Hostname: page-component-586b7cd67f-r5fsc Total loading time: 0 Render date: 2024-11-28T17:27:09.307Z Has data issue: false hasContentIssue false

Linkedness and Ordered Cycles in Digraphs

Published online by Cambridge University Press:  01 May 2008

DANIELA KÜHN
Affiliation:
School of Mathematics, University of Birmingham, Edgbaston, Birmingham, B15 2TT, UK (e-mail: [email protected], [email protected])
DERYK OSTHUS
Affiliation:
School of Mathematics, University of Birmingham, Edgbaston, Birmingham, B15 2TT, UK (e-mail: [email protected], [email protected])

Abstract

Given a digraph D, let δ0(D) := min{δ+(D), δ(D)} be the minimum semi-degree of D. We show that every sufficiently large digraph D with δ0(D)≥n/2 + l −1 is l-linked. The bound on the minimum semi-degree is best possible and confirms a conjecture of Manoussakis [17]. We also determine the smallest minimum semi-degree which ensures that a sufficiently large digraph D is k-ordered, i.e., that for every sequence s1, . . ., sk of distinct vertices of D there is a directed cycle which encounters s1, . . ., sk in this order. This result will be used in [16].

Type
Paper
Copyright
Copyright © Cambridge University Press 2007

Access options

Get access to the full version of this content by using one of the access options below. (Log in options will check for institutional or personal access. Content may require purchase if you do not have access.)

References

[1]Bang-Jensen, J. and Gutin, G. (2000) Digraphs: Theory, Algorithms and Applications. Springer.Google Scholar
[2]Bollobás, B. and Thomason, A. (1996) Highly linked graphs. Combinatorica 16 313320.Google Scholar
[3]Chen, G., Faudree, R. J.Gould, R. J.Jacobson, M. S., Lesniak, L. and Pfender, F. (2004) Linear forests and ordered cycles. Discussiones Mathematicae: Graph Theory 24 359372.CrossRefGoogle Scholar
[4]Egawa, Y., Faudree, R., Győri, E., Ishigami, Y., Schelp, R. and Wang, H. (2000) Vertex-disjoint cycles containing specified edges. Graphs Combin. 16 8192.CrossRefGoogle Scholar
[5]Ferrara, M., Gould, R., Tansey, G. and Whalen, T. (2006) On H-linked graphs. Graphs Combin. 22 217224.CrossRefGoogle Scholar
[6]Fortune, S., Hopcroft, J. E. and Wyllie, J. (1980) The directed subgraph homeomorphism problem. Theoret. Comput. Sci. 10 111121.Google Scholar
[7]Ghouila-Houri, A. (1960) Une condition suffisante d'existence d'un circuit Hamiltonien. CR Acad. Sci. Paris 251 495497.Google Scholar
[8]Gould, R., Kostochka, A. V. and Yu, G. (2006) On minimum degree implying that a graph is H-linked. SIAM J. Discrete Math. 20 829840.Google Scholar
[9]Gutin, G. and Yeo, A. (2007) Some parameterized problems on digraphs. Preprint.CrossRefGoogle Scholar
[10]Heydemann, M. C. and Sotteau, D. (1985) About some cyclic properties in digraphs. J. Combin. Theory Ser. B 38 261278.CrossRefGoogle Scholar
[11]Jung, H. A. (1970) Eine Verallgemeinerung des k-fachen Zusammenhangs für Graphen. Math. Annalen 187 95103.Google Scholar
[12]Kawarabayashi, K., Kostochka, A. and Yu, G. (2006) On sufficient degree conditions for a graph to be k-linked. Combin. Probab. Comput. 15 685694.Google Scholar
[13]Kierstead, H., Sarközy, G. and Selkow, S. (1999) On k-ordered Hamiltonian graphs. J. Graph Theory 32 1725.Google Scholar
[14]Kostochka, A. and Yu, G. (2005) An extremal problem for H-linked graphs. J. Graph Theory 50 321339.CrossRefGoogle Scholar
[15]Kostochka, A. and Yu, G. Minimum degree conditions for H-linked graphs. Discrete Applied Math., to appear.Google Scholar
[16]Kühn, D., Osthus, D. and Young, A.k-ordered Hamilton cycles in digraphs. Submitted.Google Scholar
[17]Manoussakis, Y. (1990) k-linked and k-cyclic digraphs. J. Combin. Theory Ser. B 48 216226.Google Scholar
[18]Thomas, R. and Wollan, P. (2005) An improved extremal function for graph linkages. Europ. J. Combin. 26 309324.Google Scholar
[19]Thomassen, C. (1991) Note on highly connected non-2-linked digraphs. Combinatorica 11 393395.CrossRefGoogle Scholar