A k-critical (multi-) graph G has maximum degree k, chromatic index Ο (G) = k + 1, and Ο (G -e) < k + 1 for each edge e of G. For each k β₯ 3, we construct k-critical (multi-) graphs with certain properties to obtain counterexamples to some well-known conjectures.
The chromatic index of graphs of even order with many edges
β Scribed by A. G. Chetwynd; A. J. W. Hilton
- Publisher
- John Wiley and Sons
- Year
- 1984
- Tongue
- English
- Weight
- 313 KB
- Volume
- 8
- Category
- Article
- ISSN
- 0364-9024
No coin nor oath required. For personal study only.
β¦ Synopsis
We show that, for r = 1, 2, a graph G with 2n + 2 (26) vertices and maximum degree 2n + 1 -r is of Class 2 if and only if (E(G\v)I > ('"2+')m, where v is a vertex of G of minimum degree, and we make a conjecture for 1 s r s n, of which this result is a special case. For r = 1 this result is due to Plantholt.
π SIMILAR VOLUMES
A chromatic-index-critical graph G on n vertices is non-trivial if it has at most n 2 edges. We prove that there is no chromatic-index-critical graph of order 12, and that there are precisely two non-trivial chromatic-index-critical graphs on 11 vertices. Together with known results this implies tha
## Abstract Vizing's Theorem states that any graph __G__ has chromatic index either the maximum degree Ξ(__G__) or Ξ(__G__) + 1. If __G__ has 2~s~ + 1 points and Ξ(__G__) = 2s, a wellβknown necessary condition for the chromatic index to equal 2~s~ is that __G__ have at most 2s^2^ lines. Hilton conj
## Abstract We show that a complete multipartite graph is class one if and only if it is not eoverfull, thus determining its chromatic index.
In this paper, by applying the discharging method, we prove that if
## Abstract In 1968, Vizing [Uaspekhi Mat Nauk 23 (1968) 117β134; Russian Math Surveys 23 (1968), 125β142] conjectured that for any edge chromatic critical graph ${{G}} = ({{V}}, {{E}})$ with maximum degree $\Delta$, $|{{E}}| \geq {{{1}}\over {{2}}}\{(\Delta {{- 1}})|{{V}}| + {{3}}\}$. This conject