Sharp sufficient conditions for Hamiltonian cycles in tough graphs
Z. Skupień (1989)
Banach Center Publications
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Z. Skupień (1989)
Banach Center Publications
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Magdalena Bojarska (2010)
Discussiones Mathematicae Graph Theory
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We show that every 2-connected (2)-Halin graph is Hamiltonian.
Igor Fabrici, Erhard Hexel, Stanislav Jendrol’ (2013)
Discussiones Mathematicae Graph Theory
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A nonempty vertex set X ⊆ V (G) of a hamiltonian graph G is called an H-force set of G if every X-cycle of G (i.e. a cycle of G containing all vertices of X) is hamiltonian. The H-force number h(G) of a graph G is defined to be the smallest cardinality of an H-force set of G. In the paper the study of this parameter is introduced and its value or a lower bound for outerplanar graphs, planar graphs, k-connected graphs and prisms over graphs is determined.
Hopkins, Brian (2004)
International Journal of Mathematics and Mathematical Sciences
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Jens-P. Bode, Anika Fricke, Arnfried Kemnitz (2015)
Discussiones Mathematicae Graph Theory
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In 1980 Bondy [2] proved that a (k+s)-connected graph of order n ≥ 3 is traceable (s = −1) or Hamiltonian (s = 0) or Hamiltonian-connected (s = 1) if the degree sum of every set of k+1 pairwise nonadjacent vertices is at least ((k+1)(n+s−1)+1)/2. It is shown in [1] that one can allow exceptional (k+ 1)-sets violating this condition and still implying the considered Hamiltonian property. In this note we generalize this result for s = −1 and s = 0 and graphs that fulfill a certain connectivity...
McKee, Terry A. (2008)
The Electronic Journal of Combinatorics [electronic only]
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Kewen Zhao, Ronald J. Gould (2010)
Colloquium Mathematicae
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An independent set S of a graph G is said to be essential if S has a pair of vertices that are distance two apart in G. In 1994, Song and Zhang proved that if for each independent set S of cardinality k+1, one of the following condition holds: (i) there exist u ≠ v ∈ S such that d(u) + d(v) ≥ n or |N(u) ∩ N(v)| ≥ α (G); (ii) for any distinct u and v in S, |N(u) ∪ N(v)| ≥ n - max{d(x): x ∈ S}, then G is Hamiltonian. We prove that if for each...
N. Chakroun, M. Manoussakis, Y. Manoussakis (1989)
Banach Center Publications
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Zhao, Kewen (2011)
Serdica Mathematical Journal
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2010 Mathematics Subject Classification: 05C38, 05C45. In 1952, Dirac introduced the degree type condition and proved that if G is a connected graph of order n і 3 such that its minimum degree satisfies d(G) і n/2, then G is Hamiltonian. In this paper we investigate a further condition and prove that if G is a connected graph of order n і 3 such that d(G) і (n-2)/2, then G is Hamiltonian or G belongs to four classes of well-structured exceptional graphs.
Guantao Chen, Ronald J. Gould, Ken-ichi Kawarabayashi, Katsuhiro Ota, Akira Saito, Ingo Schiermeyer (2007)
Discussiones Mathematicae Graph Theory
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Let G be a 2-connected graph of order n satisfying α(G) = a ≤ κ(G), where α(G) and κ(G) are the independence number and the connectivity of G, respectively, and let r(m,n) denote the Ramsey number. The well-known Chvátal-Erdös Theorem states that G has a hamiltonian cycle. In this paper, we extend this theorem, and prove that G has a 2-factor with a specified number of components if n is sufficiently large. More precisely, we prove that (1) if n ≥ k·r(a+4, a+1), then G has a 2-factor...
Ralph Faudree, Odile Favaron, Evelyne Flandrin, Hao Li (1996)
Discussiones Mathematicae Graph Theory
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We first show that if a graph G of order n contains a hamiltonian path connecting two nonadjacent vertices u and v such that d(u)+d(v) ≥ n, then G is pancyclic. By using this result, we prove that if G is hamiltonian with order n ≥ 20 and if G has two nonadjacent vertices u and v such that d(u)+d(v) ≥ n+z, where z = 0 when n is odd and z = 1 otherwise, then G contains a cycle of length m for each 3 ≤ m ≤ max (dC(u,v)+1, [(n+19)/13]), being the distance of u and v on a hamiltonian cycle...
Ronald J. Gould (1981)
Colloquium Mathematicae
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Fleischner, H., Horák, P., Širáň, J. (1993)
Acta Mathematica Universitatis Comenianae. New Series
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Tudor Zamfirescu (1971)
Rendiconti del Seminario Matematico della Università di Padova
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Peter Horák, Leoš Továrek (1979)
Mathematica Slovaca
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