfect if and only if neither G nor its complement C contains an odd cho
Let K~ ) be the umon of two complete graphs on n vertices which have preosely one vertex in common. Graham and Sloane have shown that K~ ~ is not harmomous for n od:~, /(~,~ is harmonious, and K~62~ is not harmonious. They also conjecture that K~' t,, not h,~rmomous except for n = 4. Here, it Is sho