Suppose G is a graph on n vertices with minimum degree r. Using standard random methods it is shown that there exists a two-coloring of the vertices of G with colors, +1 and &1, such that all closed neighborhoods contain more 1's than &1's, and all together the number of 1's does not exceed the numb
Maximum acyclic and fragmented sets in regular graphs
β Scribed by Penny Haxell; Oleg Pikhurko; Andrew Thomason
- Publisher
- John Wiley and Sons
- Year
- 2007
- Tongue
- English
- Weight
- 126 KB
- Volume
- 57
- Category
- Article
- ISSN
- 0364-9024
No coin nor oath required. For personal study only.
β¦ Synopsis
Abstract
We show that a typical dβregular graph G of order n does not contain an induced forest with around ${2 {\rm In} d \over d}$ vertices, when nββ«βdββ«β1, this bound being best possible because of a result of Frieze and Εuczak [6]. We then deduce an affirmative answer to an open question of Edwards and Farr (see [4]) about fragmentability, which concerns large subgraphs with components of bounded size. An alternative, direct answer to the question is also given. Β© 2007 Wiley Periodicals, Inc. J Graph Theory 57: 149β156, 2008
π SIMILAR VOLUMES
In 1975, John Sheehan conjectured that every Hamiltonian 4-regular graph has a second Hamiltonian cycle. Combined with earlier results this would imply that every Hamiltonian r-regular graph (r 3) has a second Hamiltonian cycle. We shall verify this for r 300.
## Abstract Let __m__(__G__) denote the number of maximal independent sets of vertices in a graph __G__ and let __c__(__n__,__r__) be the maximum value of __m__(__G__) over all connected graphs with __n__ vertices and at most __r__ cycles. A theorem of Griggs, Grinstead, and Guichard gives a formul
## Abstract An __acyclic__ edge coloring of a graph is a proper edge coloring such that there are no bichromatic cycles. The __acyclic chromatic index__ of a graph is the minimum number __k__ such that there is an acyclic edge coloring using __k__ colors and is denoted by __a__β²(__G__). It was conj
## Abstract A wellβknown formula of Tutte and Berge expresses the size of a maximum matching in a graph __G__ in terms of what is usually called the deficiency of __G__. A subset __X__ of __V__(__G__) for which this deficiency is attained is called a Tutte set of __G__. While much is known about ma