A graph is (rn, k)-colorable if its vertices can be colored with rn colors in such a way that each vertex is adjacent to at most k vertices of the same color as itself. In a recent paper Cowen. Cowen, and Woodall proved that, for each compact surface S, there exists an integer k = k(S) such that eve
The number of defective colorings of graphs on surfaces
โ Scribed by Tom Rackham
- Publisher
- John Wiley and Sons
- Year
- 2010
- Tongue
- English
- Weight
- 99 KB
- Volume
- 68
- Category
- Article
- ISSN
- 0364-9024
No coin nor oath required. For personal study only.
โฆ Synopsis
A (k, 1)-coloring of a graph is a vertex-coloring with k colors such that each vertex is permitted at most 1 neighbor of the same color. We show that every planar graph has at least c n distinct (4, 1)-colorings, where c is constant and โ 1.466 satisfies 3 = 2 +1. On the other hand for any >0, we give examples of planar graphs with fewer than c(+ ) n distinct (4, 1)-colorings, where c is constant and = (1+ โ 5) / 2. Let (S) denote the chromatic number of a surface S. For every surface S except the sphere, we show that there exists a constant c = c (S)>0 such that every graph embeddable in S has at least c 2 n distinct ( (S), 1)-colorings. แญง
๐ SIMILAR VOLUMES
In this paper we present a short algebraic proof for a generalization of a formula of R. Penrose, Some applications of negative dimensional tensors, in: Combinatorial Mathematics and its Applications Welsh (ed.), Academic Press, 1971, pp. 221-244 on the number of 3-edge colorings of a plane cubic gr
## Abstract Let ${\cal F}\_{{2}{k},{k}^{2}}$ consist of all simple graphs on 2__k__ vertices and ${k}^{2}$ edges. For a simple graph __G__ and a positive integer $\lambda$, let ${P}\_{G}(\lambda)$ denote the number of proper vertex colorings of __G__ in at most $\lambda$ colors, and let $f(2k, k^{2
AND Bruce Reed Department of Combinatorics and Optimisation, University of Waterloo, Waterloo, Ontario, Canada
## Abstract Given a __list of boxes L__ for a graph __G__ (each vertex is assigned a finite set of colors that we call a box), we denote by __f__(__G, L__) the number of Lโ__colorings__ of __G__ (each vertex must be colored wiht a color of its box). In the case where all the boxes are identical and