## Abstract We show that every 1βtough graph __G__ on __n__ β₯ 3 vertices with Ο~3~β§ __n__ has a cycle of length at least min{__n, n__ + (Ο~3~/3 ) β Ξ± + 1}, where Ο~3~ denotes the minimum value of the degree sum of any 3 pairwise nonadjacent vertices and Ξ± the cardinality of a miximum independent se
Circumferences in 1-tough graphs
β Scribed by Hao Li
- Publisher
- Elsevier Science
- Year
- 1995
- Tongue
- English
- Weight
- 270 KB
- Volume
- 146
- Category
- Article
- ISSN
- 0012-365X
No coin nor oath required. For personal study only.
β¦ Synopsis
Bauer, Morgana, Schmeichel and Veldman have conjectured that the circumference c(G) of any 1-tough graph G of order n >t 3 with minimum degree 6 >/n/3 is at least min{n,(3n+ 1)/4+6/2} ~>(lln+ 3)/12. They proved that under these conditions, c(G)>~min{n,n/2+6}>15n/6. Then Bauer, Schmeichei and Veldman improved this result by getting c(G)>lmin{n,n/2+6+ 1} >/5n/6+ 1. We show in this paper that c(G) >! min {n, (2n + 1 + 26)/3, (3n + 26 -2)/4} >/min {(8n + 3)/9, (1 In -6)/12}.
π SIMILAR VOLUMES
In this article, we establish bounds for the length of a longest cycle C in a 2-connected graph G in terms of the minimum degree Ξ΄ and the toughness t. It is shown that C is a Hamiltonian cycle or |C| β₯ (t + 1)Ξ΄ + t.
Tough nonhamiltonian n-vertex graphs with n 2 3 are known to exist only for n 3 7. The maximum size among them is shown to be 6 + (n -3)(n -4)/2. All corresponding maximum graphs are K,\*(3K,\*+ K,\_,) for n 5 7 (unique if n #9) and, additionally, K,\*Kp(3K,\*+ KS) if n = 9, where + stands for the
## Abstract Let __G__ be a graph and __T__ a set of vertices. A __Tβpath__ in __G__ is a path that begins and ends in __T__, and none of its internal vertices are contained in __T__. We define a __Tβpath covering__ to be a union of vertexβdisjoint __T__βpaths spanning all of __T__. Concentrating on