## Abstract A graph is uniquely hamiltonian if it contains exactly one hamiltonian cycle. In this note we prove that there are no __r__βregular uniquely hamiltonian graphs when __r__β>β22. This improves upon earlier results of Thomassen. Β© 2006 Wiley Periodicals, Inc. J Graph Theory 54: 233β244, 20
Essential independent sets and Hamiltonian cycles
β Scribed by Chen, Guantao; Egawa, Yoshimi; Liu, Xin; Saito, Akira
- Publisher
- John Wiley and Sons
- Year
- 1996
- Tongue
- English
- Weight
- 355 KB
- Volume
- 21
- Category
- Article
- ISSN
- 0364-9024
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β¦ Synopsis
An independent set S of a graph G is said to be essential if S has a pair of vertices distance t w o apart in G. We prove that if every essential independent set S of order k 2 2 in a k-connected graph of order p satisfies max{deg u : u E S} I p, then G is hamiltonian. This generalizes the result of Fan (J. Combinatorial Theory B 37 (19841,(221)(222)(223)(224)(225)(226)(227). If w e consider the essential independent sets of order k + 1 instead of k in the assumption of the above statement, w e can no longer assure the existence a hamiltonian cycle. However, we can still give a lower bound to the length of a longest cycle.
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 We find the maximum number of maximal independent sets in two families of graphs. The first family consists of all graphs with __n__ vertices and at most __r__ cycles. The second family is all graphs of the first family which are connected and satisfy __n__ββ₯β3__r__. Β© 2006 Wiley Period
## 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
Given two integers n and k, n β₯ k > 1, a k-hypertournament T on n vertices is a pair (V, A), where V is a set of vertices, |V | = n and A is a set of k-tuples of vertices, called arcs, so that for any k-subset S of V, A contains exactly one of the k! k-tuples whose entries belong to S. A 2-hypertour