## Abstract We give examples of edge‐chromatic critical graphs __G__ of the following types: (i) of even order and having no 1‐factor, and (ii) of odd order and having a vertex __v__ of minimum degree such that __G__ − __v__ has no 1‐factor. The first disproves a conjecture of S. Fiorini and R. J.
Independent sets and 2-factors in edge-chromatic-critical graphs
✍ Scribed by Stefan Grünewald; Eckhard Steffen
- Publisher
- John Wiley and Sons
- Year
- 2003
- Tongue
- English
- Weight
- 66 KB
- Volume
- 45
- Category
- Article
- ISSN
- 0364-9024
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✦ Synopsis
Abstract
In 1968, Vizing made the following two conjectures for graphs which are critical with respect to the chromatic index: (1) every critical graph has a 2‐factor, and (2) every independent vertex set in a critical graph contains at most half of the vertices. We prove both conjectures for critical graphs with many edges, and determine upper bounds for the size of independent vertex sets in those graphs. © 2003 Wiley Periodicals, Inc. J Graph Theory 45: 113–118, 2004
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