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.
Intersections of longest cycles in grid graphs
β Scribed by Menke, B.; Zamfirescu, T.; Zamfirescu, C.
- Publisher
- John Wiley and Sons
- Year
- 1997
- Tongue
- English
- Weight
- 292 KB
- Volume
- 25
- Category
- Article
- ISSN
- 0364-9024
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β¦ Synopsis
It is well-known that the largest cycles of a graph may have empty intersection. This is the case, for example, for any hypohamiltonian graph. In the literature, several important classes of graphs have been shown to contain examples with the above property. This paper investigates a (nontrivial) class of graphs which, on the contrary, admits no such example.
π SIMILAR VOLUMES
Given a BIBD S = (V, B), its 1-block-intersection graph GS has as vertices the elements of B; two vertices B1, B2 β B are adjacent in GS if |B1 β© B2| = 1. If S is a triple system of arbitrary index Ξ», it is shown that GS is hamiltonian.
Let G be a planar graph on n vertices, let c(G) denote the length of a longest cycle of G, and let w(G) denote the number of components of G. By a well-known theorem of Tutte, c(G) = n (i.e., G is hamiltonian) if G is 4-connected. Recently, Jackson and Wormald showed that c(G) 2 ona for some positiv
It was conjectured in [Wang, to appear in The Australasian Journal of Combinatorics] that, for each integer k β₯ 2, there exists . This conjecture is also verified for k = 2, 3 in [Wang, to appear; Wang, manuscript]. In this article, we prove this conjecture to be true if n β₯ 3k, i.e., M (k) β€ 3k. W
Let G n,m,k denote the space of simple graphs with n vertices, m edges, and minimum degree at least k, each graph G being equiprobable. Let G have property A k , if G contains (k -1)/2 edge disjoint Hamilton cycles, and, if k is even, a further edge disjoint matching of size n/2 . We prove that, for