Degrees and choice numbers
β Scribed by Noga Alon
- Publisher
- John Wiley and Sons
- Year
- 2000
- Tongue
- English
- Weight
- 74 KB
- Volume
- 16
- Category
- Article
- ISSN
- 1042-9832
No coin nor oath required. For personal study only.
β¦ Synopsis
The choice number ch G of a graph G = V E is the minimum number k such that for every assignment of a list S v of at least k colors to each vertex v β V , there is a proper vertex coloring of G assigning to each vertex v a color from its list S v . We prove that if the minimum degree of G is d, then its choice number is at least 1 2 -o 1 log 2 d, where the o 1 -term tends to zero as d tends to infinity. This is tight up to a constant factor of 2 + o 1 , improves an estimate established by the author, and settles a problem raised by him and Krivelevich.
π SIMILAR VOLUMES
It is proved that for every k a4 there is a A(k) such that for eve:y g there is a graph G with maximal degree at most A(k), chromatic number at least k and girth at least g. In fact, for a fixed k, the restriction of the maximal degree to A(k) does not seem to slow down the ptiih of the maximal girt
## Abstract We consider a problem related to Hadwiger's Conjecture. Let __D__=(__d__~1~, __d__~2~, β¦, __d__~__n__~) be a graphic sequence with 0β©½__d__~1~β©½__d__~2~β©½Β·Β·Β·β©½__d__~__n__~β©½__n__β1. Any simple graph __G__ with __D__ its degree sequence is called a realization of __D__. Let __R__[__D__] denot
polynomial time enumeration method for the three-choice polygon model in two dimensions is given together with numerical analysis of the enumerated series and an argument supporting the asymptotic behaviour of the number of imperfect staircase polygons.