## Abstract P. Erdős conjectured in [2] that __r__‐regular 4‐critical graphs exist for every __r__ ≥ 3 and noted that no such graphs are known for __r__ ≥ 6. This article contains the first example of a 6‐regular 4‐critical graph. © 2002 Wiley Periodicals, Inc. J Graph Theory 41: 286–291, 2002
Regular 4-critical graphs of even degree
✍ Scribed by Andrey A. Dobrynin; Leonid S. Melnikov; Artem V. Pyatkin
- Publisher
- John Wiley and Sons
- Year
- 2004
- Tongue
- English
- Weight
- 237 KB
- Volume
- 46
- Category
- Article
- ISSN
- 0364-9024
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✦ Synopsis
Abstract
In 1960, Dirac posed the conjecture that r‐connected 4‐critical graphs exist for every r ≥ 3. In 1989, Erdős conjectured that for every r ≥ 3 there exist r‐regular 4‐critical graphs. In this paper, a technique of constructing r‐regular r‐connected vertex‐transitive 4‐critical graphs for even r ≥ 4 is presented. Such graphs are found for r = 6, 8, 10. © 2004 Wiley Periodicals, Inc. J Graph Theory 46: 103–130, 2004
📜 SIMILAR VOLUMES
A p-factor of a graph G is a regular spanning subgraph of degree p . For G regular of degree d ( G ) and order 2n, let ( p l , ..., p,) be a partition of d ( G ) , so that p i > 0 ( I S i S r ) and p , i i pr = d(G). If H I . ..., H, are edge-disjoint regular spanning subgraphs of G of degrees p I ,
A k-critical (multi-) graph G has maximum degree k, chromatic index χ (G) = k + 1, and χ (G -e) < k + 1 for each edge e of G. For each k ≥ 3, we construct k-critical (multi-) graphs with certain properties to obtain counterexamples to some well-known conjectures.
## Abstract All planar connected graphs regular of degree four can be generated from the graph of the octahedron, using four operations.
## Abstract Several operations on 4‐regular graphs and pseudographs are analyzed and equations are obtained relating the numbers of these graphs on given numbers of labeled points. These equations are used recursively to find the numbers of 4‐regular graphs on up to 13 labeled points.